 United States Court of Appeals
          FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued December 1, 2015             Decided October 20, 2016

                         No. 11-1324

          ALI HAMZA AHMAD SULIMAN AL BAHLUL,
                      PETITIONER

                               v.

                UNITED STATES OF AMERICA,
                       RESPONDENT


              On Petition for Rehearing En Banc


     Michel Paradis, Counsel, Office of the Chief Defense
Counsel, argued the cause for petitioner. With him on the
briefs were Mary R. McCormick and Todd E. Pierce, Counsel.

     David Weissbrodt and William J. Aceves were on the
brief for amici curiae International Law Scholars in support
of petitioner.

    J. Douglas Richards was on the brief for amicus curiae
National Institute of Military Justice in support of petitioner.

    Robert Barton was on the brief for amicus curiae
Professor David Glazier in support of petitioner.

   Ian Heath Gershengorn, Principal Deputy Solicitor
General, U.S. Department of Justice, argued the cause for
                                     2
respondent. On the brief were Steven M. Dunne, Chief,
Appellate Unit, and John F. De Pue and Joseph Palmer,
Attorneys.

    James A. Schoettler Jr. was on the brief for amici curiae
Former Government Officials, Former Military Lawyers, and
Scholars of National Security Law in support of respondent.

     Richard A. Samp was on the brief for amici curiae John
D. Altenburg, Maj. Gen., U.S. Army (Ret)., et al. in support
of respondent.

    Before: GARLAND, Chief Judge, and HENDERSON,
ROGERS, TATEL, BROWN, GRIFFITH, KAVANAUGH,
SRINIVASAN, MILLETT, PILLARD, and WILKINS, Circuit
Judges.

       Opinion for the Court filed PER CURIAM.

       Concurring opinion filed by Circuit Judge HENDERSON.

    Concurring opinion filed by Circuit Judge KAVANAUGH,
with whom Circuit Judges BROWN and GRIFFITH join.

       Concurring opinion filed by Circuit Judge MILLETT.

       Concurring opinion filed by Circuit Judge WILKINS.

   Joint Dissenting opinion filed by Circuit Judges ROGERS,
TATEL, and PILLARD.



  Chief Judge Garland was a member of the en banc court at the
time the case was argued but did not participate in this opinion.

     Circuit Judge Srinivasan did not participate in this matter.
                               3


     PER CURIAM: Bahlul is a member of al Qaeda who
assisted Osama bin Laden in planning the September 11,
2001, attacks on the United States. Bahlul was convicted by a
U.S. military commission of the offense of conspiracy to
commit war crimes, among other offenses. The U.S. Court of
Military Commission Review affirmed Bahlul’s conviction.

     In a prior en banc decision, we recounted the facts and
considered Bahlul’s Ex Post Facto Clause objection to the
conspiracy conviction. Applying plain error review, we
concluded that the Ex Post Facto Clause did not preclude the
conspiracy charge against Bahlul. See Al Bahlul v. United
States, 767 F.3d 1 (D.C. Cir. 2014) (en banc).

     In this en banc case, Bahlul argues that Articles I and III
of the Constitution bar Congress from making conspiracy an
offense triable by military commission, because conspiracy is
not an offense under the international law of war.

    We affirm the judgment of the U.S. Court of Military
Commission Review upholding Bahlul’s conspiracy
conviction. Six judges – Judges Henderson, Brown, Griffith,
Kavanaugh, Millett, and Wilkins – have voted to affirm.
Three judges – Judges Rogers, Tatel, and Pillard – dissent.

    Of the six-judge majority, four judges (Judges
Henderson, Brown, Griffith, and Kavanaugh) would affirm
because they conclude that, consistent with Articles I and III
of the Constitution, Congress may make conspiracy to
commit war crimes an offense triable by military commission.
They would uphold Bahlul’s conspiracy conviction on that
basis.
                              4
    Judge Millett would apply plain error review and affirm
Bahlul’s conviction under that standard of review. She would
not reach the question of whether Congress may make
inchoate conspiracy an offense triable by military
commission.

     Judge Wilkins would affirm because he concludes that
the particular features of Bahlul’s conviction demonstrate that
Bahlul was not convicted of an inchoate conspiracy offense.
He further concludes that Bahlul’s conviction complies with
the Constitution because the particular features of Bahlul’s
conviction have sufficient roots in international law. He
therefore would not reach the question of whether Congress
may make inchoate conspiracy an offense triable by military
commission.

     Judges Rogers, Tatel, and Pillard have filed a Joint
Dissent. They conclude that Article III of the Constitution
bars Congress from making inchoate conspiracy an offense
triable by a law-of-war military commission.

     Bahlul has also raised First Amendment and Equal
Protection challenges to his conviction. The Court rejects
those challenges. See Kavanaugh Concurring Op. at 24 n.12;
Millett Concurring Op. at 2, 44-45; Wilkins Concurring Op. at
14. The Joint Dissent neither reaches those claims nor adopts
the above characterization of the facts.

                            ***

    We affirm the judgment of the U.S. Court of Military
Commission Review upholding Bahlul’s conspiracy
conviction.
                                             So ordered.
     KAREN LECRAFT HENDERSON, Circuit Judge, concurring:
I join the Court’s judgment affirming Bahlul’s conspiracy
conviction. I do so for the reasons stated in my dissent in Al
Bahlul v. United States, 792 F.3d 1, 27-72 (D.C. Cir. 2015)
(since vacated). I incorporate by reference thereto that
previously published opinion as my concurrence here.
     ‎KAVANAUGH, Circuit Judge, with whom Circuit Judges
BROWN and GRIFFITH join, concurring: Pursuant to
congressional authorization, Presidents throughout U.S.
history have employed military commissions to try enemy
war criminals for conspiracy to commit war crimes. That
history includes the two most significant U.S. military
commission trials: the 1865 military commission trial of the
Confederate conspirators who plotted to kill President Lincoln
and the 1942 military commission trial of the Nazi
conspirators who secretly entered the United States during
World War II and planned to attack U.S. infrastructure and
military facilities.

     In‎the‎wake‎of‎al‎Qaeda’s‎attacks‎on‎the‎United‎States‎on‎
September 11, 2001, Congress has twice passed laws (signed
by President Bush in 2006 and President Obama in 2009)
expressly reaffirming that military commissions may try
unlawful enemy combatants for conspiracy to commit war
crimes. Pursuant to those express congressional
authorizations, President Bush and later President Obama
have employed military commissions to try alleged al Qaeda
war criminals for the offense of conspiracy to commit war
crimes. Indeed, Khalid Sheikh Mohammed, one of the
alleged masterminds of the September 11th attacks, faces a
conspiracy charge in his pending military commission trial.
Several other al Qaeda members likewise have been charged
with conspiracy before U.S. military commissions.

     Bahlul is an al Qaeda member who worked closely with
Osama‎ bin‎ Laden‎ in‎ plotting‎ al‎ Qaeda’s‎ September‎ 11th‎
attacks on the United States. In December 2001, Bahlul was
captured in Pakistan. In 2008, he was tried and convicted
before a U.S. military commission of conspiracy to commit
war crimes.

    Citing Article I and Article III of the Constitution, Bahlul
argues that Congress may establish military commissions only
                               2
for offenses under the international law of war. Bahlul
further argues (and the Government concedes) that conspiracy
is not an offense under the international law of war.
Therefore, Bahlul contends that he may not be tried for
conspiracy before a U.S. military commission.

     On‎its‎face,‎Bahlul’s‎argument‎is‎extraordinary.‎It‎would‎
incorporate international law into the U.S. Constitution as a
judicially enforceable constraint on Congress and the
President. As a matter of U.S. constitutional law, the wartime
decisions of Congress and the President to try unlawful
enemy combatants before military commissions would be
subject to the dictates of foreign nations and the international
community, as embodied in international law.

      The Government responds that, under the Constitution,
Congress may establish military commissions to try, at a
minimum, (i) international law of war offenses and
(ii) offenses that are not international law of war offenses but
have historically been tried by U.S military commissions. As
the Government points out, conspiracy has historically been
tried by U.S. military commissions.

     This case therefore raises one central legal question:
Under the U.S. Constitution, may Congress establish military
commissions to try unlawful enemy combatants for the
offense of conspiracy to commit war crimes, even if
conspiracy is not an offense under the international law of
war? The answer is yes. We know that from the text and
original understanding of the Constitution; the structure of the
Constitution;    landmark Supreme Court              precedent;
longstanding congressional practice, as reflected in venerable
                                 3
and contemporary federal statutes; and deeply rooted
Executive Branch practice, from the 1800s to the present.1

    1
        The Government argues that Bahlul forfeited this claim.
Even if that were true, the Court should review the claim de novo,
not simply for plain error. In rare and extraordinarily important
cases, the Court has discretion to hear even a forfeited claim de
novo. See Plaut v. Spendthrift Farm, Inc., 514 U.S. 211, 232
(1995). The question of whether conspiracy may constitutionally
be tried by military commission is extraordinarily important and
deserves‎ a‎ “definitive answer.”‎ ‎ Al Bahlul v. United States, 767
F.3d 1, 62 (D.C. Cir. 2014) (en banc) (separate opinion of Brown,
J.). The question implicates an important part of the U.S.
Government’s‎war‎strategy.‎‎And‎other cases in the pipeline require
a clear answer to the question. This case unfortunately has been
pending in this Court for more than five years. It is long past time
for us to resolve the issue squarely and definitively.
     Judge Kavanaugh adds that he would apply de novo review for
that reason, as well as for any of five other independent reasons.
First, before the military judge, Bahlul objected to the military
commission’s‎authority‎to‎try‎him‎for‎the‎charged‎offenses. Bahlul
did not forfeit this claim. Second, even if Bahlul had not objected,
the question of whether the Constitution requires Article III courts
to try conspiracy offenses is a structural question of subject matter
jurisdiction, and cannot be forfeited or waived. See Ex Parte
Quirin, 317 U.S. 1, 25 (1942) (describing the question as one of
“jurisdiction”).‎‎Third, in any event, Rules 905 and 907 of the Rules
for Military Commissions require de novo judicial review of the
question whether a charged offense may be tried by military
commission. Fourth, even if all of those points are incorrect, the
Government has repeatedly forfeited any forfeiture argument
during the course of this litigation. For example, before the U.S.
Court of Military Commission Review, the Government expressly
acknowledged‎that‎Bahlul’s‎argument‎was‎not forfeited or waived.
See Bahlul Appendix at 161 n.5 (quoting‎ Government’s‎
submission: “The‎ Government‎ does‎ not‎ argue”‎ that‎ Bahlul’s‎
argument‎“questioning‎jurisdiction”‎is “waived.”).‎‎Only‎at‎the‎11th‎
hour has the Government belatedly claimed that Bahlul forfeited his
                                  4
                                  I

     We first address the Article I issue. Bahlul acknowledges
that Congress possesses authority under Article I to establish
military commissions to try war crimes. But he contends that
military commissions may try only international law of war
offenses.    Bahlul further argues (and the Government
concedes) that conspiracy is not an international law of war
offense. Therefore, Bahlul says he may not be tried by
military commission for conspiracy.

     Contrary‎ to‎ Bahlul’s‎ argument, Article I of the
Constitution does not impose international law as a limit on
Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
commission.2 That is apparent from five sources of law: the
text and original understanding of Article I, the overall
structure of the Constitution, landmark Supreme Court
precedent, longstanding federal statutes, and deeply rooted
U.S. military commission practice.



constitutional argument. Fifth, even if Bahlul forfeited his
argument and plain error review applied here, the Court when
applying plain error often holds that there was no error, rather than
merely holding that any possible error was not plain. We should do
the same here.
      2
        To be clear, Congress may and sometimes does incorporate
international law principles into statutes. In doing so, Congress may
on‎occasion‎enact‎statutes‎that‎simply‎refer‎to‎“international‎law”‎in‎
general terms. See, e.g., 22 U.S.C. §§ 5604-5605 (empowering the
President to impose sanctions on foreign countries that use
chemical‎or‎biological‎weapons‎“in‎violation‎of‎international‎law”).
Likewise, the President and Senate may enter into self-executing
treaties with foreign nations. See Medellin v. Texas, 552 U.S. 491,
505 n.2 (2008). Those statutes and self-executing treaties are U.S.
law, not international law.
                                  5
   First, the text and original understanding of Article I
demonstrate that international law does not impose a limit on
Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
commission.

      The‎ premise‎ of‎ Bahlul’s‎ Article‎ I‎ argument‎ is‎ that‎
Congress’s‎ sole source of constitutional authority to make
offenses triable by military commission is the Define and
Punish Clause of Article I. That Clause grants Congress
authority‎to‎“define‎and‎punish . . . Offences against the Law
of‎Nations.”‎‎U.S. CONST. art. I, § 8, cl. 10. Bahlul argues that
the‎ “law‎ of‎ nations”‎ is‎ a‎ synonym‎ for‎ international‎ law,‎ and‎
further contends that conspiracy is not an offense under the
international law of war. Therefore, according to Bahlul,
Congress lacks power under Article I, Section 8 to make
conspiracy an offense triable by military commission.

    We need not decide the scope of the Define and Punish
Clause in this case.3 That‎is‎because‎the‎premise‎of‎Bahlul’s‎
Article I argument is flawed. Regardless of the scope of the
Define and Punish Clause, an issue we do not decide,
Congress’s‎ Article‎ I‎ authority‎ to‎ establish‎ military‎
commissions – including its authority to determine which
crimes may be tried by military commission – does not derive
exclusively from that Clause.


     3
        Judge Henderson and Judge Brown have previously
concluded that the Define and Punish Clause grants Congress
authority to make conspiracy an offense triable by military
commission. See Al Bahlul v. United States, 792 F.3d 1, 44-55
(D.C. Cir. 2015) (Henderson, J., dissenting); Al Bahlul v. United
States, 767 F.3d 1, 53-62 (D.C. Cir. 2014) (en banc) (separate
opinion of Brown, J.).
                                 6
     Rather, the war powers clauses in Article I, Section 8 –
including the Declare War Clause and the Captures Clause,
together with the Necessary and Proper Clause – supply
Congress with ample authority to establish military
commissions and make offenses triable by military
commission. And the Declare War Clause and the other war
powers clauses in Article I do not refer to international law or
otherwise impose international law as a constraint on
Congress’s‎ authority‎ to‎ make‎ offenses‎ triable‎ by‎ military‎
commission. Cf. Al Bahlul v. United States, 792 F.3d 1, 55-
56 (D.C. Cir. 2015) (Henderson, J., dissenting).

     As the Supreme Court has long recognized, a
congressional authorization of war pursuant to the Declare
War‎ Clause‎ is‎ understood‎ “by‎ universal‎ agreement‎ and‎
practice”‎to‎encompass‎all‎of‎the‎traditional‎incidents‎of‎war‎–
including the power to kill, capture, and detain enemy
combatants, and most relevant here, the power to try unlawful
enemy combatants by military commission for war crimes.
Hamdi v. Rumsfeld, 542 U.S. 507, 518 (2004) (binding
opinion‎of‎O’Connor,‎J.);‎see also Hamdan v. Rumsfeld, 548
U.S. 557, 593-94 (2006); In re Yamashita, 327 U.S. 1, 11-12
(1946).4 As Colonel William Winthrop, described by the
Supreme‎Court‎as‎the‎“Blackstone‎of‎Military‎ Law,”‎ Reid v.
Covert, 354 U.S. 1, 19 n.38 (1957) (plurality opinion),
summarized‎ it:‎ “[I]n general, it is those provisions of the
Constitution‎ which‎ empower‎ Congress‎ to‎ ‘declare‎ war’‎ and‎
‘raise‎armies,’‎and‎which,‎in‎authorizing‎the‎initiation‎of‎war,
authorize the employment of all necessary and proper
agencies for its due prosecution, from which this tribunal
derives its original sanction. . . . The commission is simply an

    4
      On September 18, 2001, Congress authorized the use of force
against al Qaeda and related terrorist groups. See Authorization for
Use of Military Force, Pub. L. No. 107-40, 115 Stat. 224.
                                 7
instrumentality for the more efficient execution of the war
powers vested in Congress and the power vested in the
President as Commander-in-chief‎ in‎ war.”‎ ‎ WILLIAM
WINTHROP, MILITARY LAW AND PRECEDENTS 831 (rev. 2d
ed. 1920); see also Hamdan, 548 U.S. at 592 n.21 (quoting
Winthrop’s‎ statement‎ that‎ the‎ Declare‎ War‎ Clause,‎ among‎
others, supplies Congress with authority to establish military
commissions to try war crimes). So too, Justice Story
explained‎ that‎ Congress’s‎ power‎ to‎ make‎ substantive‎ and‎
procedural‎ rules‎ for‎ military‎ commissions‎ is‎ a‎ “natural‎
incident to the preceding powers to make war, to raise armies,
and‎ to‎ provide‎ and‎ maintain‎ a‎ navy.”‎ ‎ 3‎ JOSEPH STORY,
COMMENTARIES ON THE CONSTITUTION OF THE UNITED
STATES § 1192 (1833).5

     In short, it would be textually and historically inaccurate
to deem the Define and Punish Clause, whatever its scope, as
the sole source‎ of‎ Congress’s‎ authority‎ here.‎ ‎ The‎ Declare‎
War Clause and the other war powers clauses in Article I
authorize Congress to establish military commissions and
make offenses triable by military commission. And those
clauses do not refer to international law or otherwise impose
international law as a constraint on Congress’s‎ authority‎ to‎
make offenses triable by military commission. By their
terms, therefore, those clauses do not confine U.S. military
commissions to trying only international law of war offenses.


    5
       Contrary to the suggestion advanced by Bahlul and the joint
dissent, it would be absurd to say that the war powers clauses grant
Congress authority to establish military commissions but not to
specify which offenses may be tried by military commission. There
is no support in Supreme Court precedent for slicing and cabining
Congress’s‎ war‎ powers‎ authority‎ in‎ that‎ way.‎ Moreover,‎ the‎
longstanding historical practice in the Legislative and Executive
Branches flatly contravenes that suggestion.
                                 8
     Second, the overall structure of the Constitution strongly
reinforces the conclusion that international law does not
impose‎ a‎ limit‎ on‎ Congress’s‎ authority‎ to‎ make‎ offenses‎
triable by military commission.

     The Framers of the Constitution paid careful attention to
the allocation of war powers between the national government
and the states, and within the national government. The
Framers assigned the national government – in particular,
Congress and the President – the authority to make wartime
decisions on behalf of the United States. The Framers
assigned that power to the national government in part
because the inability to wage war effectively had been one of
the key weaknesses of the Articles of Confederation, and the
Framers sought to fix that flaw.

     What matters most for present purposes is that the
Framers certainly did not purport to afford foreign nations
(acting through the international law of war or otherwise) any
constitutional authority over the wartime decisions of the
United States, such as the determination of which war crimes
may be prosecuted by U.S. military commissions. It would be
a historical‎ anomaly‎ to‎ conclude‎ that‎ “We‎ the‎ People‎ of‎ the‎
United‎States”‎gave‎foreign‎or‎international‎bodies‎the‎power‎
to constrain U.S. war-making authority in that way. Yet that
would be the necessary consequence of the argument put
forward by Bahlul and the joint dissent. They would
incorporate international law into the U.S. Constitution as a
judicially enforceable constraint on the wartime decisions of
the Congress and the President. As a matter of U.S.
constitutional law, Congress and the President would be
subject to the dictates of the international community, a
community that at any given time may be unsupportive of or
even hostile to U.S. national security interests.
                                9
      Put simply, the argument advanced by Bahlul and the
joint‎ dissent‎ does‎ not‎ comport‎ with‎ the‎ Constitution’s‎
structure. The Constitution does not give foreign nations
(acting through the international law of war or otherwise) a de
facto‎veto‎over‎Congress’s‎determination‎of‎which‎war‎crimes
may be tried by U.S. military commissions.

     Third,‎ consistent‎ with‎ the‎ Constitution’s‎ text‎ and‎
structure, landmark Supreme Court precedent likewise
supports‎the‎conclusion‎that‎Congress’s‎authority‎to‎establish‎
offenses triable by military commission is not confined by
international law.

     The‎ Supreme‎ Court’s‎ leading‎ constitutional‎ decision‎
regarding military commissions is Ex Parte Quirin. There,
the Supreme Court ruled that use of military commissions to
try war crimes was constitutionally permissible. In doing so,
the Court emphasized that U.S. military commissions have
long been authorized by Congress, and the Court noted in
particular that military commissions have long tried the
offense of spying. See Ex Parte Quirin, 317 U.S. 1, 41-42 &
n.14 (1942). But spying was not and has never been an
offense under the international law of war. See Government
Br. 45 (spying not an international law of war offense); see
also National Institute of Military Justice Amicus Br. 14-15
n.6 (same); Curtis A. Bradley & Jack L. Goldsmith,
Congressional Authorization and the War on Terrorism, 118
HARV. L. REV. 2047, 2132 (2005) (same). The Court
nonetheless relied on and approved of trying spying offenses
by military commission.6 Quirin is admittedly a difficult
    6
      The Quirin Court’s‎discussion‎of‎spying‎was‎not‎dicta.‎‎One‎
primary basis for the‎ Court’s‎ finding‎ a‎ military‎ commission‎
exception to Article III was the longstanding statute that made
spying an offense triable by military commission. See Quirin, 317
U.S. at 41-42.‎But‎even‎if‎the‎Supreme‎Court’s‎reference‎to‎spying‎
                                 10
decision‎ to‎ decipher.‎ ‎ But‎ the‎ Supreme‎ Court’s‎ reliance‎ on‎
spying, a non-international-law-of-war offense, as an offense
triable by military commission at least suggests – even if it
does not conclusively show – that Congress has authority
under Article I to make offenses triable by military
commission even if those offenses are not war crimes under
the international law of war.7

     The Court in Quirin did not say that military
commissions are constitutionally permitted only for
international law of war offenses. Nor did any later Supreme
Court case hold that military commissions are constitutionally
permitted only for international law of war offenses. One
would have expected the Court at some point to say as much
if the Court actually thought as much.



were dicta, we as a lower court generally treat Supreme Court dicta
as authoritative. See United States v. Dorcely, 454 F.3d 366, 375
(D.C.‎Cir.‎2006)‎(“[C]arefully considered language of the Supreme
Court, even if technically dictum, generally must be treated as
authoritative.”) (internal quotation marks and citations omitted);
Bangor Hydro-Electric Co. v. FERC, 78 F.3d 659, 662 (D.C. Cir.
1996)‎ (“It‎ may‎ be‎ dicta, but Supreme Court dicta tends to have
somewhat greater force – particularly when expressed so
unequivocally.”). The Quirin Court’s‎ discussion‎ of‎ spying‎ was‎
hardly the kind of stray comment that a lower court can or should
cast aside.
     7
        To be sure, the Quirin Court did not expressly state that
Congress may make non-international-law-of-war offenses triable
by military commission. Had it explicitly done so, the question
would be indisputably resolved and we would not be facing the
current litigation, after all. But in considering an objection to trial
by military commission, the Court did rely on a longstanding
statute that made spying, a non-international-law-of-war offense,
triable by military commission.
                              11
     An amicus brief nonetheless argues that the Quirin Court
thought that international law was a constitutional constraint
on Congress but that the Quirin Court believed, albeit
mistakenly, that spying was an international law of war
offense. See National Institute of Military Justice Amicus Br.
at 14 n.6. The joint dissent agrees. See Dissenting Op. at 25-
26. That argument lacks foundation. To begin with, the
Supreme Court never said anything to the effect that
Congress’s‎ constitutional authority to make offenses triable
by military commission is constrained by the international law
of war. Moreover, the idea that the Court actually thought
spying was an international law offense necessarily assumes
that the Quirin Court – with Justices such as Harlan Fiske
Stone, Felix Frankfurter, Robert Jackson, and Hugo Black –
was ignorant of the content of international law. We cannot
plausibly make such an assumption. There is no indication in
the opinion or historical record that the Quirin Court actually
believed that spying was an international law of war offense.
Nor do any later Supreme Court cases suggest as much. On
the contrary, the Quirin Court cited authorities that indicated
that spying was not an international law of war offense. See
Quirin, 317 U.S. at 30 n.7, 31 n.8, 32, 34, 37 (citing, among
other authorities, (i) the Hague Convention No. IV, art. 1
(annex), 36 Stat. 2295 and (ii) the 1940 U.S. War
Department’s‎ Rules‎ of‎ Land‎ Warfare,‎ which‎ states‎ in‎
Paragraph‎ 203‎ that‎ spying‎ “involves‎ no‎ offense‎ against
international‎law”).

     To be sure, the Quirin Court discussed international law
authorities. Those international law authorities were relevant
for, among other things, determining whether the charged
offenses could be tried by military commission under Article
15 of the Articles of War, which is present-day Article 21 of
the Uniform Code of Military Justice, or 10 U.S.C. § 821.
That statute has long used‎ the‎ broad‎ term‎ “law‎ of‎ war”‎ to‎
                                12
define the scope of offenses triable by military commission.
The Court discussed those authorities in part because an
offense’s‎ status‎ as‎ an‎ international‎ law‎ of‎ war‎ offense‎ is‎
sufficient but not necessary to make an offense triable by U.S.
military‎ commission‎ under‎ the‎ “law‎ of‎ war”‎ prong‎ of‎ 10‎
U.S.C. § 821. See Quirin, 317 U.S. at 46; Al Bahlul v. United
States, 767 F.3d 1, 65-72 (D.C. Cir. 2014) (en banc) (separate
opinion of Kavanaugh, J.); see also Hamdan, 548 U.S. at 594-
95. But the Quirin Court never stated that the international
law of war constituted a constitutional limit‎ on‎ Congress’s‎
authority to make offenses triable by military commission.

     Fourth, when we interpret the Constitution, especially the
provisions related to the separation of powers, the historical
practice of the Legislative and Executive Branches matters.
See Zivotofsky v. Kerry, 135 S. Ct. 2076, 2091, slip op. at 20
(2015)‎ (“In‎ separation-of-powers cases this Court has often
put‎ significant‎ weight‎ upon‎ historical‎ practice.”)‎ (internal‎
quotation marks omitted); NLRB v. Noel Canning, 134 S. Ct.
2550, 2560, slip op. at 7 (2014) (“[L]ongstanding practice of
the government can inform our determination of what the law
is.”)‎ (internal‎ quotation‎ marks‎ and‎ citations omitted); The
Pocket Veto Case, 279 U.S. 655, 689 (1929) (“Long‎ settled‎
and established practice is a consideration of great weight in a
proper interpretation of constitutional provisions .‎ .‎ .‎ .”);‎
McCulloch v. Maryland, 17 U.S. 316, 401 (1819) (when
considering a separation of powers question, court should
“receive‎ a‎ considerable‎ impression”‎ from‎ longstanding‎
practice).

     In this case, turning first to the Legislative Branch,
Congress’s‎ longstanding‎ practice‎ strongly‎ supports‎ the‎
conclusion that international law is not a constitutional
constraint‎ on‎ Congress’s‎ authority‎ to‎ make‎ particular crimes
triable by military commission. From the earliest days of the
                             13
Republic, Congress has gone beyond international law in
specifying the offenses that may be tried by military
commission. Beginning in 1776, the Continental Congress
codified the offense of spying – a non-international-law
offense – as a crime triable by military tribunal. See
Resolution of the Continental Congress (Aug. 21, 1776), in 5
JOURNALS OF THE CONTINENTAL CONGRESS 1774 – 1789, at
693 (Worthington Chauncey Ford ed. 1906) [hereinafter
“JOURNALS”] (authorizing‎ trial‎ by‎ military‎ court‎ of‎ “all‎
persons, not members of, nor owing allegiance to, any of the
United States of America . . . who shall be found lurking as
spies”);‎ see also WILLIAM WINTHROP, MILITARY LAW AND
PRECEDENTS 765-66 & n.88 (rev. 2d ed. 1920). Likewise, in
September 1776, Congress authorized trial by military
tribunal for another non-international-law offense: aiding the
enemy. See Articles of War (Sept. 20, 1776), in 5 JOURNALS,
at 799. In 1789, after the Constitution was ratified, the First
Congress adopted the same Articles of War that had been
promulgated by the Continental Congress, including the
offenses of spying and aiding the enemy. See Act of Sept. 29,
1789, ch. 25, §4, 1 Stat. 95, 96 (1789). Again in 1806,
Congress updated those provisions and, in doing so, was
careful to preserve the offenses of spying and aiding the
enemy as crimes triable by military tribunal. See Articles of
War of 1806, ch. 20, arts. 56, 57, § 2, 2 Stat. 359, 366, 371
(1806). Both of those prohibitions remain on the books today.
See 10 U.S.C. §§ 950t(26), 950t(27). Congress has made
those two crimes triable by military commission even though
they are not international law of war offenses.

     Congress’s‎ practice‎ of‎ going‎ beyond international law
has continued to the present. As recently as 2006 and 2009,
Congress enacted new laws making several non-international-
law offenses, such as solicitation and material support for
terrorism, triable by military commission. See Military
                                 14
Commissions Act of 2006, Pub. L. No. 109-366, 120 Stat.
2600, 2630; Military Commissions Act of 2009, Pub. L. No.
111-84, 123 Stat. 2574, 2611.

     That consistent congressional practice requires our
respect.‎As‎the‎Supreme‎Court‎has‎stated,‎the‎“uniform, long-
continued and undisputed legislative practice just disclosed
rests upon an admissible view of the Constitution which, even
if the practice found far less support in principle than we think
it does, we should not feel at liberty at this late day to
disturb.”‎ United States v. Curtiss-Wright Export Corp., 299
U.S. 304, 329 (1936).

     The joint dissent responds that Congress, over the course
of more than two centuries, actually thought itself bound by
international law but believed (mistakenly) that those offenses
– spying and aiding the enemy, for example – were in fact
international law offenses. See Dissenting Op. at 34-36. That
assertion seems to materialize out of thin air. We are aware
of no credible support for the notion that Congress has
believed itself bound by international law in this context or
has thought that those offenses were in fact international law
offenses. Moreover, the joint dissent does not deal with the
persistence of congressional practice – from the Founding to
the recent 2006 and 2009 Acts. In short, the deeply rooted
congressional‎ practice‎ directly‎ contradicts‎ the‎ joint‎ dissent’s‎
position.

     Fifth, in addition to the historical practice in Congress,
the historical practice in the Executive Branch demonstrates
that international law is not a constraint on which offenses
may be tried by military commissions. Indeed, perhaps the
most telling factor when considering this constitutional
question is the deeply rooted history of U.S. military
commission trials of the offense of conspiracy, which is not
                                15
and has never been an offense under the international law of
war. Cf. Zivotofsky, 135 S. Ct. at 2091, slip‎ op.‎ at‎ 20‎ (“In‎
separation-of-powers cases this Court has often put significant
weight‎ upon‎ historical‎ practice.”)‎ (internal‎ quotation‎ marks‎
omitted); Noel Canning, 134 S. Ct. at 2560, slip op. at 7
(“[L]ongstanding practice of the government can inform our
determination‎ of‎ what‎ the‎ law‎ is”)‎ (internal‎ quotation‎ marks‎
and citations omitted).

    The two most important military commission precedents
in U.S. history – the trials of the Lincoln conspirators and the
Nazi saboteurs – were trials for the offense of conspiracy.

     Consider the trial of the Lincoln conspirators. After
seeking the advice of the Attorney General, President Andrew
Johnson decided to try the Lincoln conspirators by military
commission rather than by criminal trial in civilian court. See
Military Commissions, 11 Op. Attorney Gen. 297, 298
(1865). The Lincoln conspirators were expressly charged with
and convicted of conspiracy – in that case, conspiracy to
violate the law of war by killing the President and
Commander in Chief of the Union Army, Abraham Lincoln.
Indeed, conspiracy was the only offense charged against them.
After an extensive multi-week trial that gripped the Nation
and after vigorous argument about the facts and the
commission’s‎ jurisdiction,‎ numerous‎ conspirators‎ were‎
convicted of conspiracy.

     The joint dissent tries to cast doubt on whether the
Lincoln conspirators were actually tried for conspiracy. There
is no doubt. Consider what a contemporary court said in
response to a habeas petition filed by three of the Lincoln
conspirators:‎ ‎ “[T]he‎ prisoners‎ are‎ guilty‎ of‎ the‎ charge‎ on‎
which they were convicted – of a conspiracy to commit the
military crime which one of their number did commit, and
                                 16
some‎of‎them‎of‎more‎or‎less‎participation.”‎‎Ex parte Mudd,
17 F. Cas. 954 (S.D. Fla. 1868).8 Indeed, in the prior en banc
decision in this case, our Court (joined by one of the judges
who joins the joint dissent today) described the Lincoln case
as‎ a‎ trial‎ for‎ conspiracy‎ and‎ stated‎ that‎ “the‎ sole‎ offense‎
alleged‎was‎conspiracy.”‎Al Bahlul v. United States, 767 F.3d
1, 25 (D.C. Cir. 2014) (en banc). Our en banc Court
explained‎that‎the‎Lincoln‎case‎was‎a‎“particularly‎significant‎
precedent”‎ and‎ a‎ “high-profile example of a conspiracy
charge‎tried‎by‎a‎military‎commission.”‎Id.; see also Al Bahlul
v. United States, 792 F.3d 1, 59-61 (D.C. Cir. 2015)
(Henderson, J., dissenting).

     Consider also the military commission trial of the eight
Nazi saboteurs who had been selected to execute Operation
Pastorius – Adolf‎ Hitler’s‎ plan‎ to‎ destroy‎ America’s‎ war‎
industries and facilities – and secretly entered the United
States during World War II. The defendants were expressly
charged with and convicted of conspiracy, as well as of other
offenses. Attorney General of the United States Francis
Biddle, who would later represent the United States as a judge
at Nuremberg, personally prosecuted the case before the
military commission. President Franklin Roosevelt reviewed
and approved all of the convictions. The defendants filed
habeas corpus petitions to block the proceedings as
unconstitutional. The Supreme Court affirmed the legality of


    8
       Although the original records for the Southern District of
Florida from that time period were initially lost, a copy of Judge
Boynton’s‎ opinion‎ for‎ the‎ court‎ is on file with the Library of
Congress. Moreover, the opinion was published in full in the New
York Times on October 1, 1868 – precisely one month after the
decision was handed down by the court. The Application in Behalf
of Dr. Mudd, Arnold and Spangler – Opinion of Judge Boynton,
N.Y. TIMES at 2 (Oct. 1, 1868).
                              17
the trial, and in doing so, did not disturb the conspiracy
charge. See Quirin, 317 U.S. at 46.

     Later in World War II, moreover, the Government
prosecuted another set of Nazi saboteurs for conspiracy and
tried them before a military commission. In that case,
Assistant Attorney General Tom Clark, who would later serve
on the Supreme Court, produced a formal memorandum –
based in large part on the precedents involving the Lincoln
conspirators and the earlier Nazi saboteurs – concluding that
conspiracy was an offense triable by military commission.
See Memorandum from Tom C. Clark, Assistant Attorney
General, to Myron C. Kramer, Judge Advocate General (Mar.
12, 1945), reprinted in Government Supplemental Appendix
104-10.‎‎In‎Assistant‎Attorney‎General‎Clark’s‎words,‎it‎was‎
“well‎ established‎ that‎ a‎ conspiracy‎ to‎ commit‎ an‎ offense‎
against the laws of war is itself an offense cognizable by a
commission‎ administering‎ military‎ justice.” Id. at 110. The
military commission subsequently convicted the defendants of
conspiracy. President Truman reviewed and affirmed the
convictions.     After one of those Nazi saboteurs later
challenged his conviction in court, the Tenth Circuit affirmed
the denial of his habeas petition, and the Supreme Court
denied certiorari. The Tenth Circuit stated the charges against
him‎ were‎ clearly‎ “within‎ the‎ jurisdiction‎ of‎ the‎ duly‎
constituted Military Commission with power to try, decide
and condemn.” Colepaugh v. Looney, 235 F.2d 429, 432 (10th
Cir. 1956), cert. denied, 352 U.S. 1014 (1957).

     Put simply, the most well-known and important U.S.
military commissions in American history tried and convicted
the defendants of conspiracy. That history matters. See
Zivotofsky, 135 S. Ct. at 2091, slip op. at 20; Noel Canning,
134 S. Ct. at 2559-60, slip op. at 6-7. And that history is
directly on point here because conspiracy is not an
                                  18
international law of war offense and because conspiracy is the
precise offense that Bahlul was charged with committing.

     In response to all of this, the joint dissent says that there
is‎no‎“robust‎history.”‎Dissenting‎Op.‎at‎37.‎‎But‎to‎reiterate,‎
the two most important military commission trials in U.S.
history were trials for conspiracy, which is not an
international law of war offense. From the beginning of the
Nation, Congress and the President have gone well beyond
international law when enacting legislation making offenses
triable by military commission.           To be sure, military
commissions were not employed by the United States during
the Korean War, the Vietnam War, or the Persian Gulf War.
See Hamdan v. Rumsfeld, 548 U.S. 557, 597 (2006) (plurality
opinion)‎(“The‎last‎time‎the‎U.S.‎Armed‎Forces‎used‎the‎law-
of-war military commission was‎during‎World‎War‎II.”).9 So
those wars do not supply us with any additional examples of
military commission trials, and thus do not tell us anything
one way or the other about trying conspiracy or other non-
international-law offenses before military commissions.

    But in the two most significant U.S. wars of the last 200
years – the Civil War and World War II – as well as in the
current war against al Qaeda and its associated forces, the

     9
       In the Korean War, General Douglas MacArthur – who was
serving as the head of the U.S. and United Nations forces in Korea
– issued regulations specifying conspiracy to commit war crimes as
an offense triable by military commission. See U.N. COMMAND,
RULES OF CRIMINAL PROCEDURE FOR MILITARY COMMISSIONS OF
THE UNITED NATIONS COMMAND at Rule 4 (Oct. 22, 1950)
(establishing‎ that‎ “all‎ attempts‎ to‎ commit,‎ or‎ conspiracies‎ and‎
agreements to commit . . . violations of the laws and customs of
war”‎committed‎ during‎ the‎ Korean‎ War‎ were‎ to‎ be‎ punishable‎ by‎
U.N. military commission). But no U.S. military commissions
ultimately were convened during that war.
                                19
U.S. has employed military commissions. And the most
important military commission trials during those wars were
trials for conspiracy, which is not an international law of war
offense. That historical and contemporary practice cannot be
airbrushed out of the picture. Prosecuting conspiracy and
other non-international-law-of-war offenses is not at the
periphery of U.S military commission history and practice.
Prosecuting conspiracy and other non-international-law-of-
war offenses lies at the core of U.S. military commission
history and practice.

     As the Supreme Court cautioned in Noel Canning, we
must‎ be‎ “reluctant to upset this traditional practice where
doing so would seriously shrink the authority that Presidents
have‎ believed‎ existed‎ and‎ have‎ exercised‎ for‎ so‎ long.”‎ Noel
Canning, 134 S. Ct. at 2573. Moreover, the Supreme Court
has explained that historical‎practice‎constitutes‎“an‎important‎
interpretive factor even when the nature or longevity of that
practice is subject to dispute, and even when that practice
began‎after‎the‎founding‎era.”‎Id. at 2560.

     In short, the text and original understanding of the
Constitution; the structure of the Constitution; landmark
Supreme Court precedent; the deeply rooted historical
practice of the Legislative Branch, as seen in federal statutes;
and the longstanding practice of the Executive Branch, as
seen in U.S. military commission practice stretching back
over two centuries, all point decisively to the same
conclusion: The war powers clauses of Article I of the
Constitution do not impose international law as a constraint
on Congress’s‎ authority‎ to‎ establish‎ offenses‎ triable‎ by‎
military commission.
                                    20
                                    II

     Bahlul also contends that Article III of the U.S.
Constitution confines U.S. military commissions to
international law of war offenses.

     This‎ iteration‎ of‎ Bahlul’s argument begins with the
premise that Article III vests the judicial power in Article III
courts and requires crimes to be tried by jury, not before
military commissions.10 Based solely on the text of Article
III, Bahlul might have a point. But the Supreme Court has
long recognized an exception to Article III for military
commissions to try enemy war crimes. See Ex Parte Quirin,
317 U.S. 1, 38-45 (1942); see also Hamdan v. Rumsfeld, 548
U.S. 557 (2006).

     Exceptions to Article III, including the exception for
military commissions, are established and interpreted in light
of historical practice. See Northern Pipeline Construction Co.
v. Marathon Pipe Line Co., 458 U.S. 50, 64 (1982) (plurality
opinion) (“[T]he literal command of Art. III . . . must be
interpreted in light of the historical context in which the
Constitution was written, and of the structural imperatives of
the‎ Constitution‎ as‎ a‎ whole.”);‎ Quirin 317‎ U.S.‎ at‎ 39‎ (“[I]t‎
was not the purpose or effect of § 2 of Article III, read in the
light of the common law, to enlarge the then existing right to
a‎ jury‎ trial.”);‎ see also Stern v. Marshall, 564 U.S. 462,
504-05 (2011)‎(Scalia,‎J.,‎concurring)‎(“[A]n Article III judge
is required in all federal adjudications, unless there is a firmly
established historical practice to the contrary.”);‎see generally

     10
         See U.S. CONST. art.‎ III,‎ §‎ 1‎ (“The‎ judicial‎ Power of the
United‎States,‎shall‎be‎vested‎.‎.‎.‎.”);‎id. §‎2,‎cl.‎3‎(“The‎Trial‎of‎all‎
Crimes, except in Cases of Impeachment, shall be by
Jury‎.‎.‎.‎.”).
                               21
Zivotofsky v. Kerry, 135 S. Ct. 2076, 2091, slip op. at 20
(2015) (“In‎ separation-of-powers cases this Court has often
put significant weight upon historical‎ practice.”) (internal
quotation marks omitted); Youngstown Sheet & Tube Co. v.
Sawyer, 343 U.S. 579, 610 (1952) (Frankfurter, J.,
concurring)‎ (“Deeply‎ embedded‎ traditional‎ ways‎ of‎
conducting government cannot supplant the Constitution or
legislation, but they give meaning to the words of a text or
supply‎ them.”);‎ The Pocket Veto Case, 279 U.S. 655, 689
(1929)‎ (“Long‎ settled‎ and‎ established‎ practice‎ is‎ a‎
consideration of great weight in a proper interpretation of
constitutional provisions of this character.”);‎ McCulloch v.
Maryland,‎ 17‎ U.S.‎ 316,‎ 401‎ (1819)‎ (“[A]‎ doubtful‎ question,‎
one on which human reason may pause, and the human
judgment be suspended, in the decision of which the great
principles of liberty are not concerned, but the respective
powers of those who are equally the representatives of the
people, are to be adjusted; if not put at rest by the practice of
the government, ought to receive a considerable impression
from‎that‎practice.”).

     In this context, if historical practice demonstrates that an
offense is triable by U.S. military commission, that history
resolves the Article III issue. As explained in Part I of this
opinion, the history of U.S. military commissions trying non-
international-law-of-war offenses is extensive and dates from
the beginning of the Republic. That historical practice
therefore amply demonstrates that Article III is not a barrier to
U.S. military commission trials of non-international-law-of-
war offenses, including the offense of conspiracy to commit
war crimes.

     Notwithstanding that history, Bahlul says that Quirin
already considered the military commission exception to
                                    22
Article III and limited the exception to international law of
war offenses.

      Bahlul’s‎ reading‎ of‎ Quirin is incorrect. In Quirin, the
Nazi saboteur defendants claimed that they had a right under
Article III to be tried by jury in an Article III federal court and
therefore could not be tried by military commission. At some
length, the Quirin Court specifically considered and rejected
the defendants’‎Article‎III‎objection.‎‎See Quirin, 317 U.S. at
38-45.11 The Court explained that Article III did not “enlarge
the‎ then‎ existing‎ right‎ to‎ a‎ jury‎ trial”‎ beyond‎ the‎ right‎ as‎ it‎
existed at common law. Id. at 39. Because the common law
did not preclude trial by military commission for war crimes,
Article‎ III‎ “cannot‎ be‎ taken‎ to‎ have‎ extended‎ the‎ right‎ to‎
demand a jury to trials by military commission, or to have
required that offenses against the law of war not triable by
jury‎at‎common‎law‎be‎tried‎only‎in‎the‎civil‎courts.”‎‎ Id. at
40.

      As explained above, in reaching its conclusion on the
Article III issue, the Quirin Court emphasized that Congress –
exercising its Article I powers – had made spying an offense
triable by military commission since the earliest days of the
Republic.‎ ‎ The‎ Court‎ stated‎ that‎ the‎ early‎ Congress’s‎
enactment‎ of‎ the‎ spying‎ statute‎ “must‎ be‎ regarded‎ as‎ a‎
contemporary‎construction”‎of‎Article‎III‎“as‎not‎foreclosing‎
trial by military tribunals, without a jury, of offenses against
the law of war committed by enemies not in or associated
with‎ our‎ Armed‎ Forces.”‎ ‎ Id. at‎ 41.‎ ‎ “Such‎ a‎ construction,”‎
the‎Court‎said,‎“is‎entitled‎to‎the‎greatest‎respect.”‎‎Id. at 41-
42.

     11
       The Court also referred to the Fifth and Sixth Amendments
when talking about Article III, but the Court analyzed them
together. For ease of reference, we will refer only to Article III.
                                 23

     The‎Supreme‎Court’s‎analysis in Quirin is instructive for
present purposes because, as noted above, the offense of
spying on which the Quirin Court relied to answer the Article
III objection was not (and is not) an offense under the
international law of war. It thus makes little sense to read
Quirin as barring military commission trials of non-
international-law-of-war offenses when Quirin, in rejecting a
jury trial objection to military commissions, expressly relied
on a longstanding statute making spying – a non-
international-law-of-war offense – triable by military
commission.

     In addition, as previously discussed, nothing about the
Court’s‎ reasoning‎ in‎ Quirin rested on whether the offense
tried by a military commission was an international law of
war offense. The Court never suggested that military
commissions are constitutionally permitted only for
international law of war offenses. Nor has the Court ever said
anything like that in its several later military commission
cases. One would have expected the Court to say as much if
the Court actually thought as much.

     To be sure, the Quirin Court referred to international law
authorities. But as noted above, the Court discussed those
authorities‎ in‎ part‎ because‎ an‎ offense’s‎ status‎ as‎ an‎
international law offense is sufficient but not necessary to
make an offense triable by military commission under 10
U.S.C.‎ §‎ 821,‎ the‎ statute‎ that‎ used‎ the‎ broad‎ term‎ “law‎ of‎
war”‎to‎define‎offenses‎triable‎by‎military‎commission.‎

   In short, Article III does not limit U.S. military
commissions to international law of war offenses or otherwise
                                24
foreclose trial of the offense of conspiracy to commit war
crimes before U.S. military commissions.12

     All of that said, the Constitution does not grant Congress
unlimited authority to designate crimes as triable by military
commission. At oral argument, the Government stated that
the charges must at least involve an enemy combatant who
committed a proscribed act during or in relation to hostilities
against the United States. See Tr. of Oral Arg. at 37. In
general, if an offense is an international law of war offense or
has historically been tried by U.S. military commission, that is
sufficient to‎ uphold‎ Congress’s‎ constitutional‎ authority‎ to‎
make the offense triable by military commission. See
generally Quirin, 317 U.S. at 24-48. As Winthrop explained,
the war crimes triable by U.S. military commission are
“derived‎ from‎ International‎ Law,‎ supplemented‎ by‎ acts‎ and‎
orders‎of‎the‎military‎power‎and‎a‎few‎legislative‎provisions.”
WILLIAM WINTHROP, MILITARY LAW AND PRECEDENTS 773
(rev. 2d ed. 1920).

    But is one of those conditions necessary? In other words,
what if an offense is neither an international law of war
offense nor historically rooted in U.S. military commission
practice? Consider a hypothetical new statute that makes
cyber-attacks by enemy forces a war crime triable by military
commission. Quirin stated‎ that‎ Article‎ III‎ does‎ “not‎ restrict‎
whatever authority was conferred by the Constitution to try
offenses‎against‎the‎law‎of‎war‎by‎military‎commission,”‎and‎
does‎not‎bar‎“the‎practice‎of‎trying,‎before‎military‎tribunals‎
without a jury, offenses committed by enemy belligerents
    12
         Bahlul also has raised equal protection and First
Amendment challenges to his conviction. Those arguments are
frivolous, for reasons explained in Al Bahlul v. United States, 767
F.3d 1, 75-76 (D.C. Cir. 2014) (en banc) (separate opinion of
Kavanaugh, J.).
                                 25
against‎the‎law‎of‎war.”‎‎Quirin, 317 U.S. at 45, 41. Perhaps
that language suggests that Article III permits what Article I
authorizes with respect to which enemy war crimes may be
tried by U.S. military commission. But we need not answer
that hypothetical in this case and need not define with
precision the outer limits of the Constitution in this context,
other than to say that international law is not such a limit.
Wherever one might ultimately draw the outer boundaries of
Congress’s‎ authority‎ to‎ establish‎ offenses‎ triable‎ by‎ military‎
commission, the historically rooted offense of conspiracy to
commit war crimes is well within those limits. An enemy of
the United States who engages in a conspiracy to commit war
crimes – in‎Bahlul’s‎case,‎by‎plotting‎with‎Osama‎bin‎Laden‎
to murder thousands of American civilians – may be tried by
a U.S. military commission for conspiracy to commit war
crimes.

                                 III

     In light of the importance of this case, and the serious and
passionate arguments advanced by the joint dissent, we close
with a few additional responses to points made by the joint
dissent.

     First, in reaching its conclusion, the joint dissent relies in
part on Hamdan v. Rumsfeld, 548 U.S. 557 (2006). That
reliance is misplaced. As relevant here, Hamdan was a
statutory‎ case‎ interpreting‎ the‎ phrase‎ “law‎ of‎ war”‎ in‎ 10‎
U.S.C. § 821. Nowhere did the Supreme Court ever say (or
even hint) that the United States Constitution imposed
international law as a limit on what offenses may be tried by
U.S.‎ military‎ commissions.‎ The‎ joint‎ dissent’s‎ citations‎ to‎
Hamdan therefore do not support its constitutional position.
                                26
     In fact, the Hamdan decision and its aftermath only
highlight the extraordinary nature‎ of‎ the‎ joint‎ dissent’s‎
position. In Hamdan, the Court confronted but ultimately did
not resolve the question of whether the relevant statute in
effect at the time, 10 U.S.C. § 821, barred military
commission trials of alleged war criminals for conspiracy.
But four of the Justices in the majority expressly invited
Congress to clarify the scope of military commission power.
Hamdan, 548 U.S. at 636 (Breyer, J., concurring, joined by
Kennedy, Souter, and Ginsburg, JJ.); id. at 653 (Kennedy, J.,
concurring in part, joined in relevant part by Souter,
Ginsburg,‎ and‎ Breyer,‎ JJ.).‎ ‎ ‎ In‎ response‎ to‎ the‎ Justices’‎
invitation, Congress and the President promptly enacted new
legislation to make crystal clear that conspiracy is an offense
triable by military commission. Military Commissions Act of
2006, Pub. L. No. 109-366, 120 Stat. 2600, 2625, 2630
(expressly authorizing trials before military commissions for
conspiracy offenses).

     A decade after Hamdan, Bahlul and the joint dissent have
now come back with a novel and extraordinary constitutional
interpretation that would thwart the considered wartime
decisions of two Congresses and two Presidents – decisions
invited by the Supreme Court in Hamdan – to authorize
military commission trials of conspiracy offenses. Under the
joint‎dissent’s‎theory,‎the‎congressional‎action‎invited‎by‎the‎
Supreme Court was all a waste of time because U.S. military
commissions are constitutionally barred from trying the
offense of conspiracy, regardless of statutory authorization.
But in Hamdan, not a single Justice hinted at a lurking
constitutional problem with trying conspiracy offenses before
military commissions (nor did Hamdan himself in his
arguments to the Supreme Court, either directly or through a
constitutional avoidance argument). To be sure, the Hamdan
decision does not formally preclude the Supreme Court from
                               27
now returning to the scene and finding a previously missed
constitutional problem with trying conspiracy offenses by
military commission. But in this wartime context, one should
not lightly assume that the Supreme Court expressly
encouraged the political branches to launch into an utterly
meaningless, decade-long exercise.

    Second,‎the‎joint‎dissent‎says:‎“It‎is‎not‎international‎law,‎
however, that constrains Congress’s‎ authority‎ here‎ – it is
Article‎III.”‎‎Dissenting‎Op.‎at‎46.‎That‎sentence‎glides‎over‎
the key question. The question is whether Article III (or
Article I) incorporates international law as a constraint on
U.S. military commissions. The joint dissent says yes. But
the constitutional text and structure, Supreme Court
precedents, and deeply rooted U.S. history tell us that the
answer is no.

     Of course, the consistent U.S. history is the consistent
U.S. history for a reason. As explained above, the
consequences for the United States of judicially incorporating
international law into the U.S. Constitution would be deeply
problematic and run afoul of our most fundamental
constitutional principles and traditions. International law
often embodies a majority or consensus view of nations.
Does the United States Constitution really allow foreign
nations, through the guise of international law, to set
constitutional limits enforceable in U.S. courts against the
U.S.‎ war‎ effort?‎ ‎ Under‎ Bahlul’s‎ argument,‎ and‎ under the
theory advanced by the joint dissent, the answer would be yes.
We think not. We see no basis in U.S. law, precedent, or
history – not to mention, common sense – for that position.
To‎ paraphrase‎ Justice‎ Jackson,‎ the‎ Constitution‎ is‎ not‎ “a‎
suicide pact.”‎‎Terminiello v. Chicago, 337 U.S. 1, 37 (1949)
(Jackson, J., dissenting).
                               28
     To be sure, the Judiciary plays a critical role in enforcing
constitutional and statutory limits in justiciable wartime cases,
and this Court must not hesitate (and has not hesitated) in
doing so, even when the consequences are significant. See
Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579
(1952); Al Bahlul v. United States, 767 F.3d 1 (D.C. Cir.
2014) (en banc) (Ex Post Facto Clause bars Congress and the
President from making material support for terrorism a war
crime that can be retroactively prosecuted before a military
commission); Hamdan v. United States, 696 F.3d 1238 (D.C.
Cir. 2012) (same, via constitutional avoidance doctrine). But
in this case, neither Article I nor Article III confines Congress
to international law of war offenses when Congress
establishes war crimes triable by military commission.

     To be clear, we take no position on the policy question of
whether the U.S. Government should use military
commissions to try the offense of conspiracy or other non-
international-law-of-war offenses, or indeed whether the
Government should use military commissions at all. That
policy decision belongs first to Congress and the President in
the legislative process, and then to the President in the
exercise of his or her Commander-in-Chief power. Likewise,
we take no position on the general question of when and how
Congress and the President should weigh international law
principles in making those decisions. International law is
important, and the political branches have good reason to
adhere to international law when determining what offenses
will be tried before U.S. military commissions. But
international law has its own enforcement mechanisms. The
federal courts are not roving enforcers of international law.
And the federal courts are not empowered to smuggle
international law into the U.S. Constitution and then wield it
as a club against Congress and the President in wartime.
                              29
     Third, the joint dissent seeks to explain away the history
and practice of U.S. military commissions. But that effort is
entirely unpersuasive.

     In the face of the deeply rooted U.S. history and practice
of trying conspiracy offenses by military commission, the
joint dissent had two options.          It could discount the
importance of history to the constitutional analysis, and try to
explain that the constitutional text and structure matter most
here. The joint dissent did not choose that approach, no doubt
because the constitutional text and structure also show what
the history shows: that international law is not a constraint on
Congress when Congress determines which offenses may be
tried by military commission.

     Alternatively, the joint dissent could attack the history
head-on on the theory that the history does not actually show
what it seems to show. That is the route that the joint dissent
chose. But it does not work. Consider all of the contortions
the joint dissent has to make in attempting to wriggle out of
the history. First, faced with the historical fact that Congress
since the Founding has consistently made non-international-
law offenses triable by military commission, the joint dissent
unconvincingly posits that those Congresses all mistakenly
believed that those offenses actually were international law
offenses (even though they were not and even though there is
no persuasive evidence that Congress thought they were). See
Dissenting Op. at 34-35. Second, faced with the historical
fact‎that‎the‎Executive‎Branch’s‎two‎most‎important military
commissions in the history of the country were trials of
conspiracy offenses, which are not international law offenses,
the joint dissent implausibly suggests that the Lincoln case
was not really a conspiracy case (even though it plainly was),
and it notes that the conspiracy charges against the eight
Nazis at issue in Quirin were never directly reviewed by a
                               30
court (even though the relevant point is that the military
commission trial of the Nazis for conspiracy remains a central
part of Executive Branch historical practice). See id. at 37-39,
42-44. Third, faced with the fact that the Supreme Court
relied on a non-international-law offense, spying, in its
landmark Quirin decision upholding military commissions,
the joint dissent seeks to sweep that inconvenient snippet
under the rug by suggesting that the Court mistakenly
believed that spying was an international law offense (even
though there is no persuasive evidence that the Court actually
thought as much). See id. at 25-26.

     The bottom line here is that the history matters, the
history is overwhelming, and the history devastates the joint
dissent’s‎position.‎

     Fourth, in justifying its position, the joint dissent posits a
hypothetical of non-U.S.-citizens living together in an
apartment in Virginia with pipe bombs, al Qaeda propaganda,
and a map of the Washington Metro. The joint dissent says it
would‎be‎“dangerous”‎to‎apprehend‎such‎a‎group‎and‎then‎try‎
them for conspiracy before a military commission.
Dissenting Op. at 63-64. We are mystified by the joint
dissent’s‎apparent‎belief‎that‎this‎is‎a‎helpful‎hypothetical‎for‎
its position. We take it that the point of the hypothetical is to
suggest that military commissions should not be used to try
non-citizen enemy terrorists who are (i) captured in the
United States (ii) before they commit their planned attacks.
Of course, the current war has no such neat geographical
boundaries. And neither did World War II, for that matter.
After all, the Nazi saboteurs were captured in the United
States before their planned attacks on U.S. facilities. They
were then prosecuted before U.S. military commissions. And
if Mohamad Atta and his fellow attackers had been captured
on the night of September 10, 2001, in Portland, Maine, and
                              31
elsewhere, and then tried before congressionally authorized
U.S. military commissions for conspiracy, we certainly would
not‎have‎characterized‎that‎scenario‎as‎“dangerous.”

     Fifth, the joint dissent insists that the mission of the
military is to defeat enemies on the battlefield, not to punish
enemy wrongdoers. See Dissenting Op. at 49-50. The
dissent’s‎effort‎to‎define‎U.S.‎military‎strategy‎in‎that‎way‎is‎
both legally and factually flawed. As the Supreme Court has
long recognized, including in landmark cases such as Hamdi,
war is waged not only by killing enemy combatants, but also
by surveilling, capturing, and detaining enemy forces, and by
trying unlawful enemy combatants for war crimes. And in the
current war, the modus operandi of the enemy is to target
citizens; to frighten, unsettle, disrupt, and demoralize; to
make normal peaceful life impossible and carnage routine. In
response‎ to‎ the‎ enemy’s‎ tactics,‎ two‎ Congresses‎ and‎ two‎
Presidents – like their predecessors throughout U.S. history –
have determined that employing military commissions to try
unlawful enemy combatants for their war crimes is an
important part of the overall war effort. The Constitution
assigns that question of military strategy to Congress and the
President, not to the joint dissenters.

     Sixth, and relatedly, in seeking to minimize the
consequences of its theory, the joint dissent suggests that
military commissions are not essential to the U.S. war effort
because the U.S. Government can simply try al Qaeda war
criminals in federal courts, including for conspiracy to
commit war crimes. See, e.g., Dissenting Op. at 1, 47-48.
With all respect, the joint dissent has no business making such
a statement. It has no basis to express such confidence and no
relevant expertise on that question of wartime strategy.
Unlike the joint dissenters, Presidents Bush and Obama, as
well as the two Congresses in 2006 and 2009, determined that
                               32
the ordinary federal court process is not suitable for trying
certain enemy war criminals. The only question for us as
judges is one of law: whether the U.S. Constitution permits
that policy choice by Congress and the President. If the
answer were no, then we would enforce the Constitution. Cf.
Hamdi v. Rumsfeld, 542 U.S. 507, 577 (2004) (Scalia, J.,
dissenting). But here, the answer is yes.

                             ***

      We‎ vote‎ to‎ affirm‎ Bahlul’s‎ conviction‎ for‎ conspiracy
to commit war crimes.
     MILLETT, Circuit Judge, concurring: “[T]here is no
liberty if the power of judging be not separated from the
Legislative and Executive powers.” THE FEDERALIST NO. 78,
at 425 (Alexander Hamilton) (E.H. Scott ed. 1898) (citation
omitted). Under our system of separated powers, that means
that the Judicial Branch bears both distinct responsibilities
and distinct constraints. In particular, the Judicial Branch
must declare and enforce the Constitution’s limitations
against the actions of the Political Branches in cases when
that is necessary. And we must not do so when it is not
necessary. “After all, a longstanding principle of judicial
restraint requires that courts avoid reaching constitutional
questions in advance of the necessity of deciding them.” 1

     Pursuant to the Military Commissions Act of 2006
(“2006 Act”), Pub. L. No. 109-366, 120 Stat. 2600, a military
commission found petitioner Hamza Ahmad Suliman al
Bahlul guilty of conspiracy to violate the law of war, in
violation of 10 U.S.C. § 950v(b)(28). The parties framed for
our review the important constitutional questions of whether a
conviction for inchoate conspiracy by an Article I military
commission either exceeds Congress’s legislative authority
under Article I or violates Article III’s assignment of the
judicial power to the federal courts.

    I would decline to resolve those constitutional questions
because they are not directly presented by this case. First,
Bahlul forfeited those challenges by failing to raise them



1
  Camreta v. Greene, 563 U.S. 692, 705 (2011) (internal quotation
marks and citation omitted); see also Ashwander v. Tennessee
Valley Authority, 297 U.S. 288, 346–347 (1936) (Brandeis, J.,
concurring) (explaining that courts should not “anticipate a question
of constitutional law in advance of the necessity of deciding it”;
neither should they “formulate a rule of constitutional law broader
than is required by the precise facts to which it is to be applied”).
                                 2
before the military commission, making plain-error review
appropriate.

     Second, whatever broad constitutional issues may lurk
within the 2006 Act, Bahlul challenges only his judgment of
conviction, and thus the application of the 2006 Act’s
conspiracy provision to him in this prosecution. See Oral
Arg. Tr. 6; Pet. Br. 57. And the conspiracy for which Bahlul
was convicted rested on proof of more statutory elements than
ordinary inchoate conspiracy requires, including intent to
further the commission of war crimes, Pet. Supp. App. 137,
and proof of an overt act in furtherance of a violation of the
law of war, id. In addition, the conspiracy’s objects included
completed war crimes. Id.

     Third, the specific findings made by the commission, on
which Bahlul’s conviction rests, largely eliminated the gap
between his conviction and those types of conspiracies that
are indisputably triable by military commission. Whatever
remaining distance Congress might have closed in an exercise
of its power to define and punish violations of the law of
nations does not, in my view, amount to plain constitutional
error.

     Finally, I join the court’s determination that Bahlul’s
First Amendment and Equal Protection claims are
foreclosed. 2




2
  I refer to the defendant as Bahlul, rather than al Bahlul, because
that is the appellation employed by his counsel on his behalf.
                               3
                               I

                               A

     This case concerns Bahlul’s conviction by a military
commission of conspiracy to violate the law of war, as that
offense is defined in 10 U.S.C. § 950v(b)(28). A person
commits conspiracy under Section 950v(b)(28) if he
“conspires to commit one or more substantive offenses triable
by military commission under this chapter, and * * *
knowingly does any overt act to effect the object of the
conspiracy.” 10 U.S.C. § 950v(b)(28). The substantive
offenses triable by military commission under the chapter
include murder of protected persons, attacking civilians,
attacking civilian objects, murder in violation of the law of
war, destruction of property in violation of the law of war,
terrorism, and providing material support for terrorism. See
id. § 950v(b)(1), (2), (3), (15), (16), (24) & (25). The 2006
Act further provides that conspiracy “shall be punished, if
death results to one or more of the victims, by death or other
such punishment as a military commission under this chapter
may direct, and, if death does not result to any of the victims,
by such punishment, other than death, as a military
commission under this chapter may direct.” Id. § 950v(b).

     In what is known as the “Define and Punish Clause,”
Article I of the Constitution empowers Congress to “define
and punish * * * Offences against the Law of Nations.” U.S.
CONST., Art. I, § 8, cl. 10. The Supreme Court has explained
that “[o]ffences * * * against the law of nations, cannot, with
any accuracy, be said to be completely ascertained and
defined in any public code recognized by the common
consent of nations.” United States v. Smith, 18 U.S. 153, 158
(1820). Thus, “there is a peculiar fitness in giving the power
to define as well as to punish” to Congress, “and there is not
                                4
the slightest reason to doubt that this consideration had very
great weight in producing the phraseology in question.” Id.;
see Ex parte Quirin, 317 U.S. 1, 28 (1942).

      At the same time, Congress’s power to punish offenses
by military commission is constrained by the Constitution’s
Judicial Power Clause, Art. III, § 2, cl. 1. That Clause
provides that “[t]he judicial Power shall extend to all Cases,
in Law and Equity, arising under this Constitution, the Laws
of the United States, and Treaties made, or which shall be
made, under their Authority,” and “to Controversies to which
the United States shall be a Party.” Id. Those “Cases” and
“Controversies” include criminal prosecutions. See United
States ex rel. Toth v. Quarles, 350 U.S. 11, 15 (1987). If a
suit falls within the judicial power, then “the responsibility for
deciding that suit rests with Article III judges in Article III
courts,” and the Constitution forbids Congress to assign its
resolution to another tribunal. See Stern v. Marshall, 564
U.S. 462, 484 (2011).

                                B

     While our prior en banc opinion catalogued the factual
background of this case, see Bahlul v. United States (Bahlul
I), 767 F.3d 1, 5–8 (D.C. Cir. 2014) (en banc), portions of that
factual history help to frame the legal questions that Bahlul
presents.

     Bahlul is a native of Yemen. In the late 1990s, he
traveled to Afghanistan to join al Qaeda, and there he met
Usama bin Laden. On October 12, 2000, al Qaeda attacked
the USS Cole, killing seventeen American sailors and injuring
thirty-nine others. Bahlul created a recruiting video for al
Qaeda celebrating that attack, which he considered one of the
best recruiting videos al Qaeda had produced. Pet. App. 134;
see Bahlul I, 767 F.3d at 5.
                              5
     Bin Laden subsequently appointed Bahlul his personal
assistant and secretary for public relations. Bahlul actively
prepared for al Qaeda’s attacks on the United States on
September 11, 2001. He arranged the loyalty oaths and
prepared “martyr wills” for Mohamed Atta and Ziad al Jarrah,
two of the hijackers who flew planes into the World Trade
Center. Those “martyr wills” were propaganda declarations
made in preparation for the attack and in which Atta and al
Jarrah documented their and al Qaeda’s roles in the atrocities.
Bahlul also provided research to bin Laden regarding the
economic effects of the attacks.          In addition, Bahlul
volunteered to participate in the 9/11 attacks himself, but bin
Laden thought he was too important to lose. Just before 9/11,
Bahlul evacuated al Qaeda’s headquarters in Afghanistan with
bin Laden and other senior al Qaeda leaders. Bahlul I, 767
F.3d at 6. After the attacks, Bahlul fled to Pakistan, where he
was captured and turned over to the United States military.
Id. at 6.

     As relevant here, the United States charged Bahlul under
the 2006 Act with conspiracy to commit war crimes. See 10
U.S.C. § 950v(b)(28). Bahlul was tried before a military
commission convened at Guantanamo Bay. During the trial,
Bahlul “flatly refused to participate in the military
commission proceedings and instructed his trial counsel not to
present a substantive defense.” Bahlul I, 767 F.3d at 10. At
no time did he raise any argument that Congress lacked the
constitutional power to authorize a trial by military
commission for conspiracy, or that in doing so, Congress ran
afoul of the Define and Punish Clause or the Judicial Power
Clause.

     Before its deliberations, the commission was instructed
that, to convict Bahlul of conspiracy under the 2006 Act, it
must find “beyond a reasonable doubt” that Bahlul “entered
                              6
into an agreement” with other members of al Qaeda to
commit a substantive offense under the Act, “knew the
unlawful purpose of the agreement and joined in it willingly,”
and “knowingly committed” an overt act to bring about one of
the objects of the agreement. Pet. Supp. App. 137. The
military commission subsequently found Bahlul guilty of
conspiracy under 10 U.S.C. § 950v(b)(28). In so doing, the
commission specifically found that Bahlul committed ten
overt acts as part of the conspiracy:

   1. Traveled to Afghanistan with the purpose and intent of
      joining al Qaeda;
   2. Met with Saif al’Adl, the head of the al Qaeda
      Security Committee, as a step toward joining the al
      Qaeda organization;
   3. Underwent military-type training at an al Qaeda
      sponsored training camp then located in Afghanistan;
   4. Pledged fealty, or “bayat,” to the leader of al Qaeda,
      Usama bin Laden, joined al Qaeda, and provided
      personal services in support of al Qaeda;
   5. Prepared and assisted in the preparation of various
      propaganda products, including the video “The
      Destruction of the American Destroyer U.S.S. Cole,”
      to solicit material support for al Qaeda, to recruit and
      indoctrinate personnel to the organization and
      objectives of al Qaeda, and to solicit, incite and advise
      persons to commit Terrorism;
   6. Acted as personal secretary and media secretary of
      Usama bin Laden in support of al Qaeda;
   7. Arranged for Muhammed Atta, also known as Abu
      Abdul Rahman al Masri, and Zaiad al Jarrah, also
      known as Abu al Qa’qa al Lubnani, to pledge fealty or
      “bayat,” to Usama bin Laden;
   8. Prepared the propaganda declarations styled as martyr
      wills for two of the 9/11 hijackers, Muhammed Atta
                               7
       and Ziad al Jarrah, in preparation for the acts of
       terrorism perpetrated by them in the United States on
       September 11, 2001;
   9. At the direction of Usama bin Laden, researched the
       economic effects of the September 11, 2001, attacks
       on the United States, and provided the results to
       Usama bin Laden; and
   10. Operated and maintained data processing equipment
       and media communications equipment for the benefit
       of Usama bin Laden and other members of the al
       Qaeda leadership.

Pet. App. at 116–117.

      The commission also found Bahlul guilty of conspiracy
to commit seven charged object offenses: (i) murder of
protected persons, (ii) attacking civilians, (iii) attacking
civilian objects, (iv) murder in violation of the law of war, (v)
destruction of property in violation of the law of war, (vi)
terrorism, and (vii) providing material support for terrorism.
Pet. App. 115; see 10 U.S.C. § 950(v)(b)(1), (3), (15), (16),
(24) & (25). The military commission sentenced Bahlul to
life imprisonment. Pet. App. 86.

                               II

                               A

      Before wading into any constitutional dispute, courts
must first decide how deeply they should go—that is, which
standard of review should apply. Those review standards are
critical components of our justice system because they
promote fairness, stability, and finality within the judicial
process, and they give effect to the relative expertise of both
the appellate court and the tribunals whose judgments are
under review. See Puckett v. United States, 556 U.S. 129, 134
                                8
(2009); United States v. Frady, 456 U.S. 152, 163 (1982)
(Standards of review “encourage all trial participants to seek a
fair and accurate trial the first time around[.]”).

     Ordinarily, questions of constitutional law in criminal
cases are decided de novo, and we plunge into plenary review.
See, e.g., United States v. Straker, 800 F.3d 570, 629 (D.C.
Cir. 2015). But this case is not ordinary. Bahlul seeks to
overturn his conviction on the basis of constitutional
arguments that he could have made before the military
commission, but did not. Bahlul nonetheless insists that we
must consider his challenges de novo. See Pet. Br. 41.

     Bahlul is wrong, in my view. Appellate courts are
supposed to be courts of review, not first view. See
Zivotofsky ex rel. Zivotofsky v. Clinton, 132 S. Ct. 1421, 1430
(2012). And “‘[n]o procedural principle is more familiar
* * * than that a constitutional right,’ or a right of any other
sort, ‘may be forfeited in criminal as well as civil cases by the
failure to make timely assertion of the right before a tribunal
having jurisdiction to determine it.’” United States v. Olano,
507 U.S. 725, 731 (1993) (quoting Yakus v. United States,
321 U.S. 414, 444 (1944)); United States v. Baucum, 80 F.3d
539, 541 (D.C. Cir. 1996) (noting “established Supreme Court
precedent declining to address constitutional questions not put
in issue by the parties”); see also, e.g., United States v. David,
96 F.3d 1477, 1482 (D.C. Cir. 1996) (criminal defendant
waived constitutional challenge under the Commerce Clause).

      In a civil case, Bahlul’s forfeiture would be fatal; we
would not review his newly raised claims at all. See
Nemariam v. Federal Democratic Republic of Ethiopia, 491
F.3d 470, 483 (D.C. Cir. 2007) (“[A]bsent exceptional
circumstances, the court of appeals is not a forum in which a
litigant can present legal theories that it neglected to raise in a
                               9
timely manner in proceedings below.”) (internal quotation
marks omitted). Criminal cases, however, are different.
Typically, when a criminal defendant forfeits a challenge,
even a constitutional one, an appellate court will still review
the claim for “plain error.” FED. R. CRIM. P. 52(b); see, e.g.,
United States v. Cotton, 535 U.S. 625, 631–632 (2002). A
forfeited error warrants reversal as “plain error” only if the
error was “clear” or “obvious” at the time it was made.
Olano, 507 U.S. at 734. Even then, the decision whether to
correct the forfeited error lies “within the sound discretion of
the court of appeals.” Id. at 732. Courts should not exercise
that discretion unless the error “seriously affect[ed] the
fairness, integrity or public reputation of judicial
proceedings.” United States v. Young, 470 U.S. 1, 15 (1985);
see also FED. R. CRIM. P. 52(b) (“A plain error that affects
substantial rights may be considered even though it was not
brought to the court’s attention.”) (emphasis added).

      While my colleagues believe that the constitutional
importance of the issues presented and their implications
warrant a discretionary exercise of de novo review, see
Wilkins Concurring Op. at 1; Joint Dissent at 4–9; see also
Kavanaugh Concurring Op. at 3 n.1, limiting appellate review
to plain errors when a criminal defendant fails to object at
trial serves a vital function within the criminal justice system.
The plain-error rule “induce[s] the timely raising of claims
and objections,” which in turn affords the trial court the
opportunity both “to determine the relevant facts and
adjudicate the dispute” in the first instance and, if warranted,
to “correct or avoid the mistake so that it cannot possibly
affect the ultimate outcome.” Puckett, 556 U.S. at 134.

    The contemporaneous-objection rule also prevents a
defendant from “‘sandbagging’ the court—remaining silent
about his objection and belatedly raising the error only if the
                              10
case does not conclude in his favor,” Puckett, 556 U.S. at
134—which is exactly what Bahlul is doing.
“[E]ncourag[ing] all trial participants” instead “to seek a fair
and accurate trial the first time around” promotes fairness to
the court, to all of the parties, Frady, 456 U.S. at 163, and to
the public, as well as stability in the law. See generally Exxon
Shipping Co. v. Baker, 554 U.S. 471, 487 n.6 (2008)
(“[W]aiver and forfeiture rules * * * ensure that parties can
determine when an issue is out of the case, and that litigation
remains, to the extent possible, an orderly progression.”).

      As our prior en banc opinion explained, Bahlul “flatly
refused to participate in the military commission
proceedings,” and to the extent that he objected at all to his
trial, the objection “was couched entirely in political and
religious terms.” Bahlul I, 767 F.3d at 10; see id. at 7
(“Bahlul waived all pretrial motions, asked no questions
during voir dire, made no objections to prosecution evidence,
presented no defense and declined to make opening and
closing arguments.”).      Bahlul declared that he was a
“prisoner[] of war and legal combatant[] based on [his]
religion,” rejected the United States’ “earthly laws and
international earthly laws,” questioned “how can there be a
tribunal, a court, a complete court, and a fair court as long as
they do not—when they do not accept our rules, our laws,”
and then concluded that “there is going to be the tribunal of
God on the day of judgments.” Pet. App. 109–112.

    That generic diatribe against the proceedings writ large
did not preserve the specific constitutional challenges that
Bahlul now presses. His complaints were far “too general to
have alerted the trial court to the substance of [his] point,”
United States v. Bolla, 346 F.3d 1148, 1152 (D.C. Cir. 2003)
(Roberts, J.) (quotation marks omitted), or to have given the
court or opposing counsel any notice of the constitutional
                              11
character of his claim, see also United States v. Love, 593
F.3d 1, 11 (D.C. Cir. 2010) (defendant’s “general objection
* * * was insufficient to preserve his arguments for appeal”);
United States v. Breedlove, 204 F.3d 267, 270 (D.C. Cir.
2000) (an objection “couched in terms too general” to have
put the trial court on notice of “the substance of the [claim]”
was not preserved).

      To be sure, I do not believe a defendant must cite to any
particular case or style arguments in a particular way to
sufficiently preserve a claim. See United States v. Rashad,
396 F.3d 398, 401 (D.C. Cir. 2005). All Bahlul had to do was
“inform the court and opposing counsel of the ruling he
want[ed] the court to make and the ground for so doing.” Id.
But Bahlul failed to do even that. He did not so much as
mention the Constitution. He just categorically disdained the
trial process. Accordingly, I would hold Bahlul to the same
standard that courts apply every day to other criminal
defendants who fail to preserve claims, and would review his
new constitutional challenges only for plain error.

                              B

     To evade the consequences of his forfeiture, Bahlul tries
to package his Article III claim as a challenge to the military
commission’s subject-matter jurisdiction, presumably because
“defects in subject-matter jurisdiction require correction
regardless of whether the error was raised” below. Cotton,
535 U.S. at 630. That tactic fails. This Court has already
held that the 2006 Act “explicitly confers jurisdiction on
military commissions to try the charged offenses.” Bahlul I,
767 F.3d at 10 n.6. There thus should be no question that the
military commission acted within its statutorily assigned
jurisdiction.
                              12
     What Bahlul’s challenge really goes to is whether, in
authorizing a law-of-war military commission to decide the
conspiracy charge, Congress exceeded its constitutional
authority under either Article I’s Define and Punish Clause or
Article III’s Judicial Power Clause. In general, if a suit falls
within the judicial power, then “the responsibility for deciding
that suit rests with Article III judges in Article III courts.”
Stern, 564 U.S. at 484. But an exception exists for certain
criminal prosecutions—specifically, criminal violations of the
international laws of war—which constitutionally may be
tried before military commissions.           See Johnson v.
Eisentrager, 339 U.S. 763, 786 (1950) (“The jurisdiction of
military authorities, during or following hostilities, to punish
those guilty of offenses against the laws of war is long-
established.”).

     Bahlul argues that his prosecution for conspiracy before
the military commission did not fall within any such
exception because it did not charge a violation of the
international law of war. And because of that, Bahlul says, he
was constitutionally entitled to have the charges against him
brought before an Article III court.

     The problem for Bahlul’s effort to frame that argument
as jurisdictional is that “[e]ven the unconstitutionality of the
statute under which the proceeding is brought does not oust a
court of jurisdiction.” United States v. Williams, 341 U.S. 58,
65 (1951). As long as the military commission “exercises its
power under a presumptively valid federal statute, it acts
within its subject-matter jurisdiction[.]” Baucum, 80 F.3d at
540. Indeed, in this Court’s previous en banc decision, we
reviewed another separation-of-powers claim pressed by
Bahlul—his Ex Post Facto Clause claim—for plain error,
even though that challenge concerned the constitutionality of
the 2006 Act, and thus the power of the United States to
                               13
proceed against him. See Bahlul I, 767 F.3d at 10 & n.6; see
also Carmell v. Texas, 529 U.S. 513, 531 n.21 (2000) (the Ex
Post Facto Clause is in part “aimed at * * * reinforcing the
separation of powers”).

     Bahlul’s claims here have no more jurisdictional aspect
than did his ex post facto claims. His Define and Punish
Clause argument is a challenge to the constitutionality of the
2006 Act. So too is Bahlul’s Judicial Power Clause
argument: “The ‘Article III’ label changes nothing; by this
Clause, Article III restricts the Congress’s power, not the
power of the courts or military commissions.” Bahlul v.
United States (Bahlul II), 792 F.3d 1, 31 (D.C. Cir. 2015)
(Henderson, J., dissenting). To hold otherwise would mean
that “a court would be required to raise [a Judicial Power
Clause challenge] sua sponte each time it reviews a decision
of a non-Article III tribunal,” even if the parties do not contest
that issue. Id. at 32; see generally Baucum, 80 F.3d at 541
(Courts have “an obligation to address jurisdictional questions
sua sponte.”).

     In short, Bahlul’s “belated assertion of a constitutional
defect” does “not work to divest” the military commission of
its jurisdiction to try him. Baucum, 80 F.3d at 541.
Accordingly, his constitutional challenge to Congress’s
authorization of his conspiracy prosecution before a military
commission should be subject to the same contemporaneous-
objection requirement as any other constitutional claim.

                                C

                                1

    After that long preface, I arrive at the heart of Bahlul’s
argument for de novo review: He contends that a criminal
defendant can never forfeit an Article III structural claim.
                               14
Specifically, Bahlul argues that the Judicial Power Clause of
Article III prohibits Congress from assigning the trial of
criminal conspiracies to a non-Article III tribunal, and that
such a structural Article III claim is not subject to plain-error
review.

      For support, Bahlul points to the Supreme Court’s
decision in Commodity Futures Trading Commission v.
Schor, 478 U.S. 833 (1986). In that case, Schor challenged
the Commodity Futures Trading Commission’s jurisdiction
over certain common-law counterclaims in civil reparations
proceedings. Schor argued that Article III required that those
traditionally common-law claims be decided by the Judicial
Branch, not by an Executive Branch tribunal. Id. at 835–836.
While acknowledging that “Schor indisputably waived any
right he may have possessed [by] expressly demand[ing] that
[the other party] proceed on its counterclaim” before the
Commission, the Supreme Court addressed the merits of his
structural challenge de novo. Id. at 849–851. In so doing, the
Supreme Court explained that “Article III, § 1 safeguards the
role of the Judicial Branch in our tripartite system by barring
congressional attempts to transfer jurisdiction to non-Article
III tribunals for the purpose of emasculating constitutional
courts[.]” Id. at 850 (quotation marks omitted, alterations in
original). When that “structural principle is implicated in a
given case,” the Court added, traditional rules “of consent and
waiver cannot be dispositive” because those Article III
limitations “serve institutional interests that the parties cannot
be expected to protect.” Id. at 850–851 (quotation marks,
citations, and alterations omitted); see also Freytag v.
Commissioner of Internal Revenue, 501 U.S. 868, 880 (1991)
(“Neither Congress nor the Executive can agree to waive
* * * structural protection[s].”); Wellness Int’l Network, Ltd.
v. Sharif, 135 S. Ct. 1932, 1945 n.10 (2015) (“What Schor
                              15
forbids is using consent to excuse an actual violation of
Article III.”).

     Bahlul takes those passages to mean that an Article III
structural claim can never be forfeited, and that we are thus
obligated to review his claim de novo. That overreads Schor.
What the Supreme Court said is that “notions of consent and
waiver cannot be dispositive.” Schor, 478 U.S. at 851
(emphasis added). At most, that means that appellate courts
have discretion to hear unpreserved Article III structural
claims de novo in appropriate cases, not that they are
obligated to do so. Subsequent Supreme Court precedent
proves that point.

     To begin with, in Plaut v. Spendthrift Farm, Inc., 514
U.S. 211 (1995), the Supreme Court held that the Securities
Exchange Act’s requirement that federal courts reopen certain
final judgments in private civil actions violated Article III
because the Article III judicial power is the power to decide
cases conclusively. Id. at 213, 218. The government had
invoked Schor’s non-waiver language in defense of the
statute, reasoning that if the finality of federal court
judgments implicated Article III, then res judicata would not
be waivable either. Id. at 231. The Supreme Court gave no
quarter to that reading of Schor: “The proposition that legal
defenses based upon doctrines central to the courts’ structural
independence can never be waived simply does not accord
with our cases.” Id. What Schor meant, the Supreme Court
explained, was that a court could still “choose to consider his
Article III challenge,” notwithstanding a litigant’s consent to
an alternative tribunal, because when “‘Article III limitations
are at issue, notions of consent and waiver cannot be
dispositive[.]’” Id. at 232 (first emphasis added; quoting
Schor, 478 U.S. at 851).
                               16
     The Supreme Court reconfirmed twice just two Terms
ago that courts may treat Article III structural claims as
subject to waiver and forfeiture. In B&B Hardware, Inc. v.
Hargis Industries, Inc., 135 S. Ct. 1293 (2015), the Court held
that a decision by the Trademark Trial and Appeal Board—a
non-Article III tribunal—is entitled to the same preclusive
effect as a district court decision if the ordinary elements of
issue preclusion are met, id. at 1299. In so holding, the Court
eschewed consideration of any potentially “meritorious
constitutional objection” under Article III because that
argument was abandoned by Hargis Industries, and thus “it is
not before us.” Id. at 1304 (citing Plaut, 514 U.S. at 231–
232).

     Continuing that pattern, in Wellness International
Network, supra, the Court held that “Article III is not violated
when the parties knowingly and voluntarily consent to
adjudication by a bankruptcy judge” of a state-law claim that
arose independently of bankruptcy law, 135 S. Ct. at 1939. In
Stern v. Marshall, supra, the Court had held that, as a general
matter, Article III forbids bankruptcy courts to enter final
judgments on such claims, 564 U.S. at 500–501. Wellness,
however, created an exception to that general rule where both
parties consent to bankruptcy-court adjudication.

      Critically, at the end of its Wellness opinion, the Supreme
Court remanded the case to the Seventh Circuit to decide
whether Sharif’s consent was knowing and voluntary, and
whether “Sharif forfeited his Stern argument below.” 135 S.
Ct. at 1949. That remand would, of course, have been
pointless if Article III structural claims like the Stern claim
can never be waived or forfeited. See also Sharif, 135 S. Ct.
at 1949 (Alito, J., concurring in part and concurring in the
judgment) (“[R]espondent forfeited any Stern objection by
failing to present that argument properly in the courts below.
                              17
Stern vindicates Article III, but that does not mean that Stern
arguments are exempt from ordinary principles of appellate
procedure.”).

     Of course, as the panel majority and concurrence well
chronicled, the Supreme Court’s pronouncements in this area
have been far from crystalline. See Bahlul II, 792 F.3d at 3–
5; 23–24 (Tatel, J., concurring). But B&B Hardware and
Wellness have done much to lift the fog. I accordingly
conclude that Schor does not require us to wade into a
constitutional thicket and review de novo Bahlul’s forfeited
Article III structural challenge.

                              2

     I agree with my colleagues, however, that Schor affords
this Court some discretion to review a forfeited Article III
claim de novo. See Kavanaugh Concurring Op. at 3 n.1, Joint
Dissent at 4-6. But I would decline to exercise that discretion
in this case for three reasons.

     First, there is no structural reason to take up Bahlul’s
fight with the Political Branches. Unlike Schor, Freytag,
Stern, Plaut, B&B Hardware, and Wellness, which were all
civil cases, this is a criminal case. That distinction matters
because the consequences of forfeiture are materially different
in civil and criminal contexts. In civil cases, a claim that a
party waives or forfeits is generally gone for good. An
appellate court will not review it under any standard of
review. See Salazar ex rel. Salazar v. District of Columbia,
602 F.3d 431, 437 (D.C. Cir. 2010); Nemariam, 491 F.3d at
482–483; cf. Singleton v. Wulff, 428 U.S. 106, 121 (1976)
(noting rare “circumstances in which a federal appellate court
is justified in resolving an issue not passed on below, as
where the proper resolution is beyond any doubt * * * or
where injustice might otherwise result”).
                                18
     In addition, civil cases can pose the risk of parties
colluding and consenting to a non-Article III forum for
resolution of their dispute. Absent discretionary review, such
joint waivers of challenges to the judicial forum could
effectively strip Article III courts of the ability ever to address
the constitutionality of legislation reassigning the judicial
power.

      That perceived need to ensure some mechanism for
enforcing the separation of powers and protecting the judicial
power against incursions by the Political Branches seemingly
motivated Schor’s discretionary exception to traditional
principles of waiver and forfeiture in civil cases. As the
Supreme Court explained, Article III “limitations serve
institutional interests that the parties cannot be expected to
protect.” Schor, 478 U.S. at 851; see also Peretz v. United
States, 501 U.S. 923, 950 (1991) (“Article III serves as an
inseparable element of the constitutional system of checks and
balances by preserving the role of the Judicial Branch in our
tripartite system of government.”) (quotation marks omitted).

     Unlike civil cases, however, criminal cases like Bahlul’s
present no similar need to work around the ordinary
contemporaneous-objection rule. The whole reason my
colleagues and I are even debating the application of the
“plain-error” standard of review is that, in criminal cases,
forfeited claims are not really forfeited at all. They are still
subject to judicial review and decision; all that changes is the
level of scrutiny. See FED. R. CIV. P. 52(b); Olano, 507 U.S.
at 733–735. In other words, in criminal cases, a “forfeited”
Article III claim is still reviewed and decided; it is just harder
to win. See, e.g., Olano, 507 U.S. at 734 (“A court of appeals
cannot correct an error pursuant to Rule 52(b) unless the error
is clear under current law.”); In re Sealed Case, 573 F.3d 844,
851 (D.C. Cir. 2009) (“[A]n error can be plain if it violates an
                                 19
absolutely clear legal norm.”) (quotation marks omitted).
That means that, unlike civil cases, the availability of plain-
error review in criminal cases ensures that clear or obvious
usurpations of Article III will not escape judicial scrutiny,
regardless of whether a criminal defendant timely raised such
objections below.

     Likewise, even when a criminal defendant affirmatively
waives (rather than forfeits) a structural Article III challenge,
the argument may, if warranted, still be reviewed later
through the lens of an ineffective-assistance-of-counsel claim.
If the constitutional transgression is so clear that a failure to
raise it was not “within the range of competence demanded of
attorneys in criminal cases,” and if it prejudiced the
defendant’s case, see United States v. Streater, 70 F.3d 1314,
1318 (D.C. Cir. 1995) (quoting Hill v. Lockhart, 474 U.S. 52,
56, 59 (1985)), an appellate court may decide the
constitutional question. 3

3
  In a series of cases challenging the Federal Magistrates Act, Pub.
L. No. 90-578, 82 Stat. 1107–1119 (1968), the Supreme Court
addressed constitutional objections to adjudications by non-Article
III federal magistrate judges in criminal cases. However, none of
those cases presented a structural Article III question because the
district court’s de novo review ensured that the operative decision
was made by an Article III judge. See, e.g., Peretz, 501 U.S. at 937
(“[N]o * * * structural protections are implicated” because “[t]he
ultimate decision whether to invoke the magistrate’s assistance is
made by the district court, subject to veto by the parties.”)
(quotation omitted); United States v. Raddatz, 447 U.S. 667, 683
(1980) (The “delegation does not violate Art. III so long as the
ultimate decision is made by the district court.”); see also Gomez v.
United States, 490 U.S. 858, 874 (1989) (construing the Act not to
authorize magistrate judges to supervise jury selection in part
because the court “harbor[ed] serious doubts that a district judge
could review this function meaningfully”).
                              20
     Second, in almost all of the Supreme Court cases granting
review of a structural Article III question, the barrier to
judicial review was waiver, not forfeiture. See Wellness, 135
S. Ct. at 1939 (noting “the parties’ consent” to bankruptcy
court adjudication); Freytag, 501 U.S. at 878 (“[P]etitioners
gave their consent to trial before the Special Trial Judge.”);
Schor, 478 U.S. at 837 (Schor himself “invoked the
[Commission’s] reparations jurisdiction[.]”). The waivers
arose, moreover, because Congress designed the challenged
statutory schemes so that litigants would first choose to bring
their claim in a non-Article III forum. In that way, Congress
baked the barrier to judicial review right into the allegedly
Article III-circumventing statutory scheme, thus presenting
the question whether Congress could team up with litigants to
divert the judicial power to a non-Article III tribunal. See
Wellness, 135 S. Ct. at 1939 (considering “whether Article III
allows bankruptcy judges to adjudicate [Stern] claims with the
parties’ consent”); Schor, 478 U.S. at 851 (“[T]he parties
cannot by consent cure the constitutional difficulty.”).

    By definition, the constitutionality of such statutory
schemes could not be determined without bypassing the
element of private choice that Congress used to trigger the
non-Article III tribunal in the first instance. That presumably
is why the Supreme Court explained in Plaut that “[w]aiver
subject to the control of the courts themselves”—rather than
imposed by Congress—would be materially different to the
constitutional analysis, “would obviously raise no issue of
separation of powers, and would be precisely in accord with”
Schor. Plaut, 514 U.S. at 231–232 (emphasis added).

    This case, however, involves a forfeiture, not a waiver, of
an Article III objection that was fully available to Bahlul
throughout the military commission proceeding. Bahlul, like
criminal defendants generally, had every opportunity and
                              21
incentive to raise objections that (if successful) would have
foreclosed his conviction or would have provided grounds for
a full reversal on appeal. Indeed, criminal defendants as a
class are profoundly self-interested when it comes to
preserving substantial legal challenges to exercises of
prosecutorial power. Thus the risk that criminal defendants
will team up with the prosecution in a way that would
otherwise preclude judicial enforcement of the separation of
powers is something short of negligible.

     For those reasons, the contemporaneous-objection rule
does not pose the same practical barrier to constitutional
review in criminal cases that it did in Schor’s civil litigation
context. Instead, in criminal prosecutions, “the claims of
individuals * * * have been the principal source of judicial
decisions concerning separation of powers and checks and
balances.” Bond v. United States, 564 U.S. 211, 222 (2011).
Here as well, all that would be needed for a court to decide de
novo the structural Article III question that Bahlul belatedly
raises is for a defendant in one of the other pending military
commission proceedings to timely raise it as a defense to
prosecution in that forum.

     Third, Bahlul has identified no unusual obstacles or
exceptional circumstances that excuse his failure to raise his
Article III claim before the military commission. He had the
benefit of trained counsel and multiple procedural
opportunities to voice his constitutional objections. Bahlul’s
knowing and willful refusal to participate in his trial should
not now be rewarded by addressing his constitutional
arguments de novo rather than under plain-error review. To
the contrary, excusing Bahlul’s failure to bring his Article III
structural claim would encourage similar sandbagging
behavior from other military commission defendants. They
would have nothing to lose by first trying their chances before
                               22
the commission and, if unhappy with the results, pulling an
Article III challenge out of their pocket in the hope of trying
the case all over again in federal court (with the added benefit
of the prosecution’s hand having been revealed).

     Bahlul argues (Pet. Br. 37), and Judge Kavanaugh’s
concurring opinion agrees (at 3 n.1), that the government
failed to raise any forfeiture argument before the Court of
Military Commission Review, or to argue for plain-error
review, and thus it “has—in a word—forfeited [its] forfeiture
argument here,” Pet. Br. 37 (quoting Solomon v. Vilsack, 763
F.3d 1, 13 (D.C. Cir. 2014)); see also Joint Dissent at 2–4. I
read our precedent and the record differently.

     For starters, the rule that a party may forfeit a forfeiture
argument applies to the preservation of a substantive legal
claim in a civil case, like the discriminatory retaliation claim
that was at issue in Solomon, 763 F.3d at 13. The issue in this
criminal appeal, however, is not whether Bahlul’s
constitutional claims get reviewed at all—the special plain-
error rule in criminal cases ensures some type of review. The
only question is which standard of review governs the appeal,
and “[t]he Government cannot alter our standard of review—
by concession, inadvertence, poor oral advocacy or
otherwise.” Bahlul II, 792 F.3d at 32 n.3 (Henderson, J.,
dissenting); see United States v. Nueci-Pena, 711 F.3d 191,
196 n.5 (D.C. Cir. 2013) (reviewing for plain error although
the government “erroneously assert[ed] that de novo review
applie[d]”). That is because, as an appellate court, this court
“must apply some standard of review to every issue it
considers * * * [so] no party has the power to control our
standard of review.” United States v. Vontsteen, 950 F.2d
1086, 1091 (5th Cir. 1992) (emphasis omitted).
                              23
     Said another way, standards of review are not claims that
parties can choose to make or not in a case. Those review
standards instead enforce structural judgments about the
relative expertise of trial and appellate courts, and the need
for efficiency, fairness, and stability in the judicial process.
See Puckett, 556 U.S. at 134. To illustrate, trial courts bear
primary responsibility for fact-finding because they see the
evidence and witnesses firsthand, and superintend evidentiary
rules and the creation of the record in the case. An appellate
court reviewing only the paper record is ill-positioned to
make factual findings, and so we review factual
determinations only for clear error. See Anderson v. City of
Bessemer City, N.C., 470 U.S. 564, 574 (1985); United States
v. United States Gypsum Co., 333 U.S. 364, 395 (1948). We
would not find facts de novo if a party failed to argue for—or
even agreed to waive—clear-error review.

     Plain-error review likewise enforces structural interests
by ensuring that (i) potential errors can be stopped before
harm occurs and resources are invested in a trial that must be
redone; (ii) trial court determinations are not ambushed on
appeal by never-before-voiced objections; and (iii) the
number of reversals is reduced, which promotes trust in the
stability of court judgments and finality in the enforcement of
criminal law. See Puckett, 556 U.S. at 134; see also United
States v. Hunter, 786 F.3d 1006, 1111 (D.C. Cir. 2015) (The
contemporaneous-objection rule’s goal of timely rectifying
errors “is not served when a defendant raises an objection
after proceedings are complete and a ruling has been handed
down.”).

    On top of that, the record shows that the government did
not forfeit its forfeiture argument. Before the Court of
Military Commission Review, the government specifically
argued that Bahlul “waived all motions, defenses or
                               24
objections (except for lack of jurisdiction or failure to allege
an offense) when he failed to raise any issues below.” Pet.
App. 161. Indeed, this court’s prior en banc decision
acknowledged that the government “argued for plain-error
review before the [Court of Military Commission Review], in
its original brief to the panel of this Court and in its brief to
the en banc court.” Bahlul I, 767 F.3d at 10 n.5; see also
Brief for the United States at 65, Bahlul v. United States, 2013
WL 297726 (D.C. Cir. Jan. 25, 2013) (arguing that Bahlul’s
Define and Punish Clause, Ex Post Facto Clause, and Article
III arguments “were forfeited below”).

     To be sure, at oral argument before the panel, the
government suggested that Bahlul’s structural argument might
not be forfeitable, see Pet. Supp. App. 234. But immediately
thereafter, counsel asserted that “[t]he structural component of
that argument is forfeitable,” id. at 235 (emphasis added). In
addition, the government argued that Bahlul had not raised an
Article III structural claim at all. See id. at 234 (“I do not
acknowledge that he was raising [a structural Article III
argument].”). In my view, that is far too murky a foundation
from which to launch this court into applying an unwarranted
standard of review to adjudge the constitutionality of a joint
exercise by the President and the Congress of their national
security and war powers. See, e.g., Youngstown Sheet & Tube
Co. v. Sawyer, 343 U.S. 579, 637 (1952) (Jackson, J.,
concurring) (joint exercises of power by the Political
Branches merit “the widest latitude of judicial
interpretation”); see also Bank Markazi v. Peterson, 136 S.
Ct. 1310, 1328 (2016) (“[F]oreign affairs” is “a domain in
which the controlling role of the political branches is both
necessary and proper.”); Center for National Security Studies
v. United States Dep’t of Justice, 331 F.3d 918, 927 (D.C. Cir.
2003) (“[T]he judiciary owes some measure of deference to
the executive in cases implicating national security[.]”).
                                25
     Nor do I understand why labeling Bahlul’s argument as
“structural” should change the rules. The Constitution at
every turn divides power not only horizontally between the
federal branches of government, but also vertically between
the national government, the States, and individuals. It is
hard to understand why Bahlul’s Article III claim is any more
structural than Bahlul’s Ex Post Facto claim, to which this
court sitting en banc accorded only plain-error review. See
also Carmell, 529 U.S. at 531 n.21 (Ex Post Facto Clause is
in part “aimed at * * * reinforcing the separation of powers”).

     The dissenting opinion adds that courts have a “strong
interest * * * in maintaining the constitutional plan of
separation of powers.” Joint Dissent at 9 (quoting Glidden
Co. v. Zdanok, 370 U.S. 530, 536 (1962)). True. But when
the only reason a separation-of-powers claim is not teed up is
because the defendant chose not to raise it below, courts
routinely apply plain-error review. See, e.g., United States v.
Gonzalez, 682 F.3d 201, 203 (2d Cir. 2012) (reviewing
separation-of-powers claim for plain error “because [the
defendant] did not raise the issue[] below”); United States v.
Anderson, 591 F.3d 789, 792 (5th Cir. 2009) (reviewing for
plain error where the defendant “could have mentioned
separation of powers [below] but, for whatever reason, he
chose not to”). 4

     The dissenting opinion also suggests that this really-
important-issue exception can be limited to intrusions on the
judiciary’s Article III turf because then the court is granting
de novo review for the courts’ “own benefit,” to “protect the

4
 See also, e.g., United States v. Clark, 634 F.3d 874, 877 (6th Cir.
2011); United States v. Carraway, 612 F.3d 642, 646 (7th Cir.
2010); United States v. Evans, 587 F.3d 667, 671 (5th Cir. 2009);
United States v. Rusan, 460 F.3d 989, 992 (8th Cir. 2006); United
States v. Pojilenko, 416 F.3d 243, 249 n.6 (3d Cir. 2005).
                               26
judiciary’s role within our system of divided government,”
Joint Dissent at 9, 6. But the Constitution separates power to
protect the rights and liberty of the people, not to protect the
courts for the courts’ sake. See New York v. United States,
505 U.S. 144, 182 (1992) (“T]he constitution divides
authority * * * for the protection of individuals. * * * The
Constitution’s division of power among the three branches is
violated where one branch invades the territory of another,
whether or not the encroached-upon branch approves the
encroachment.”). Plus it seems to me wholly untenable for
courts to decide that one criminal defendant’s Eighth
Amendment challenge to his death sentence fails on plain-
error review, see, e.g., United States v. McGarity, 669 F.3d
1218, 1255 (8th Cir. 2012), but an enemy combatant’s
challenge to his capital conviction succeeds because it was to
the court’s “own benefit” to afford it plenary review.
Whatever considerations may appropriately weigh in favor of
a discretionary decision to grant de novo review, the
dispositive factor in a criminal case should not be that the
federal judiciary decides it has skin in the game.

     Judge Kavanaugh’s concurring opinion concludes that
the “extraordinary importance” of the constitutional questions
is a reason to excuse Bahlul from the consequences of his
forfeiture and grant de novo review. Kavanaugh Concurring
Op. at 3 n.1. I think that gets the constitutional calculus
exactly backwards. The separation of powers should counsel
the greatest judicial hesitation when the Political Branches are
jointly exercising their judgment in areas of national security,
the conduct of war, and foreign relations. See generally
Youngstown Sheet & Tube Co., 343 U.S. at 636–637 (joint
actions of the Political Branches “personify the federal
sovereignty” and “would be supported by the strongest of
presumptions and the widest latitude of judicial
interpretation”). Here the constitutional structure itself raises
                                 27
a yellow caution flag against unnecessary judicial intrusion,
making it the better judicial course just to decide “the
narrower ground for adjudication of the constitutional
questions in [a] case * * * first.” Plaut, 514 U.S. at 217.
Here, that means applying plain-error review.

                                III

     To prevail on plain-error review, Bahlul must show that
the alleged error (i) is plain, (ii) affected his substantial rights,
and (iii) seriously affected the fairness, integrity or public
reputation of judicial proceedings. See Olano, 507 U.S. at
732–737. For an error to be “plain,” it must be “clear” or
“obvious.” Id. at 734. “A ruling’s error is clear if, at the time
it was made, a clear precedent in the Supreme Court or this
circuit established its erroneous character.” United States v.
Terrell, 696 F.3d 1257, 1260 (D.C. Cir. 2012).

     “Meeting all four prongs” of the plain-error test “is
difficult, as it should be.” Puckett, 556 U.S. at 135 (quotation
marks omitted). Doubly so here because the Supreme Court
has instructed that the actions of a military commission “are
not to be set aside by the courts without the clear conviction
that they are in conflict with the Constitution or laws of
Congress constitutionally enacted.” Quirin, 317 U.S. at 2.
Bahlul’s constitutional claims cannot survive that demanding
review. 5


5
  The Supreme Court explained in Hamdan v. Rumsfeld, 548 U.S.
557 (2006), that “the precedent” supporting trial by military
commission “must be plain and unambiguous” in those instances
“[w]hen * * * neither the elements of the offense nor the range of
permissible punishments is defined by statute or treaty,” id. at 602.
That standard does not apply here because the 2006 Act specifically
defines the elements of its conspiracy provision and identifies it as
                               28
     Bahlul’s principal argument is that, in authorizing his
prosecution before a military commission for what he labels
“inchoate conspiracy,” Congress exceeded its legislative
power under the Define and Punish Clause, U.S. CONST., Art.
I, § 8, cl. 10. Specifically, Bahlul argues that the conspiracy
for which he was charged and convicted cannot be an
“Offence[] against the Law of Nations,” within the meaning
of Article I of the Constitution, because inchoate conspiracy is
not a recognized crime under international law. Bahlul
further argues that inchoate conspiracy, as a stand-alone
offense, was traditionally triable by jury at common law and
for that reason falls exclusively within the Article III judicial
power.

     Because Bahlul presses only an as-applied challenge to
his own conviction under the 2006 Act, see Oral Arg. Tr. 6;
Pet. Br. 57, I would not decide whether Congress has the
constitutional power to authorize the prosecution generally of
inchoate conspiracies before a military commission. Rather,
for five reasons, it is neither clear nor obvious—in other
words, it is not plain—that the particular statutory conspiracy
of which Bahlul was convicted must be tried in an Article III
court.

     First, in arguing that Congress lacked the legislative
authority to assign his conspiracy charge to a military
commission for trial, Bahlul places great weight on the
government’s concession that inchoate conspiracy has not yet
been recognized as an offense against international law. Pet.
Br. 16; see Brief for the United States at 50, Bahlul v. United
States, 2013 WL 297726 (D.C. Cir. Jan. 25, 2013). But “we
are not obligated to accept the Government’s concession.”

an offense triable by military commission.           10 U.S.C.
§ 950v(b)(28).
                              29
Bahlul I, 757 F.3d at 18; see also United States v. Baldwin,
563 F.3d 490, 491 (D.C. Cir. 2009) (“We are not obligated to
accept the government’s confession of error, particularly
when there is reason to doubt whether the government’s
position is correct.”) (citation omitted). That is because “the
separation of powers does not depend on the views of
individual Presidents, nor on whether the encroached-upon
branch approves the encroachment.” Free Enterprise Fund v.
Public Company Accounting Oversight Bd., 561 U.S. 477,
497 (2010) (citation and quotation marks omitted). More to
the point, plain-error analysis looks at how clearly established
governing law is, not the briefing strategies of particular
parties.

    Second, Bahlul’s asserted error—Congress’s power to
criminalize traditional inchoate conspiracy in military
commission proceedings—is not in fact implicated by his
case. I agree with Judge Wilkins that the statutory conspiracy
of which Bahlul was convicted goes beyond the elements of
ordinary inchoate conspiracy. Traditionally, a conviction for
inchoate conspiracy requires proof of only two elements:
agreement between two or more persons, and intent thereby to
achieve a certain objective. Wayne R. LaFave, Substantive
Criminal Law § 12.2 (2015). Proof of neither an overt act nor
a completed offense is required. See United States v.
Shabani, 513 U.S. 10, 13–14 (1994) (“We have consistently
held that the common law understanding of conspiracy ‘does
not make the doing of any act other than the act of conspiring
a condition of liability.’”) (quoting Nash v. United States, 229
U.S. 373, 378 (1913)). Moreover, an inchoate conspiracy
could be tied to any object offense. Hogan v. O’Neill, 255
U.S. 52, 55 (1921).

   Conspiracy under the 2006 Act is materially different.
To begin with, in addition to requiring a specific intent to
                              30
commit the overt acts, the 2006 Act also requires that the
overt acts be committed with the intent “to effect the object of
the conspiracy.” 10 U.S.C. § 950v(b)(28); see Pet. Supp.
App. 137. Moreover, the only allowable objects of Bahlul’s
conspiracy are “substantive offenses triable by military
commission under” the Act. 10 U.S.C. § 950v(b)(28).
Bahlul does not dispute that those substantive offenses
include offenses against the law of war that may be tried
before a military commission. On top of that, the statutory
scheme seems to anticipate that a conviction will be linked to
a completed offense. That is because the statute specifically
ties the authorized sentences to the fate of the victims: the
crime “shall be punished, if death results to one or more of the
victims, by death or such other punishment as a military
commission under this chapter may direct, and, if death does
not result to any of the victims, by such punishment, other
than death, as a military commission under this chapter may
direct.” Id.

     In compliance with the statute, Bahlul was found to have
committed ten overt acts, including, for example, preparing a
recruiting video celebrating the USS Cole attack, acting as bin
Laden’s personal secretary, and preparing martyr wills for
two of the 9/11 hijackers. He was also found guilty of
conspiracy to commit seven charged objects, including
murder of protected persons, attacking civilians, murder in
violation of the law of war, and terrorism.

    Importantly, the military judge’s instructions to the
commission enforced those distinct features of statutory
conspiracy. The instructions expressly predicated Bahlul’s
conviction on a finding “beyond a reasonable doubt” that
Bahlul “personally committed at least one of the overt acts”
charged. Pet. Supp. App. 140–141. In addition, for each
object offense of the conspiracy, the commission was required
                              31
to “find beyond a reasonable doubt” that Bahlul (i) “entered
into an agreement” to commit the offense; (ii) did so
“intentionally”; (iii) “knew the unlawful purpose of the
agreement”; (iv) “joined with the intent to further its unlawful
purpose”; and (v) “committed an overt act in furtherance of
the agreement.” Id. at 145. The instructions emphasized that
the government must “prove[] beyond a reasonable doubt that
the agreement intended every element of” any offense that
was determined to be an object of the conspiracy. Id. at 140.

     Along with its guilty verdict, the commission returned
detailed factual findings documenting its determination that
Bahlul’s conspiracy met those statutory elements. The
commission found that Bahlul committed ten of the charged
overt acts, and entered into an agreement that “intended every
element” of all seven alleged object offenses, Pet. Supp. App.
140, including specifically “[m]urder of protected persons,”
“attacking civilians,” “murder in violation of the law of war,”
and “terrorism,” id. at 137, each of which violates Article 3 of
the Geneva Convention, see Geneva Convention (IV) Relative
to the Treatment of Prisoners of War art. 3, Aug. 12, 1949, 75
U.N.T.S. 2876 U.S.T. 3516.

     Thus, for all of Bahlul’s arguments about Congress’s
power to convict him by military commission of traditional or
common-law inchoate conspiracy, the commission convicted
him of a different and distinct statutory conspiracy offense, in
which Bahlul (i) knew the objects of the conspiracy, which
included multiple violations of the international law of war;
(ii) joined an agreement to intentionally further those
violations of the law of nations; (iii) personally intended to
have every element of those international law of war offenses
committed; and (iv) intentionally undertook the overt acts to
further the agreement’s unlawful purposes. Bahlul’s use of
the common law as a constitutional yardstick thus overlooks
                               32
the elements of the statutory offense of which he was actually
convicted and the dearth of precedent suggesting that
substantive offenses against the international law of war were
traditionally tried in courts at common law. Accordingly,
whatever the scope of congressional authority to consign
other stand-alone conspiracy offenses to a non-Article III
tribunal, it is not plain that conspiracy to commit international
war crimes as carefully defined in the 2006 Act falls
exclusively within the Article III judicial power.

     Third, given the specific elements of Bahlul’s conspiracy
conviction, any delta between his conspiracy offense and
those offenses that international law proscribes is too narrow
to rise to the level of plain constitutional error.

     To begin with, international law has recognized
conspiracy as a stand-alone offense for certain illegal acts that
bear a close resemblance to Bahlul’s charged conduct. For
example, international law has long allowed prosecution for
conspiracy to wage aggressive war (also known as common
plan to wage aggressive war). See 1 TRIAL OF THE MAJOR
WAR CRIMINALS BEFORE THE INTERNATIONAL MILITARY
TRIBUNAL: NUREMBERG, 14 November 1945–1 October
1946, p. 225 (1947). In that respect, international law
recognizes that “[p]lanning and preparation are essential to
the making of war,” and “[c]ontinued planning, with
aggressive war as the objective” may be punished as a
violation of the law of war. Id. at 224–225; see also Hamdan
v. Rumsfeld, 548 U.S. 557, 610 (2006) (plurality opinion)
(describing “common plan to wage aggressive war” as “a
crime against the peace [that] requires for its commission
actual participation in a ‘concrete plan to wage war’”)
(quoting 1 TRIAL OF MAJOR WAR CRIMINALS, supra, at 225).
                              33
     Like Bahlul’s conviction, conspiracy to commit
aggressive war at Nuremberg turned on the commission of
overt acts directly tied to waging aggressive war and an object
offense that was itself a crime against international law.
Nothing in constitutional text or settled precedent plainly
foreclosed Congress from bridging the gap between the
formal waging of such war by officials of Nazi Germany and
al Qaeda’s waging of terrorist aggression against the United
States.

     Modern statutes defining international law offenses also
permit punishment for conspiracy to commit genocide as a
stand-alone offense. See Updated Statute of the International
Criminal Tribunal for the Former Yugoslavia Art. 4 (2009)
(ICTY Statute); Statute of the International Tribunal for
Rwanda Art. 2 (1994); Convention on the Prevention and
Punishment of the Crime of Genocide Art. 3, Dec. 9, 1948, 78
U.N.T.S. 277. The Statute of the International Tribunal for
the Former Yugoslavia, for example, expressly recognizes
“conspiracy to commit genocide.” Id., Art. 4. The statute
defines genocide as, inter alia, “killing members of [a]
group,” “causing serious bodily or mental harm to members
of [a] group,” or “deliberately inflicting on the group
conditions of life calculated to bring about its physical
destruction in whole or in part,” “with intent to destroy, in
whole or in part, [that] national, ethnical, racial or religious
group[.]” Id., Art. 4(2)(a); see Simon v. Republic of Hungary,
812 F.3d 127, 143 (D.C. Cir. 2016) (similar, citing the
Convention on the Prevention of the Crime of Genocide).

    Of course, the object offenses tied to Bahlul’s conviction
do not include genocide. But Bahlul’s overt acts do include
attempts to kill and cause serious bodily and mental harm on
members of a specific group at least in part because of their
protected characteristics. Bahlul’s video celebrating the USS
                              34
Cole attack calls for jihad against the United States and
blames “Western infidels” for Muslim suffering. Bahlul I,
767 F.3d at 5–6. Bahlul’s video has been translated into
several languages and widely distributed. Id. at 6. Given that
international law proscribes a calculated conspiracy to
exterminate individuals on the basis of their nationality
(outside the context of formal war), constitutional law does
not plainly foreclose Congress from using its Define and
Punish Clause authority to outlaw a conspiracy to
intentionally commit mass murder of and to incite acts of
violence against Americans, at least when combined with an
overt act furthering an object offence that violates
international law.

     On top of that, international law recognizes some
conspiracy offenses as an independent source of criminal
liability. In particular, international law permits conviction
for joint criminal enterprise where “a plurality of persons
participat[es] in the criminal plan”; there is “a common
purpose which amounts to or involves the commission of a
crime”; and “the accused[] participat[es] in the common
design.” Guilia Bigi, Joint Criminal Enterprise in the
Jurisprudence of the International Criminal Tribunal for the
Former Yugoslavia and the Prosecution of Senior Political
and Military Leaders, in 14 MAX PLANCK YEARBOOK OF
UNITED NATIONS LAW 56 (2010). The Rome Statute, for
example, makes a person “criminally responsible and liable
for punishment for a crime” if that person “contributes to the
commission or attempted commission of such a crime by a
group of persons acting with a common purpose.” Rome
Statute of the International Criminal Court Art. 25(3)(d), July
17, 1998, 2187 U.N.T.S. 90. The contribution must be
“intentional,” and must be “made with the aim of furthering
the criminal activity or criminal purpose of the group” or “in
the knowledge of the intention of the group to commit the
                               35
crime.” Id. Given its settled roots in international law, there
is no dispute that Congress could authorize a military
commission prosecution for joint criminal enterprise. See
Oral Arg. Tr. 10.

     Classically, joint criminal enterprise differs from ordinary
inchoate conspiracy by its requirement of action in
furtherance of the agreement. See Allison Marston Danner &
Jenny S. Martinez, Guilty Associations: Joint Criminal
Enterprise, Command Responsibility, and the Development of
International Criminal Law, 93 CAL. L. REV. 75, 119 (2005).
The offense is also doctrinally distinct from traditional
conspiracy because it is a form of liability, while inchoate
conspiracy is a freestanding substantive crime. Id. at 119; see
also Hamdan, 548 U.S. at 610 n.40 (plurality opinion)
(“[J]oint criminal enterprise” is a “species of liability for the
substantive offense (akin to aiding and abetting), not a crime
on its own.”).

     But as applied to this case, the distinctions between a
conspiracy conviction under the 2006 Act and what a
conviction for joint criminal enterprise would have entailed
are narrower than they would be for traditional inchoate
conspiracy. Bahlul’s conspiracy charge under the 2006 Act
did require explicit proof of an overt act and involved a
completed object offense. As a result, “it is not clear whether
th[e] formal distinction between [joint criminal enterprise]
and conspiracy carries much practical weight.” Danner &
Martinez, supra, at 119; see Peter Margulies, Defining,
Punishing and Membership in the Community of Nations, 36
FORDHAM INT’L L.J. 1, 86 (2013) (The “pairing of joint
intention with action [in the Rome Statute’s codification of
Joint Criminal Enterprise] is very close to conspiracy—close
enough that no individual charged with the latter as a mode of
liability can claim lack of notice.”). Whatever the distinctions
                               36
between the two, they do not make a clear or plain
constitutional difference.

     Beyond that, Bahlul conceded at oral argument, Oral Arg.
Tr. 9–10, that the Constitution would permit his trial before a
military commission on a Pinkerton conspiracy theory of
liability, see Pinkerton v. United States, 328 U.S. 640 (1946).
The Pinkerton doctrine of conspiracy holds an individual
vicariously liable for reasonably foreseeable substantive
crimes committed by his co-conspirators in furtherance of the
conspiracy. See id. at 646–647.

     Pinkerton “intertwines conspiracy as a substantive crime
with conspiracy as a theory of liability[.]” Danner &
Martinez, supra, at 116; see, e.g., United States v. Edmond,
924 F.2d 261, 268 (D.C. Cir. 1991) (Pinkerton established
that commission of a substantive offense and conspiracy to
commit it are distinct crimes, and simultaneously authorized
holding a conspirator responsible for substantive criminal acts
committed by a co-conspirator). But Pinkerton liability is
distinct from inchoate conspiracy because it relies on the
imputation of co-conspirators’ completed offenses, and
requires a finding that they were “reasonably foresee[able] as
a necessary or natural consequence of the unlawful
agreement.” Pinkerton, 328 U.S. at 648; see also Danner &
Martinez, supra, at 115–116. In Bahlul’s case, because he
joined agreements to intentionally commit war crimes, acted
in furtherance of those agreements, and was intricately
involved in preparing two 9/11 perpetrators for their attacks, it
is far from plain that the acts of terrorism that flowed directly
from his conspiratorial activities were not precisely what he
intended to have happen, let alone “reasonably foresee[able]
as a necessary or natural consequence of the unlawful
agreement.” Pinkerton, 328 U.S. at 648. At least the gap
                              37
between the two forms of conspiracy is not so clear as to tie
Congress’s legislative hands on plain-error review.

     Bahlul’s position—essentially adopted by the dissenters,
see Joint Dissent at 52–60—is that, although a hypothetical
conviction for common plan to wage aggressive war, joint
criminal enterprise, or Pinkerton conspiracy would have been
valid, his conviction here was unconstitutional because the
2006 Act outlaws a stand-alone “conspiracy.” Oral Arg. Tr.
9–10. But there is no dispute that the law of nations permits
some freestanding conspiracy convictions—for aggressive
war and genocide. So the fact that the 2006 Act denominates
a stand-alone conspiracy offense cannot make all the
difference.

    If Bahlul means by this argument that the 2006 Act might
allow someone else to be convicted of ordinary, common-
law-like conspiracy, that is not his argument to make.
Outside the First Amendment context (which is not plausibly
implicated here), a criminal defendant whose culpable
conduct falls within the constitutional range cannot upend that
conviction just because the statute’s alleged overbreadth
might permit the unconstitutional conviction of another
individual. See United States v. Williams, 553 U.S. 285, 304
(2008) (“[O]rdinarily ‘a plaintiff who engages in some
conduct that is clearly proscribed cannot complain of the
vagueness of the law as applied to the conduct of others.’”)
(quoting Hoffman Estates v. Flipside, Hoffman Estates, Inc.,
455 U.S. 489, 495 (1982)) (alteration omitted).

     What matters here is that Bahlul’s own conviction was
not for ordinary inchoate conspiracy. It was for a carefully
crafted form of statutory conspiracy that, on the record of this
case, resembles in important ways those forms of conspiracy
or collective action that get the international-law nod of
                              38
approval. Surely plain-error review cannot turn on the same
nuances of varying conspiracy-liability theories that confound
most first-year law students. See Terrell, 696 F.3d at 1260
(requiring on-point precedent in the Supreme Court or this
circuit to establish clear error).

     Contrary to the worry expressed in the dissenting opinion
(at 55–60), that conclusion does not find Bahlul guilty of a
crime for which he was not charged or convicted. Instead, I
decide only that, given the elements of the statutory crime of
which Bahlul was convicted and its comparability in some
key respects to conspiracies that the parties agree transgress
international law, Bahlul’s conviction of conspiracy under the
2006 Act did not plainly exceed Congress’s constitutional
authority.

     Fourth, Supreme Court precedent has not required
slavish adherence to the precise contours of explicitly
recognized international law as a precondition to Congress’s
exercise of its power under the Define and Punish Clause.
For instance, in United States v. Arjona, 120 U.S. 479 (1887),
the Court held that the Define and Punish Clause gave
Congress the authority to punish an individual who
counterfeited another nation’s securities, id. at 487–488. The
Court did not identify any express international proscription
on counterfeiting securities, but explained that the prohibition
on counterfeiting money might, “with just propriety, be
extended to the protection of this more recent custom among
bankers of dealing in foreign securities[.]” Id. at 486. For
that reason, the Supreme Court concluded, “a law which is
necessary and proper to afford this protection” fell within
Congress’s Article I power because the law was “needed to
carry into execution a power conferred by the constitution on
the government of the United States exclusively.” Id.
                              39
    Arjona thus held that Congress’s power to criminalize an
offense did not turn on whether the act was expressly
prohibited by international law. Instead, it was sufficient that
proscribing certain conduct was “necessary and proper” to
protect rights implicitly recognized by the law of nations.

     Likewise, in In re Yamashita, 327 U.S. 1 (1946), the
Supreme Court affirmed the conviction of a Japanese military
commander before a military commission for “permitting [his
troops] to commit brutal atrocities and other high crimes
against people of the United States and of its allies and
dependencies,” id. at 13–14. Even though international law
had not expressly recognized liability for such supervisorial
conduct, the Court noted that international law outlined the
commander’s duty to uphold the law of war. See id. at 15–16
(Geneva Conventions imposed on the commander an
affirmative “duty * * * to provide for the details of execution
of the foregoing articles (of the convention)”); cf. id. at 40
(Murphy, J., dissenting) (protesting that Yamashita’s
conviction was not “based upon charges fairly drawn in light
of established rules of international law and recognized
concepts of justice”). What proved critical in Yamashita was
that the commander’s offense—the failure to restrain
subordinate troops—“would almost certainly result in
violations which it is the purpose of the law of war to
prevent.” Id. at 15 (majority opinion).

     So too here. Bahlul’s statutory conspiracy conviction and
the commission’s factual determinations on which it rested
are closely tied to offenses against the “Law of Nations”
within the meaning of the Constitution’s Define and Punish
Clause, Art. I, § 8, cl. 10. At a bare minimum, plain-error
review does not leave Congress powerless to do nothing more
than mimic the precise contours of extant international
precedent.
                               40
     Fifth and finally, plain-error review requires Bahlul to
identify “clear precedent” from this court or the Supreme
Court “establish[ing] [the] erroneous character” of his
conspiracy conviction, Terrell, 696 F.3d at 1260. But the
closest precedent from this court is our prior en banc decision
in Bahlul I, which points in the opposite direction. There, a
majority of this court held that it is not “plain” that conspiracy
falls outside the statutory limits on crimes triable by military
commission. 767 F.3d at 22. Because the Ex Post Facto
Clause, U.S. CONST., Art. I, § 9, cl. 3, forbade reliance on the
2006 Act, the court had to determine whether Bahlul’s
inchoate conspiracy conviction fell plainly outside the “law of
war” within the meaning of the Articles of War, 10 U.S.C.
§ 821. See Bahlul I, 767 F.3d at 22. Under the Articles of
War, conspiracy had to be an offense that “by the law of war
may be tried by military commissions.” 10 U.S.C. § 821.

     As this court explained in Bahlul I, the Supreme Court
has not yet resolved the question whether “law of war” means
only the international law of war or includes “the common
law of war developed in U.S. military tribunals.” 767 F.3d at
22–23. But on plain-error review, it was sufficient that the
Supreme Court has relied on domestic precedent in addition
to international law to ascertain whether a crime is triable as
an offense against the “law of war.” Id. at 23–24 (citing
Hamdan, 548 U.S. at 603–609 (plurality opinion); id. at 689–
704 (Thomas, J., dissenting); Quirin, 317 U.S. at 31–35, 42
n.14; Yamashita, 327 U.S. at 19–20).

    So too here, three examples of domestic wartime
precedent make it far from plain that conspiracy under the
2006 Act would not be triable by military commission.

    For starters, the individuals held responsible for President
Lincoln’s assassination were charged with and convicted of
                              41
“combining, confederating, and conspiring together * * * to
kill and murder, within the Military Department of
Washington, and within the fortified and intrenched lines
thereof, Abraham Lincoln[.]” H.R. Doc. No. 314, 55th Cong.,
3d Sess., 696 (1899). President Andrew Johnson personally
approved the convictions, relying in part on the opinion of
Attorney General James Speed advising that the individuals
could be tried for conspiracy before a military commission.
11 Op. Att’y Gen. at 297. As this court explained in Bahlul I,
“this highest-level Executive Branch deliberation is worthy of
respect in construing the law of war.” 767 F.3d at 25 (citing
Sosa v. Alvarez-Machain, 542 U.S. 692, 733–734 (2004)).

     In addition, Nazi saboteurs who entered the United States
intending to destroy industrial facilities were convicted of
conspiracy in Quirin and in Colepaugh v. Looney, 235 F.2d
429, 431–432 (10th Cir. 1956). While the Supreme Court and
the Tenth Circuit each affirmed the saboteurs’ convictions
based on other charges, those decisions are “prominent
example[s]” of conspiracy charges reached in law-of-war
military commissions, approved by the executive, and
permitted by the judiciary, including the Supreme Court.
Bahlul I, 767 F.3d at 26.

    Lastly, during the Korean War, General Douglas
MacArthur ordered that persons accused of “conspiracies and
agreements to commit * * * violations of the laws and
customs of war of general application” be tried by military
commission.    Letter Order, Gen. HQ, United Nations
Command, Tokyo, Japan, Trial of Accused War Criminals
(Oct. 28, 1950) (Rules of Criminal Procedure for Military
Commissions, Rule 4).

    While not definitively answering the ultimate
constitutional question, “the historical practice of our wartime
                               42
tribunals is sufficient to make it not ‘obvious’ that conspiracy
was not traditionally triable by [a] law-of-war military
commission” under the Articles of War as an offense against
the law of war. Bahlul I, 767 F.3d at 27 (citing Olano, 507
U.S. at 734). Further, because the “law of war” in the Articles
of War “incorporate[s] by reference, as within the jurisdiction
of military commissions, all offenses which may
constitutionally be included within that jurisdiction,” Quirin,
317 U.S. at 30, those same domestic precedents underscore
the absence of any plain constitutional error in Bahlul’s
statutory conspiracy conviction by a military commission.

                               IV

    Bahlul’s other constitutional challenges also cannot
surmount plain-error review.

      First, he argues that his conspiracy conviction runs afoul
of the Constitution’s Judicial Power Clause, Art. III, § 2, cl. 1.
But precedent has long established that criminal prosecutions
for violations of the law of war do not fall within the
exclusive jurisdiction of Article III courts. See, e.g., Johnson
v. Eisentrager, 339 U.S. 763, 786 (1950) (lawfulness of
military commission jurisdiction is “well-established”);
Bahlul II, 792 F.3d at 7 (citing Quirin, 317 U.S. at 46).
Bahlul’s argument that his statutory conspiracy conviction
falls beyond the law of nations amounts to nothing more than
a repackaging of his Define and Punish Clause argument.
The error—if any—is just as far from plain under Article III
as it is under Article I.

     Second, Bahlul contends that his conviction violated his
right to a trial by jury. Bahlul is correct that Article III,
Section 2, Clause 3 of the Constitution provides that “[t]he
Trial of all Crimes, except in Cases of Impeachment, shall be
                              43
by Jury.”   But if any error occurred, it was not plain or
obvious.

     To begin with, no established precedent even extends the
jury trial right to non-citizens being held outside the United
States’ sovereign territory. In Boumediene v. Bush, 553 U.S.
723 (2008), the Supreme Court for the first time extended
constitutional protection to an alien at Guantanamo Bay, id. at
795. That holding, however, was “explicitly confined * * *
‘only’ to the extraterritorial reach of the Suspension Clause,”
and expressly “disclaimed any intention to disturb existing
law governing the extraterritorial reach of any constitutional
provisions, other than the Suspension Clause.” Rasul v.
Myers, 563 F.3d 527, 529 (D.C. Cir. 2009) (quoting
Boumediene, 553 U.S. at 795). And it is settled that certain
other constitutional provisions do not protect aliens outside
the sovereign United States. See, e.g., United States v.
Verdugo-Urquidez, 494 U.S. 259, 261 (1990) (the Fourth
Amendment does not apply to the search and seizure of
property owned by a nonresident alien and located abroad);
Kiyemba v. Obama, 555 F.3d 1022, 1026 & n.9 (D.C. Cir.
2009) (Due Process Clause of Fifth Amendment does not
apply to aliens at Guantanamo), vacated, 559 U.S. 131 (2010)
(per curiam), reinstated on remand, 605 F.3d 1046 (D.C. Cir.
2010) (per curiam), cert. denied, 563 U.S. 954 (2011).

     If anything, precedent undermines Bahlul’s claim. In
Quirin, the Supreme Court held that Nazi saboteurs had no
right to trial by jury, explaining that “trial by a jury of the
vicinage where the crime was committed” was a “procedure[]
unknown to military tribunals, which are not courts in the
sense of the Judiciary Article.” 317 U.S. at 39. Article III’s
Jury Trial Clause, the Supreme Court elaborated, “preserve[d]
unimpaired trial by jury in all those cases in which it had been
recognized by the common law.” Id. But it did not go so far
                              44
as “to have extended the right to demand a jury to trials by
military commission, or to have required that offenses against
the law of war not triable by jury at common law be tried only
in the civil courts.” Id. at 40.

     Bahlul contends that, under Quirin, the jury-trial right
hinges on whether a charge was triable by jury at common
law, not whether the charge was also properly tried before the
military commission. Pet. Br. 27; Oral Arg. Tr. 15–16. The
sabotage charge in Quirin did not entail a jury trial right at
common law, but conspiracy did. See Callan v. Wilson, 127
U.S. 540, 549 (1888).

     Subsequent precedent indicates otherwise. See Whelchel
v. McDonald, 340 U.S. 122, 127 (1950) (“The right to trial by
jury guaranteed by the Sixth Amendment is not applicable to
trials by courts-martial or military commission.”); Sanford v.
United States, 586 F.3d 28, 35 (D.C. Cir. 2009) (“[T]he Sixth
Amendment right to a criminal jury trial does not, itself, apply
to the military.”); cf. Granfinanciera S.A. v. Nordberg, 492
U.S. 33, 53 (1989) (“[I]f Congress may assign the
adjudication of a statutory cause of action to a non-Article III
tribunal, then the Seventh Amendment poses no independent
bar to the adjudication of that action by a nonjury
factfinder.”). There accordingly is nothing plain or obvious
about Bahlul’s entitlement to a trial by jury.

      Third, Bahlul argues that the First Amendment’s free
speech guarantee forecloses a conviction for his political
speech, namely the al Qaeda recruitment video he created
about the terrorist attack on the USS Cole. Pet. Br. 38, 40,
Bahlul II, 2014 WL 3962849. As with Bahlul’s claimed jury-
trial right, no governing precedent extends First Amendment
protection to speech undertaken by non-citizens on foreign
soil, so no plain error occurred.
                              45
     What is settled, moreover, is that the First Amendment
offers no shield to speech like Bahlul’s that is “directed to
inciting or producing imminent lawless action and * * * [is]
likely to incite or produce such action.”          Holder v.
Humanitarian Law Project, 561 U.S. 1, 43–44 (2010)
(alterations omitted; quoting Brandenburg v. Ohio, 395 U.S.
444, 447 (1969) (per curiam)); see also Bahlul, 820
F. Supp. 2d at 1249 (Bahlul’s USS Cole recruitment video
was “aimed at inciting viewers to join al Qaeda, to kill
Americans, and to cause destruction.”).

     Fourth, Bahlul argues that the 2006 Act violates the Fifth
Amendment’s guarantee of equal protection because it
authorized trials before a military commission for alien enemy
combatants, but not for enemy combatants who are U.S.
citizens. The short answer is that no relevant precedent
plainly or clearly supports the application of equal protection
principles in this law-of-war context to foreign enemy
combatants.

                              V

     In sum, I would review Bahlul’s constitutional challenges
only for plain error. Under that standard, I would hold that
his conviction for conspiracy under the 2006 Act by a law-of-
war military commission did not plainly exceed Congress’s
power under Article I’s Define and Punish Clause or trench
upon Article III’s assignment of the judicial power to federal
courts. Nor did his conviction violate any of the other
constitutional protections Bahlul invokes. I accordingly
concur in the judgment affirming Bahlul’s conviction.
     WILKINS, Circuit Judge, concurring: I agree with much of
the reasoning in section III of Judge Millett’s opinion, but my
view of this case differs in two ways. First, I do not believe a
plain error standard applies. For the reasons set forth in the
2015 panel opinion, Bahlul cannot forfeit his structural
Article III claim. See Al Bahlul v. United States, 792 F.3d 1,
3-7 (D.C. Cir. 2015), vacated by order granting rehearing en
banc, Al Bahlul v. United States, No. 11-1324 (D.C. Cir. Sept.
25, 2015); see also Commodity Futures Trading Comm’n v.
Schor, 478 U.S. 833, 850-51 (1986). “Every extension of
military jurisdiction is an encroachment on the jurisdiction of
the civil courts,” Bahlul, 792 F.3d at 5 (quoting Reid v.
Covert, 354 U.S. 1, 21 (1957) (plurality)), meaning Bahlul’s
challenge “goes to the heart of the judiciary’s status as a
coordinate branch of government,” id. at 6. Whether his
conspiracy conviction falls within the Article III exception for
law-of-war military commissions should be a question for de
novo review.

     The second reason I write separately is because there is
no constitutional violation under a de novo standard.
“Embedded in the traditional rules governing constitutional
adjudication is the principle that a person to whom a statute
may constitutionally be applied will not be heard to challenge
that statute on the ground that it may conceivably be applied
unconstitutionally to others, in other situations not before the
Court.” Broadrick v. Oklahoma, 413 U.S. 601, 610 (1973);
see also New York v. Ferber, 458 U.S. 747, 767 (1982).
Accordingly, to review Bahlul’s claim, we must test the
premise of his contention as applied to him. His particular
conviction is far from one for ordinary, inchoate conspiracy.
An examination of the record shows Bahlul was really
convicted of an offense tantamount to substantive war crimes
under a Pinkterton theory of liability. It is not that “any delta
between his conspiracy offense and those offenses that
international law proscribes is too narrow to rise to the level
of plain constitutional error.” Millett Op. 32. There is no
                               2
delta. The government proved beyond a reasonable doubt that
Bahlul knowingly took part in al-Qaeda’s plan on September
11, 2001 to murder American civilians. His statutory
conspiracy conviction does not violate international law,
which recognizes what is essentially Pinkerton liability, and it
therefore comports with Article III. See Bahlul, 792 F.3d at
22 (“The international law of war limits Congress's authority
because the Constitution expressly ties that authority to ‘the
Law of Nations.’”) (quoting U.S. CONST. art. I, § 8, cl. 10).

                               I.

     Bahlul attacks his conviction for conspiracy under
Section 950v(b)(28) of the 2006 Military Commission Act
(“2006 MCA”), Pub. L. No. 109-366, 120 Stat. 2600. He
alleges that the MCA conspiracy crime violates Article III
because the prosecution of inchoate conspiracy violates
international law. In other words, Bahlul mounts a facial
challenge to the statute, and in so doing assumes that his
conviction in fact implicates inchoate conspiracy. But we
cannot take Bahlul at his word. Instead, we must scrutinize
the statute, and then examine the specific facts of his
conviction to see whether it actually bears on the
constitutional principle asserted. See United States v. Stevens,
559 U.S. 460, 474 (2010); Vill. of Hoffman Estates v.
Flipside, Hoffman Estates, Inc., 455 U.S. 489, 494-95 (1982).
In line with decades of express Supreme Court instruction in
this regard, we must treat this case as an as-applied challenge.
And when we ask ourselves whether Bahlul was really
prosecuted for inchoate conspiracy, the answer is clearly no.

     This framework of examining Bahlul’s constitutional
challenge to his MCA conviction “[b]y focusing on the
factual situation before us” is long-accepted practice. Ferber,
458 U.S. at 768; see also Sabri v. United States, 541 U.S. 600,
                                  3
609 (2004); Chapman v. United States, 500 U.S. 453, 467
(1991); Bd. of Trustees of State Univ. of N.Y. v. Fox, 492 U.S.
469, 484-85 (1989); N.Y. State Club Ass’n, Inc. v. City of
N.Y., 487 U.S. 1, 11 (1988); Vill. of Hoffman Estates, 455
U.S. at 495 n.7; United States v. Mazurie, 419 U.S. 544, 550
(1975); Broadrick, 413 U.S. at 610; United States v. Powell,
423 U.S. 87, 92 (1975).

     It is by now a maxim that a facial attack on a criminal
statute simply cannot prevail where the law is constitutional
as applied to a defendant’s own conduct. See Schall v.
Martin, 467 U.S. 253, 268 n.18 (1984) (“[O]utside the limited
First Amendment context, a criminal statute may not be
attacked as overbroad.”) (citing Ferber, 458 U.S. 747); see
also Holder v. Humanitarian Law Project, 561 U.S. 1, 20
(2010) (“[A] plaintiff who engages in some conduct that is
clearly proscribed cannot complain of the vagueness of the
law as applied to the conduct of others.”) (citing Vill. of
Hoffman Estates, 455 U.S. at 495). The Supreme Court has
often cautioned that “[f]acial challenges of this sort are
especially to be discouraged,” Sabri, 541 U.S. at 609, and
“[t]he fact that [a criminal statute] might operate
unconstitutionally under some conceivable set of
circumstances is insufficient to render it wholly invalid.” 1

1
   There is some controversy in recent years about whether the
Salerno standard universally applies. See Hodge v. Talkin, 799
F.3d 1145, 1156 (D.C. Cir. 2015) (“[T]he Court has also indicated
that the standard for facial invalidity may be less stringent in some
situations, instead turning on whether the statute lacks any ‘plainly
legitimate sweep.’” (quoting Wash. State Grange v. Wash. State
Republican Party, 552 U.S. 442, 449 (2008))). At the very least,
“all agree that a facial challenge must fail where the statute has a
plainly legitimate sweep,” id. at 450 (internal quotations marks
omitted), a standard Bahlul’s conviction necessarily survives given
that the facts of his own case do not violate Article III. See also id.
                                 4
United States v. Salerno, 481 U.S. 739, 745 (1987). “Indeed,
this is why facial constitutional challenges [have been] . . .
unsuccessful as defenses to criminal prosecutions for non-
expressive conduct.” 2 Coleman v. DeWitt, 282 F.3d 908, 914
n.3 (6th Cir. 2002).

     While Bahlul attempts to deflect attention from his own
circumstances by erecting a straw man, it is not our job to
answer the abstract question of whether prosecuting inchoate
conspiracy violates our separation of powers – we do not even
examine whether the elements of Section 950v(b)(28)
generally equate to a prosecution for inchoate conspiracy.
Rather, we examine whether the acts committed and proven in
the course of this specific prosecution really equate with
inchoate conspiracy. This jurisprudential approach does not
“violate basic principles of criminal justice,” as the dissent
urges. See Dissenting Op. at 53. We employ it not just with
regard to criminal statutes, but throughout constitutional
adjudication, including in the Article III context. We treat a
facial separation of powers challenge “as if it were an as-
applied challenge,” and reject it where the particular
application of the statute at issue was constitutional. U.S. ex
rel. Schweizer v. Oce N.V., 677 F.3d 1228, 1235 & n.7 (D.C.
Cir. 2012) (citing Texas v. Johnson, 491 U.S. 397, 403 n.3
(1989)); see also Free Enter. Fund v. Pub. Co. Accounting
Oversight Bd., 537 F.3d 667, 670 (D.C. Cir. 2008) (“To
succeed in its facial challenge to Title I of the Act under the

(“[W]e must be careful not to go beyond the statute’s facial
requirements and speculate about ‘hypothetical’ or ‘imaginary’
cases.”).
2
  As Judge Millett’s opinion points out, the First Amendment
context is not implicated here by Bahlul’s Article III challenge. See
Millett Op. 37.
                                  5
Appointments Clause and separation of powers, the Fund
bears a heavy burden to show that the provisions of which it
complains are unduly severe in all circumstances and cannot
be constitutionally applied.”) (footnote omitted), aff’d in part,
rev’d in part and remanded, 561 U.S. 477 (2010).

     Evaluated in this way, Bahlul’s facial challenge must fail
because his own conviction does not violate Article III. See
infra Part III. He was not convicted of inchoate conspiracy.
It does not matter that Bahlul framed his argument as a facial
attack; an appellant cannot change our approach to deciding
constitutional issues “by concession, inadvertence, poor oral
advocacy or otherwise.” 3 Millett Op. 22 (quoting Bahlul, 792
F.3d at 32 n.3 (Henderson, J., dissenting)). Waiver and
forfeiture rules have no application in this regard. Nor are
there any “serious due process concerns” raised by this
approach to Bahlul’s collateral attack, brought at the eleventh
hour following a trial during which he presented no defense,
and after he admitted to all but one of the factual allegations
against him. Dissenting Op. at 61. It would be particularly
ill-advised to ignore the “usual judicial practice” of deciding
the as-applied question before proceeding to a facial
challenge, Fox, 492 U.S. at 484, given that “[s]triking down
an Act of Congress ‘is the gravest and most delicate duty that
this Court is called on to perform.’” Shelby Cty. v. Holder,
133 S. Ct. 2612, 2631 (2013) (quoting Blodgett v. Holden,
275 U.S. 142, 148 (1927) (Holmes, J., concurring)). This
“delicate power of pronouncing an Act of Congress
unconstitutional is not to be exercised with reference to

3
  For this same reason, the Court did not consider itself restricted to
Citizens United’s exact framing of its challenge on appeal. Citizens
United v. Fed. Election Comm’n, 558 U.S. 310, 331 (2010) (“The
parties cannot enter into a stipulation that prevents the Court from
considering certain remedies if those remedies are necessary to
resolve a claim that has been preserved.”).
                               6
hypothetical cases thus imagined.” United States v. Raines,
362 U.S. 17, 22 (1960). But that is what we would be doing if
we allowed ourselves to be hurled headlong into the structural
Article III claim served up by Bahlul, despite the fact that the
record of his conviction raises no such constitutional concern.

     While the separation of powers question potentially
implicated by this case is a critical one, it is not actually
implicated by the facts before us. If it were, I would be
inclined to agree with the dissent. However, I cannot join that
opinion today on account of the specifics of Bahlul’s
conviction, which, for the following reasons, shows he was
not convicted of inchoate conspiracy.

                              II.

     There are several features of inchoate conspiracy that
make it the “darling of the modern prosecutor’s nursery.”
Harrison v. United States, 7 F.2d 259, 263 (2d Cir. 1925). At
its “essence,” conspiracy is “an agreement to commit an
unlawful act.” Iannelli v. United States, 420 U.S. 770, 777
(1975). The agreement is the prohibited actus reus. 2
WAYNE R. LAFAVE, SUBSTANTIVE CRIMINAL LAW § 12.2(a)
(2d ed. 2003). It is not necessary that the parties to the
conspiracy actually succeed in committing the crime. See
United States v. Jimenez Recio, 537 U.S. 270, 274 (2003).
Many jurisdictions require an overt act in furtherance of the
conspiracy, but the overt act itself does not have to be
unlawful. LAFAVE § 12.2(b). The government often proves
the existence of the agreement through circumstantial
evidence, id. § 12.2(a), and does not need to show express
agreement to the plan’s every detail, see Blumenthal v.
United States, 332 U.S. 539, 557 (1947). Impossibility is not
a defense, the merger rule does not apply, and withdrawal
from the conspiracy is difficult, requiring an affirmative step.
                              7
See Neal Katyal, Conspiracy Theory, 112 YALE L.J. 1307,
1309 (2003).

     Conspiracy’s detractors therefore disapprove of it as a
vague, “elastic, sprawling and pervasive offense.” Krulewitch
v. United States, 336 U.S. 440, 445 (1949) (Jackson, J.,
concurring). At the same time, outlawing conspiracy is
important to prevent crimes before they are actually
committed. See LAFAVE § 12.1(c); see also Katyal, supra, at
1313 (“[W]ith giving prosecutors more tools for leverage over
conspirators comes the possibility of . . . preventing some
crime before it happens.”). We punish inchoate crimes
precisely because they constitute “[a] step toward the
commission of another crime, the step in itself being serious
enough to merit punishment.” Inchoate Offense, BLACK'S
LAW DICTIONARY (10th ed. 2014). Put another way, waiting
for the crime to be completed needlessly puts people at risk.
See Br. of Amici Curiae Former Gov’t Officials et al. 15
[hereinafter Former Gov’t Officials].          Conspiracy is
particularly advantageous in this regard because the crime is
complete at the moment of agreement; unlike an attempt
crime, it can be punished even before a substantial step
towards the offense is taken. See LAFAVE § 12.1(c).

     Importantly, conspiracy is at once a stand-alone crime,
and also a theory of liability. As a stand-alone crime against
the United States, for example, conspiracy requires several
things. See 18 U.S.C. § 371. There must be an agreement by
two or more persons to commit an offense. The defendant
must deliberately join the conspiracy with knowledge of this
purpose. And, one of the conspiracy members must, at some
time during its existence, perform an overt act to further or
advance the purpose of the agreement. See id.; United States
v. Treadwell, 760 F.2d 327, 333 (D.C. Cir. 1985); see also 2
                               8
KEVIN F. O’MALLEY ET AL., FEDERAL JURY PRACTICE &
INSTRUCTIONS § 31:03 (6th ed. 2008) [hereinafter FED. JURY].

     Alternatively, as a form of vicarious liability – so-called
Pinkerton liability – a member to a conspiracy can be held
liable for reasonably foreseeable offenses committed by
others in the group. See Pinkerton v. United States, 328 U.S.
640, 646-47 (1946) (“And so long as the partnership in crime
continues, the partners act for each other in carrying it
forward”).     Under a Pinkerton theory, a defendant’s
responsibility for the underlying offense generally requires
that the substantive offense be reasonably foreseeable and
committed in furtherance of the conspiracy’s objectives, all
while the defendant was a member of the conspiracy. See
United States v. Washington, 106 F.3d 983, 1011 (D.C. Cir.
1997); FED. JURY § 31:10.

     Bahlul argues that conspiracy is “dangerously broad in its
sweep when used to punish the enemy in war.” Pet’r Br. 24.
He and Amici essentially warn that all the so-called evils of
inchoate conspiracy – that it is easy to charge, overbroad, and
difficult to defend – are amplified when the offense is tried by
a law-of-war military commission, as opposed to an Article
III court. See Pet’r Br. 29, 33-34; Br. of Amici Curiae Int’l
Law Scholars 16-19. That may be true, but for the reasons
that follow, Bahlul’s conviction shares little in common with
the above-described features of inchoate conspiracy, and
instead bears a close kinship to a conviction under a Pinkerton
theory, which does not offend the Constitution.

                              III.

     The 2006 MCA contained important limitations on
military commission authority that distinguish this
prosecution from that of ordinary, vanilla conspiracy. As
                               9
Judge Millett’s opinion points out, there is a real question as
to whether the conspiracy offense codified by the MCA
amounts to inchoate conspiracy. See Millett Op. 29-30.
Significantly, the statute specifically references victims,
containing two sentencing variations depending on whether
anybody dies as a result of the conspiracy. 10 U.S.C.
§ 950v(b)(28) (2006). In other words, by conditioning
punishment on either death or other harm befalling another
person, the MCA’s version of conspiracy contemplates the
completion of a substantive offense. That is a far cry from
inchoate conspiracy, which is achieved “even though the
substantive offence is not successfully consummated.”
Inchoate, BLACK’S LAW DICTIONARY (10th ed. 2014)
(quoting Andrew Ashworth, PRINCIPLES OF CRIMINAL LAW
395 (1991)). Bahlul does not ask us to decide if the MCA’s
version of conspiracy always requires a completed offense,
but in this case there is one: the September 11th attacks.

     Consider next that in a typical prosecution for inchoate
conspiracy, the government need only prove that someone
who was a member of the conspiracy committed the requisite
overt act. Pinkerton, 328 U.S. at 646-47 (“It is settled that ‘an
overt act of one partner may be the act of all without any new
agreement specifically directed to that act.’”) (quoting United
States v. Kissel, 218 U.S. 601, 608 (1910)); FED. JURY
§ 31:07. Accordingly, ordinary conspiracy jury instructions
say that the acts of co-conspirators can be considered proof of
the conspiracy charge against the defendant. FED. JURY
§ 31:06. No similar instruction was given in Bahlul’s trial.
By contrast, the MCA’s version of conspiracy requires, and
the commission was instructed that it must find, that Bahlul
committed an overt act himself. See 10 U.S.C. § 950v(b)(28);
Trial Tr. 846 (directing that the panel find Bahlul “knowingly
committed at least one of the following overt acts for the
                              10
purpose of bringing about one of the objects of the
agreement.”).

     Not only does the MCA’s statutory conspiracy require a
victim and a defendant’s own overt act, but what was proven
at Bahlul’s trial also goes far beyond conspiracy’s traditional
requirements. The commission’s special verdict form and ten
factual findings show that Bahlul was on trial for something
that he himself did as part of al-Qaeda’s criminal plan to kill
nearly 3,000 civilians by flying planes into the World Trade
Center. See App. 116-17. And according to the evidence and
the commission’s findings, he did a lot. He played a
particularly valuable role supporting two of the 9/11
hijackers, Mohammed Atta and Ziad al Jarrah. Although at
the time he was not aware of the specifics of the September
11th plan, the prosecution introduced evidence that Bahlul
roomed with Atta and al Jarrah in Afghanistan, the
roommate’s role typically being to motivate and focus the
operatives, as well as to keep an eye on them in case they
decide to change their minds. Trial Tr. 555-56. More than
that, in a 2005 letter, Bahlul admitted that he arranged for
Atta and al Jarrah to pledge their loyalty oaths to bin Laden,
and “also typed their martyr wills on a computer and
personally handed it to Sheikh Usamah Bin-Landin [sic].”
App. 145 (Prosecution Ex. 15). Martyr wills are a crucial
aspect of al-Qaeda’s twisted ideology and operations. They
are declarations that a suicide operative reads into a camera,
describing in general terms the terrorist act he is yet to carry
out. Trial Tr. 554. The point of the videotaped message is to
motivate the operative, incite others to follow his example,
spread fear among al-Qaeda’s enemies, and allow the
organization to later prove its responsibility for the terrorist
act. Id. at 554, 798-99, 808. “I praise Almighty Allah,” wrote
Bahlul, “for allowing me to have [this] simple and indirect
role” in the 9/11 events. App. 145 (Prosecution Ex. 15).
                               11

     All of this amounts to Bahlul’s Pinkerton liability for at
least the murder of protected persons. See 10 U.S.C.
§§ 950v(a)(2), (b)(1) (outlawing “murder of protected
persons,” defined as “any person entitled to protection under
one or more of the Geneva Conventions”); see also Millett
Op. 31 (describing the MCA object offenses that violate
Article 3 of the Geneva Conventions). The record shows
that, during his membership in the conspiracy, Bahlul helped
further the conspiracy’s goal of committing substantive war
crimes. Even though the commission was instructed that
“[p]roof that [a substantive offense] of [murder of protected
persons, etc.] . . . actually occurred is not required,” Trial Tr.
848, it nonetheless twice confirmed just that; the commission
returned specific findings that Atta and al Jarrah committed
the September 11, 2001 attacks, App. 117, and that “at the
direction of Usama bin Laden, [Bahlul] researched the
economic effect of September 11, 2001, attacks on the United
States and provided the result of his research to Usama bin
Laden,” App. 117. The entire aim of the conspiracy was to
murder civilians. See App. 115; Trial Tr. 849 (explaining it
necessary to prove beyond a reasonable doubt that “the
agreement intended every element” of the substantive war
crimes). And the commission found that Bahlul purposefully
joined al-Qaeda, App. 116, was a conspiracy member during
and after the attacks, see App. at 117, as well as prepared the
martyr wills of Atta and al Jarrah “in preparation for the acts
of terrorism perpetrated . . . on September 11, 2001,” 4 App.
at 117 (emphasis added); see also Trial Tr. 849 (instructing
that “[t]he overt act . . . must be a clear indication that the
4
   Bahlul’s counsel suggests he transcribed the martyr wills
“apparently after the September 11th attacks.” Pet’r Br. 3 (citing
Pet’r App. 141-45). In any case, the commission specifically found
that Bahlul prepared them before September 11, 2001. App. 117.
                                 12
conspiracy is being carried out.”). In sum, the government
proved all of the Pinkerton elements beyond a reasonable
doubt.

     At oral argument, Bahlul’s counsel conceded that a
conviction under the Pinkerton doctrine does not violate the
Constitution. Oral Arg. Tr. 9-10. He could not have
answered otherwise, as joint criminal enterprise (“JCE”) is a
recognized theory of vicarious liability within the
international community. 5 See Hamdan v. Rumsfeld, 548
U.S. 557, 611 n.40 (2006) (plurality); Br. of Amici Curiae
Int’l Law Scholars 10; Br. of Amici Curiae Former Gov’t
Officials 6. There are actually three forms of JCE. See
Prosecutor v. Tadíc, Case No. IT-94-1-A, Judgment, ¶ 220
(Int’l Crim. Trib. for the Former Yugoslavia July 15, 1999).
The third variant, or “extended” JCE, occurs when there is “a
common purpose to commit a crime where one of the
perpetrators commits an act which, while outside the common
purpose, is nevertheless a natural and foreseeable
consequence of the effecting of that common purpose.”
Prosecutor v. Vasiljevic, Case No. IT-98-32-A, Judgment,
¶ 99 (Int’l Crim. Trib. for the Former Yugoslavia Feb. 25,
2004); see also id. at ¶¶ 94-101 (summarizing elements of
JCE I-III); Tadíc, Case No. IT-94-1-A, Judgment, at ¶ 204.
This is essentially the Pinkerton doctrine. 6 See Elies van

5
  “[V]ariously called joint criminal enterprise, common purpose, or
common plan liability,” JCE finds support “in World War II-era
jurisprudence and in cases from the [International Criminal
Tribunal for the Former Yugoslavia].” Brief for Specialists in
Conspiracy and International Law as Amici Curiae Supporting
Petitioner at 19, Hamdan v. Rumsfeld, 548 U.S. 557 (2006)
(No. 05-184) [hereinafter Hamdan Amici].
6
  The Hamdan Amici argued that JCE “differs sharply” from
Pinkerton liability, but offered little more than an explanation that
                                  13
Sliedregt, Criminal Responsibility in International Law, 14
EUR. J. CRIME, CRIM. L. & CRIM. JUST. 81, 97 (2006) (“The
closest national equivalent of Third Category JCE is the so-
called American concept of ‘Pinkerton conspiracy.’”); Jens
David Ohlin, Joint Intentions to Commit International
Crimes, 11 CHI. J. INT’L L. 693, 703 (2011) (“The standard
itself for JCE III stems from the Pinkerton v United States
doctrine . . . . Indeed, even the language in Tadíc is borrowed,
inter alia, from Pinkerton.”).

     Because the factual elements that were proven during
Bahlul’s prosecution were indistinguishable from a theory
recognized under international law, it does not offend the
Constitution.     See Bahlul, 792 F.3d at 24 (Tatel, J.,
concurring) (“[T]he weight of the Court's language in Quirin
strongly indicates that the law-of-war exception is exclusively
international.”). As a result, I do not believe we should reach
out and decide additional constitutional issues not necessary
to resolve this appeal, which is why I am unwilling to wade
into the waters pursued by Judge Kavanaugh. See Ex parte
Quirin, 317 U.S. 1, 45-46 (1942) (“We have no occasion now
to define with meticulous care the ultimate boundaries of the
jurisdiction of military tribunals to try persons according to
the law of war. It is enough that petitioners here, upon the

JCE, as a theory of vicarious liability, is not the same as an inchoate
offense. Hamdan Amici at 20. Amici in our case do not make a
similar claim. That argument is perhaps driven by the need to
“distance” JCE from “a formulation that sounds too much like
conspiracy. The received wisdom among international lawyers is
that conspiracy is a decidedly common law doctrine that finds
insufficient international support to be considered part of
international criminal law. Consequently, if JCE amounts to ersatz
conspiracy, it will be rejected too.” Jens David Ohlin, Joint
Intentions to Commit International Crimes, 11 CHI. J. INT’L L. 693,
696 (2011).
                              14
conceded facts, were plainly within those boundaries . . . .”);
see also Rasul v. Bush, 542 U.S. 466, 485 (2004) (limiting its
holding to only “[w]hat is presently at stake” before the
Court). It is first and foremost a conviction we are reviewing.
When considering the particular record before us, it shows
that the government proved Bahlul joined a conspiracy to
murder Americans prior to the September 11, 2001 attacks,
remained a member following those attacks, and himself
committed overt acts in furtherance of the conspiracy both
before and after September 11, 2001. See App. 116-17. As
tantamount to a Pinkerton conviction, it does not raise the
concerns that have caused critics to reject the prosecution of
inchoate conspiracy as a violation of international law. The
charge was not overbroad, the commission was never
instructed that the acts or intentions of Bahlul’s co-
conspirators should be deemed his acts or intentions, there
was a completed offense, and Bahlul admitted that he himself
committed several overt acts in furtherance of the completed
offense. See Al Bahlul v. United States, 767 F.3d 1, 7 (D.C.
Cir. 2014) (en banc). His conviction is very much the
opposite of the “overbroad application of the conspiracy
principle . . . [that] drag[s] innocent people into the
prosecution’s net.” Br. of Amici Curiae Int’l Law Scholars 6
(quoting Telford Taylor, Anatomy of the Nuremberg Trials: A
Personal Memoir 553 (1992)).

                             ***
     When I look at what Bahlul was really convicted of, I see
a war crime. Thus, his conviction does not violate the law of
nations, or our separation of powers – even under a de novo
standard. I further concur with rejecting Bahlul’s additional
constitutional challenges on the bases set forth in section IV
of Judge Millet’s opinion. For these reasons we should affirm
the conviction.
     ROGERS, TATEL, and PILLARD Circuit Judges, dissenting:
When confronted with the facts of this case, one is tempted to
search for a way to sustain Ali Hamza Ahmad Suliman al
Bahlul’s conviction for the crime of inchoate conspiracy to
violate the laws of war. After all, he has admitted that he
swore an oath of loyalty to Osama bin Laden, served as bin
Laden’s personal secretary, and made al Qaeda recruitment
videos. But tempting as it may be, too much is at stake to
affirm. The prosecution of al Bahlul in a law-of-war military
commission for inchoate conspiracy infringes the judiciary’s
power to preside over the trial of all crimes, as set forth in
Article III of the Constitution. History and precedent have
established a narrow, atextual exception to Article III under
which the military may try enemy belligerents for offenses
against the international “laws of war,” but inchoate
conspiracy is not such an offense.

     The challenges of the war on terror do not necessitate
truncating the judicial power to make room for a new
constitutional order. “The laws and Constitution are designed
to survive, and remain in force, in extraordinary times.
Liberty and security can be reconciled; and in our system they
are reconciled within the framework of the law.” Boumediene
v. Bush, 553 U.S. 723, 798 (2008). The exceptional authority
the government seeks here falls outside the bounds
established by more than a century of constitutional practice.
Equally important, the government here has never contended
that such authority is even necessary. The prosecution could
have charged al Bahlul with recognized war crimes using
conspiracy as a theory of liability or it could have charged
him before an Article III court with inchoate conspiracy and
any number of other crimes triable there but it chose neither
course. The circumstances of this case thus present no
occasion for the judicial branch to abandon its responsibility
to enforce the constitutional plan of separated powers.
                              2
     Accordingly, for the reasons set forth below, we
respectfully dissent from the judgment affirming al Bahlul’s
conviction. We begin in Part I with the standard of review,
concluding—along with the majority of this court—that al
Bahlul’s separation-of-powers claim is properly reviewed de
novo. In Part II we set forth the relevant precedent governing
that claim, explaining that it fails to provide support for the
government’s prosecution of al Bahlul in a military
commission for the crime of inchoate conspiracy. We also
respond to the government’s key arguments for upholding al
Bahlul’s conspiracy conviction, finding none persuasive.
Part III then responds to several of our colleagues’ arguments,
and Part IV addresses the potential consequences of the
government’s asserted authority. We conclude by
emphasizing that, in keeping with our Constitution’s
commitment to judicial independence, a majority of this court
declines to cede the requested judicial authority to the
military.

                              I.

     As a threshold matter, the government argues that during
the military commission proceedings, al Bahlul failed to raise
each of the challenges he now advances against his
conspiracy conviction and that he has, therefore, forfeited
them. Resp’t’s Br. 17–18; see Millett Op. at 8–11. If al Bahlul
did forfeit them, this court would ordinarily review those
claims only for plain error—a highly deferential standard. See
Al Bahlul v. United States (Al Bahlul I), 767 F.3d 1, 9–10
(D.C. Cir. 2014) (en banc). The challenge we address,
however, asks whether trying al Bahlul for the crime of
inchoate conspiracy in a law-of-war military commission
violates the separation-of-powers principles enshrined in
Article III, § 1 of the Constitution. That question warrants de
novo review.
                                3

     As this court has recognized, a party can waive or forfeit
the argument that an opposing party has waived or forfeited a
claim. See, e.g., Solomon v. Vilsack, 763 F.3d 1, 13 (D.C. Cir.
2014) (“By failing to argue forfeiture or a failure to properly
plead the claims before the district court, the Secretary has—
in a word—forfeited his forfeiture argument here.”); United
States v. Delgado-Garcia, 374 F.3d 1337, 1340 (D.C. Cir.
2004) (holding that, by failing to advance it, the government
had “waived its waiver argument”). Here, the government has
undoubtedly forfeited any argument it might have had that al
Bahlul failed to pursue (and thereby forfeited) his “structural”
Article III claim. In its first en banc brief to this court, the
government forcefully argued that al Bahlul had forfeited his
ex post facto challenge by failing to raise it at trial and that
the challenge was consequently subject to plain error review.
Brief for the United States 63, Al Bahlul I, 767 F.3d 1
(No. 11-1324), 2013 WL 3479237, at *63. But the
government never suggested that al Bahlul had similarly
forfeited his Article III objection or that this court should
review that claim only for plain error. Id. at 70–71. That was
so even though al Bahlul had expressly sought de novo review
of that claim. See Brief for Petitioner 13, Al Bahlul I, 767 F.3d
1 (No. 11-1324), 2013 WL 2325912, at *13. Later, on remand
to the original panel, the government again failed to argue that
al Bahlul had forfeited his structural Article III claim. Instead,
it expressed its belief that the claim was nonforfeitable and
thus subject to de novo review. See Transcript of Oral
Argument at 29–30, Al Bahlul v. United States (Al Bahlul II),
792 F.3d 1 (D.C. Cir. 2015) (No. 11-1324) (“Q: Are you also
saying that the structural Article 3 claim is forfeitable? A: I
am saying that argument is not forfeitable.”). Now, after four
years of litigation before this court, the government changes
its tune and, for the very first time, argues that al Bahlul
forfeited the structural claim at trial. Because the government
                               4
long ago “forfeited [its] forfeiture argument” with respect to
that claim, Solomon, 763 F.3d at 13, this court properly
reviews it de novo. See Kavanaugh Op. at 3 n.1.

     Even if the government had, from the outset, pressed its
view that al Bahlul forfeited his structural Article III claim,
we would still review it de novo. The Supreme Court has
made clear that ordinary forfeiture and waiver principles do
not apply to structural Article III claims like this one. As the
Court has explained, Article III, § 1, which vests “[t]he
judicial Power of the United States, . . . in one supreme Court,
and in such inferior Courts as the Congress may from time to
time ordain and establish,” serves two distinct purposes. First,
it “safeguard[s] litigants’ right to have claims decided before
judges who are free from potential domination by other
branches of government.” Commodity Futures Trading
Commission v. Schor, 478 U.S. 833, 848 (1986) (internal
quotation marks omitted). Second, it “protect[s] the role of the
independent judiciary within the constitutional scheme of
tripartite government.” Id. (internal quotation marks omitted).
As with other constitutional rights, litigants can waive or
forfeit their personal right to an Article III adjudication. See
id. at 848–49; Wellness International Network, Ltd. v. Sharif,
135 S. Ct. 1932, 1949 (2015) (remanding the case for the
lower court to determine whether the litigant forfeited his
personal right to an Article III adjudication). But because the
provision also protects “institutional interests that the parties
cannot be expected to protect,” the Supreme Court has held
that when courts are presented with structural Article III, § 1
claims, “notions of consent and waiver cannot be dispositive.”
Schor, 478 U.S. at 851. Instead, where structural principles
are implicated, courts may ignore a party’s waiver or
forfeiture to consider an Article III, § 1 claim de novo. See,
e.g., id. at 850–57 (examining whether an Article I tribunal’s
adjudication of a state law counterclaim impermissibly
                               5
infringed on the judiciary’s domain despite the petitioning
party having waived his right to pursue the claim in an
Article III tribunal).

     The Court has repeatedly reaffirmed this approach. In
Plaut v. Spendthrift Farm, Inc., the Court stated that courts
have discretion to excuse waivers where parties purport to
waive “doctrines central to the courts’ structural
independence” such as res judicata. 514 U.S. 211, 231–32
(1995). Most recently, in Wellness International Network v.
Sharif, the Court demonstrated once again that a litigant’s
waiver or forfeiture of the “personal right” to an
Article III adjudication presents no bar to courts’
consideration of structural Article III claims on the merits.
135 S. Ct. at 1943 (quoting Schor, 478 U.S. at 850) (emphasis
added). Despite recognizing that Sharif may have forfeited his
personal right to have a so-called Stern claim adjudicated
before an Article III judge, id. at 1941 n.5, 1949, the Court
proceeded to consider whether allowing bankruptcy courts to
adjudicate Stern claims with the parties’ consent would
“impermissibly threaten the institutional integrity of the
Judicial Branch,” id. at 1944–46 (internal quotation marks and
alteration omitted). Thus, rather than following ordinary rules
of appellate procedure under which it would have declined to
review a potentially waived or forfeited claim, the Court
disregarded the potential forfeiture and considered the
structural issue on the merits.

     Putting aside whether cases like Schor and Sharif should
be read to hold that structural Article III, § 1 claims can never
be waived or forfeited, see Al Bahlul II, 792 F.3d at 3–7
(explaining how the Schor line of cases may be read to
prohibit waiver or forfeiture of structural Article III claims);
id. at 23–24 (Tatel, J., concurring) (same), those cases stand,
at the very least, for the proposition that courts should not
                               6
reflexively apply ordinary rules of waiver and forfeiture to
dispose of such claims. Instead, under that line of cases,
courts may exercise their discretion to protect the judiciary’s
role within our system of government. We believe this is one
of those cases in which the court should exercise that
discretion.

      To be sure, al Bahlul is hardly a sympathetic litigant, and
it is tempting to cut him no slack. Not only has he admitted
nearly all of the allegations against him, including that he
pledged an oath of loyalty to Osama bin Laden and produced
al Qaeda recruiting materials, but during his trial he “flatly
refused” to put on any defense, conducting a self-styled
boycott instead. Al Bahlul I, 767 F.3d at 5–7, 10. The question
presented by Schor and its progeny, however, is not whether
this court should exercise its discretion for al Bahlul’s sake.
The question is whether the court should exercise its
discretion to “safeguard[] the role of the Judicial Branch in
our tripartite system.” Schor, 478 U.S. at 850. In our view, the
answer here is plainly yes.

     As Justice Kennedy observed in Hamdan v. Rumsfeld,
“[t]rial by military commission raises separation-of-powers
concerns of the highest order.” 548 U.S. 557, 638 (2006)
(Kennedy, J., concurring). Here, al Bahlul presents substantial
questions as to whether the political branches have invaded
the judiciary’s domain. Specifically, he argues that Congress
and the executive branch have ventured beyond the scope of
the Article III exception for law-of-war military commissions
sanctioned in Ex parte Quirin, 317 U.S. 1 (1942), a case four
Justices recently described as “the high-water mark of
military power to try enemy combatants for war crimes.”
Hamdan, 548 U.S. at 597 (plurality opinion). Determining
whether such an expansion of military power is constitutional
is especially critical as our nation enters a new era in which
                               7
many of the traditional constraints on the political branches’
authority to prosecute individuals in military commissions—
including wars’ temporal limits and the presence of clearly
defined enemies—are dissipating. See, e.g., Legal Issues
Regarding Military Commissions and the Trial of Detainees
for Violations of the Law of War: Hearing Before the Senate
Committee on Armed Services, 111th Cong. 11 (2009)
(statement of David Kris, Assistant Attorney General,
National Security Division, Department of Justice) (“In the
past, military commissions have been associated with a
particular conflict of relatively short duration. In the modern
era, . . . the conflict could continue for a much longer time.”).

     In this new context, it is also essential that courts give
Congress and the President clear guidance on the offenses that
can be tried by law-of-war military commissions. The purpose
of such tribunals has long been to “dispense swift justice” in
the midst of battle. Hamdan, 548 U.S. at 607 (plurality
opinion). But in recent years, the uncertainty surrounding the
legal limits on military commissions has made this form of
justice anything but swift. Indeed, Congress first codified
conspiracy as an offense triable by military commission a
decade ago, and al Bahlul was convicted of inchoate
conspiracy over seven years ago. Nevertheless, the legitimacy
of that charge remains in doubt. Because clear limits can
assist Congress and the Executive as they continue to combat
al Qaeda and its associated forces and as they consider the
United States’ role in future conflicts, it would be unwise to
put off final resolution of the commissions’ authority to
preside over such charges for still more years to come. Cf. id.
at 589 (majority opinion) (declining the government’s request
to abstain from reaching the merits of an unlawful enemy
combatant’s challenge to a military commission’s authority
because, among other things, he and the government both had
                                 8
“a compelling interest in knowing in advance whether [he]
may be tried by a military commission”).

     Asked at oral argument why the court should not exercise
its discretion to review this question de novo, the government
principally argued that constitutional avoidance principles
counseled against it. See Oral Arg. Tr. 58–60 (Dec. 1, 2015).
But on that logic, courts would never exercise their discretion
to consider structural Article III claims because such claims
always implicate constitutional questions. That outcome
would stand in direct conflict with the Supreme Court’s
instruction that a party’s waiver or forfeiture of a structural
Article III claim not be dispositive as to whether a court
reaches the claim on the merits.

     Although acknowledging that “Schor affords this court
some discretion to review a forfeited Article III claim de
novo,” Millett Op. at 17, Judge Millett would decline to
exercise that discretion here, id. at 17–27. In our view, her
reasons for doing so insufficiently account for the central
teaching of Schor and its progeny and overstate the
consequences of exercising our discretion. In particular,
although it is true that the Supreme Court has typically
invoked Schor to ignore a party’s waiver or forfeiture of a
structural Article III claim in civil cases involving
adjudicatory systems premised on the parties’ consent—that
is, in cases where parties necessarily waived their right to
later challenge the adjudication of their claims in non-
Article III fora, see id. at 20–21—those cases recognize that
Article III, § 1 protects the judiciary’s role in our system of
government and that the judiciary cannot be wholly dependent
on litigants to assert its institutional interests, see, e.g., Schor,
478 U.S. at 851. This principle—that there are Article III, § 1
guarantees that are not the parties’ to waive or forfeit—
applies at least as strongly in criminal as in civil cases. See
                                9
Peretz v. United States, 501 U.S. 923, 925, 937–39 (1991)
(acknowledging in the context of a criminal case that, under
Schor, there may be structural principles litigants cannot
waive or forfeit); id. at 950 (Marshall, J., dissenting)
(“Although parties may waive their personal guarantee of an
independent Article III adjudicator, parties may not waive
Article III’s structural guarantee.” (internal citation omitted)).

     For similar reasons, Judge Millett’s concern that the court
not “reward[]” al Bahlul for his refusal to participate in the
military proceedings and that excusing al Bahlul’s forfeiture
would undermine the judicial process, Millett Op. at 21,
misses the point. As already noted, the court, in exercising its
discretion to consider the matter de novo, is doing so for the
judicial branch’s own benefit, not for al Bahlul’s. And
although enforcing forfeitures generally ensures timely raised
objections, deters sandbagging of the other party, and enables
timely fact-finding and error correction, see id. at 9–10, those
concerns are not compelling here because future litigants will
have no way of knowing in advance whether courts will
exercise their discretion to consider structural Article III
claims. Moreover, any disruption to normal appellate process,
see id. at 21–22, is “plainly insufficient to overcome the
strong interest of the federal judiciary in maintaining the
constitutional plan of separation of powers.” Glidden Co. v.
Zdanok, 370 U.S. 530, 536 (1962); see Kuretski v.
Commissioner of Internal Revenue Service, 755 F.3d 929, 936
(D.C. Cir. 2014).

     In sum, although the government now claims that al
Bahlul forfeited his personal right to a trial in an Article III
court, it conceded otherwise at every prior stage of this
litigation, thereby “forfeiting the forfeiture.” In any event,
strong reasons counsel in favor of exercising our discretion to
consider the matter de novo. We therefore ask whether
                               10
Congress has, in the Military Commissions Act of 2006,
impermissibly encroached on the province of Article III
courts by authorizing law-of-war military commissions to try
alien unlawful enemy combatants for the crime of conspiracy.
On that question, too, we think the answer is clear: it has.

                               II.

     By its text, Article III commits the entire “judicial Power
of the United States” to the Supreme Court and “such inferior
Courts as the Congress may from time to time ordain and
establish.” U.S. CONST. art. III, § 1. It further provides that
“[t]he judicial Power shall extend to all Cases, in Law and
Equity, arising under th[e] Constitution, the Laws of the
United States, and Treaties made, or which shall be made,
under their Authority,” id. § 2, cl. 1; that the judges who sit on
Article III courts shall enjoy life tenure and salary protections,
id. § 1; and that “[t]he Trial of all Crimes, except in Cases of
Impeachment, shall be by Jury,” id. § 2, cl. 3.

     Over time, the Supreme Court has recognized certain
limited exceptions, based on principles “rooted in history and
the Constitution,” Northern Pipeline Construction Co. v.
Marathon Pipe Line Co., 458 U.S. 50, 74 (1982) (plurality
opinion), to Article III’s commitment of the judicial power to
constitutional courts and the judge and jury protections that
go along with it. Thus, Congress may create non-Article III
courts to try cases in the District of Columbia and U.S.
territories. Palmore v. United States, 411 U.S. 389, 390–91
(1973); American Insurance Co. v. 356 Bales of Cotton, 26
U.S. (1 Pet.) 511, 546 (1828); see U.S. CONST. art. I, § 8,
cl. 17. It may assign to administrative agencies the
adjudication of private disputes involving “public rights”
stemming from federal regulatory programs. Murray’s Lessee
v. Hoboken Land & Improvement Co., 59 U.S. (18 How.) 272,
                              11
284 (1855); see U.S. CONST. art. I, § 8, cl. 1. It may also
assign certain criminal prosecutions of individuals connected
to military service to courts martial. Dynes v. Hoover, 61 U.S.
(20 How.) 65, 79 (1857); see U.S. CONST. art I, § 8, cl. 14.
Finally, at issue here, the Supreme Court has upheld a narrow
Article III carve-out for military commissions. See Quirin,
317 U.S. at 39–41.

     Historically, the government has established military
commissions in three situations in which wartime necessity
has required them: First, it has established commissions to
operate as general courts in areas under martial law. See Ex
parte Milligan, 71 U.S. (4 Wall.) 2, 127 (1866) (recognizing
that “there are occasions when martial rule can be properly
applied”). Second, the government has employed military
commissions as general courts in areas that the military
temporarily occupies. See Madsen v. Kinsella, 343 U.S. 341
(1952) (upholding a military commission’s jurisdiction to try
a civilian for murder in occupied Germany). Third, the
government has created commissions to punish enemy
belligerents who commit offenses against the laws of war
during an armed conflict. See Quirin, 317 U.S. 1; see also
Hamdan, 548 U.S. at 595–97 (plurality opinion); WILLIAM
WINTHROP, MILITARY LAW AND PRECEDENTS 836–40 (rev. 2d
ed. 1920) [hereinafter WINTHROP, MILITARY LAW].

    The parties agree that al Bahlul was tried before the third
type of tribunal—that is, a law-of-war military commission.
They part ways, however, in defining the permissible scope of
those commissions’ jurisdiction. Al Bahlul contends that law-
of-war military commissions may try only offenses against
the international laws of war, and that the sole remaining
charge here, the standalone crime of conspiracy, is not such
an offense. The government responds to al Bahlul’s
constitutional challenge in two ways. First, it contends that
                              12
Congress may authorize military commissions to try enemy
belligerents for violations of the international laws of war as
well as any other offenses Congress defines as violations of
the “laws of war.” Following from this point, the government
asserts that although conspiracy to commit war crimes is not
recognized as an international law-of-war offense, Congress
in the Military Commissions Act of 2006 lawfully vested
military commissions with authority to try individuals like al
Bahlul for the crime of conspiracy. In doing so, the
government takes the position that international law imposes
no constraints on the kinds of offenses Congress can make
triable by military commission. Alternatively, the government
takes the slightly narrower position that the military can try
enemy belligerents for international war crimes, as well as
any offenses punishable under a “U.S. common law of war,”
by which the government means any offenses traditionally
tried by military commission in the United States. On this
point, the government contends that there is sufficient
historical precedent for trying conspiracy before law-of-war
military commissions, and that the charge against al Bahlul
was, therefore, lawful. Based on the Supreme Court precedent
most directly on point—which we, as a lower court, must
follow—al Bahlul has the better of these arguments.

                              A.

     The principal decision that governs here is Ex parte
Quirin, a case in which seven Nazi saboteurs challenged the
government’s authority to try them in a military, as opposed
to civilian, tribunal. Prior to their arrests, the saboteurs had
received military training at a sabotage school in Germany,
traveled to the United States by submarine, discarded their
military uniforms once ashore, and then traveled to various
locales in civilian dress with the apparent intent to destroy
U.S. war industries and facilities. 317 U.S. at 21. After they
                              13
were apprehended and detained, President Roosevelt issued
an executive order establishing a military commission to try
them for offenses against the laws of war and the Articles of
War. Id. at 22. Pursuant to that order, the Army Judge
Advocate General prepared four charges against the
saboteurs, which read as follows:

    1. Violation of the law of war.
    2. Violation of Article 81 of the Articles of War,
    defining the offense of relieving or attempting to
    relieve, or corresponding with or giving intelligence
    to, the enemy.
    3. Violation of Article 82, defining the offense of
    spying.
    4. Conspiracy to commit the offenses alleged in
    charges 1, 2 and 3.

Id. at 23.

     Focusing on the first charge alone, the Supreme Court
upheld the commission’s jurisdiction to try the defendants. It
observed that “[a]n important incident to the conduct of war is
the adoption of measures by the military command not only to
repel and defeat the enemy, but to seize and subject to
disciplinary measures those enemies who in their attempt to
thwart or impede our military effort have violated the law of
war.” Id. at 28–29. It further found that Congress had
authorized the use of law-of-war military commissions in
Article 15 of the Articles of War. Article 15 directed that “the
provisions of the[] articles conferring jurisdiction upon
courts-martial shall not be construed as depriving military
commissions . . . of concurrent jurisdiction in respect of
offenders or offenses that by statute or by the law of war may
be triable by such military commissions.” Id. at 27–28
                               14
(emphasis added). By enacting that provision, the Court
explained, Congress had

     exercised its authority to define and punish offenses
     against the law of nations by sanctioning, within
     constitutional limitations, the jurisdiction of military
     commissions to try persons for offenses which,
     according to the rules and precepts of the law of
     nations, and more particularly the law of war, are
     cognizable by such tribunals.

Id. at 28.

       Stating that the term “law of war” refers to a “branch of
international law,” id. at 29 (emphasis added); see also id. at
27–28, the Court proceeded to consider whether the
defendants had been charged with a violation of the
international rules governing armed conflicts, id. at 30–31,
35–36. It ultimately concluded that they had been, expressing
its belief that passing behind enemy lines in civilian dress
with the purpose of committing hostile acts was then an
offense under international law. Id. at 31. According to the
Court, the “precept” that “those who during time of war pass
surreptitiously from enemy territory into our own, discarding
their uniforms upon entry, for the commission of hostile acts
involving destruction of life or property, [are] . . . punishable
. . . by military commission” was “so recognized in practice
both here and abroad” and “so generally . . . accepted as valid
by authorities on international law” that it had to be “regarded
as a rule or principle of the law of war recognized by this
Government by its enactment of the Fifteenth Article of War.”
Id. at 35–36.

    After concluding that Congress had lawfully authorized
the military-commission trial of the offense specified in the
                               15
first charge, the Court turned to consider whether, despite
Congress’s authorization, the jury trial protections in
Article III, § 2 and the Fifth and Sixth Amendments
nonetheless barred the saboteurs’ prosecution in a military
commission. Concluding that they did not, the Court
emphasized that military tribunals “are not courts in the sense
of the Judiciary Article,” id. at 39, and that the adoptions of
Article III, § 2 and the Fifth and Sixth Amendments were in
no way intended to deprive the military of its traditional
ability to try enemy belligerents for offenses against the laws
of war, id. at 39–41. Violations of the laws of war, the Court
observed, have, “since the founding of our government,” been
cognizable by military tribunals. Id. at 41. For support, the
Court pointed to an 1806 statute subjecting alien spies to
death, “according to the law and usage of nations, by sentence
of a general court martial.” Id. at 41. That statute, the Court
explained, provided a “contemporary construction of both
Article III, § 2, and the Amendments as not foreclosing trial
by military tribunals, without a jury, of offenses against the
law of war committed by enemies not in or associated with
our Armed Forces.” Id. at 41. Thus, in Quirin the Supreme
Court recognized an exception to Article III and its judge and
jury protections for military trials of violations of the “laws of
war”—a body of law that, as noted above, the Court described
as international. Id. at 29.

     For over seventy years, the Court has treated the phrase
“law of war” as referring to a body of international law, thus
reinforcing the idea that Quirin recognized an Article III
exception for international law-of-war offenses. For instance,
only four years after Quirin, in In re Yamashita, 327 U.S. 1
(1946), the Court, reaffirming Quirin’s “governing
principles,” id. at 9, considered whether a military
commission could try a Japanese Commanding General for
the “plain violations of the law of war” committed by his
                              16
troops, based on a command theory of responsibility, id. at 16.
Continuing to rely on the Articles of War as having provided
congressional authorization for military commissions to try
enemy combatants for offenses against the “law of war,” id. at
7, the Court concluded that the commission had jurisdiction
over the specified offense, id. at 17–18. Importantly for our
purposes here, the Court looked to international sources to
determine whether the charges specified offenses against the
“laws of war.” Id. at 15–16.

     Four years later, the Court again addressed the scope of
law-of-war military commissions’ jurisdiction in Johnson v.
Eisentrager, 339 U.S. 763 (1950). The Court reiterated the
principles laid out in Quirin and Yamashita, observing that
“[t]he jurisdiction of military authorities, during or following
hostilities, to punish those guilty of offenses against the laws
of war is long-established.” Id. at 786 (emphasis added). It
again looked only to international sources to conclude that the
conduct with which the petitioners were charged—“[b]reach
of the terms of an act of surrender”—violated the
international laws governing armed conflicts. Id. at 787–88.

     Quirin, as reinforced by Yamashita and Eisentrager, thus
upheld the authority of military commissions to try enemy
belligerents for violations of the international laws of war
without running afoul of Article III. But those cases went no
further. And while it is true that those cases did not address
the question presented here—i.e., whether military
commissions can exercise jurisdiction over crimes
unrecognized under international law without offending
Article III’s structural principles—we, as a lower court,
should be hesitant to stretch the exception recognized in those
cases in the ways the government suggests. For one thing, a
Supreme Court plurality has already described Quirin as “the
high-water mark of military power to try enemy combatants
                               17
for war crimes.” Id. at 597. For another, law-of-war military
commissions present an atextual exception to Article III’s
vesting of the judicial power in civilian courts, requiring that
we construe the exception narrowly. Finally, expanding the
scope of military commissions’ jurisdiction would erode their
historical and theoretical underpinnings as an important
mechanism for punishing enemy combatants who fail to abide
by the internationally agreed upon rules governing the
conduct of war.

                               B.

     Given the foregoing principles, the Article III inquiry in
this case turns on whether conspiracy to commit war crimes is
an offense under the international laws of war. As the
government candidly and rightly concedes, it is not. See Brief
for the United States 34, Al Bahlul I, 767 F.3d 1 (No. 11-
1324), 2013 WL 3479237, at *34 (“[T]he government has
acknowledged that conspiracy has not attained recognition at
this time as an offense under customary international law.
This is true even when the objects of the conspiracy are
offenses prohibited by customary international law, as some
of them are in this case.” (internal citation omitted)); see also
Government Response to Defense Motion to Dismiss for Lack
of Lack of [sic] Jurisdiction Over the Charge of Conspiracy,
AE048A, at 21–22, United States v. Al-Nashiri (M.C. Mar.
26, 2012) (“[H]istory reflects a lack of international
consensus for treating the standalone offense of conspiracy as
a war crime as a matter of customary international law . . . .”
(emphasis omitted)).

    To begin, neither the Hague nor the Geneva
Conventions—“the major treaties on the law of war,”
Hamdan, 548 U.S. at 604 (plurality opinion)—mention
conspiracy, see Convention with Respect to the Laws and
                              18
Customs of War on Land (Hague II), July 29, 1899, 32 Stat.
1803; Convention Respecting the Laws and Customs of War
on Land (Hague IV), Oct. 18, 1907, 36 Stat. 2277; Geneva
Convention for the Amelioration of the Condition of the
Wounded and Sick in Armed Forces in the Field, Aug. 12,
1949, 6 U.S.T. 3114, 75 U.N.T.S. 31; Geneva Convention for
the Amelioration of the Condition of Wounded, Sick and
Shipwrecked Members of Armed Forces at Sea, Aug. 12,
1949, 6 U.S.T. 3217, 75 U.N.T.S. 85; Geneva Convention
Relative to the Treatment of Prisoners of War, Aug. 12, 1949,
6 U.S.T. 3316, 75 U.N.T.S. 135; Geneva Convention Relative
to the Protection of Civilian Persons in Time of War, Aug. 12,
1949, 6 U.S.T. 3516, 75 U.N.T.S. 287; Protocol Additional to
the Geneva Conventions of 12 August 1949, and Relating to
the Protection of Victims of International Armed Conflicts
(Protocol I), June 8, 1977, 1125 U.N.T.S. 3; Protocol
Additional to the Geneva Conventions of 12 August 1949,
and Relating to the Protection of Victims of Non-International
Armed Conflicts (Protocol II), June 8, 1977, 1125 U.N.T.S.
609.

     International tribunals established for the prosecution of
war crimes, crimes against humanity, and crimes against
peace have also declined to recognize conspiracy as a war
crime. For instance, the London Charter, which established
the International Military Tribunal at Nuremberg for the
prosecution of major Nazi war criminals after World War II,
did not list conspiracy among the punishable war crimes. See
Agreement for the Prosecution and Punishment of the Major
War Criminals of the European Axis, Aug. 8, 1945, 82
U.N.T.S. 279 (London Charter). Indeed, the tribunal
dismissed a charge for conspiracy to commit war crimes and
crimes against humanity because “the Charter d[id] not define
as a separate crime any conspiracy except the one to commit
acts of aggressive war.” 22 TRIAL OF THE MAJOR WAR
                              19
CRIMINALS BEFORE THE INTERNATIONAL MILITARY TRIBUNAL
469 (1948).

    The same is true of the charter for the International
Military Tribunal for the Far East, see Supreme Commander
for the Allied Powers at Tokyo, General Order No. 20,
Special Proclamation for the Establishment of an International
Military Tribunal for the Far East, Apr. 26, 1946, T.I.A.S. No.
1589, 4 Bevans 20; International Military Tribunal for the Far
East, Judgment of 4 November 1948, in 22 THE TOKYO WAR
CRIMES TRIAL: THE COMPLETE TRANSCRIPTS OF THE
PROCEEDINGS OF THE INTERNATIONAL MILITARY TRIBUNAL
FOR THE FAR EAST 48,448–51 (R. John Pritchard and Sonia
M. Zaide eds. 1981), and the law conferring authority on the
forces occupying post-war Germany to punish lower-level
Nazi officials for war crimes, see, e.g., 2 TRIALS OF WAR
CRIMINALS BEFORE THE NURENBERG MILITARY TRIBUNALS
UNDER CONTROL COUNCIL LAW NO. 10, at 122, 174 (1949).
As a tribunal established under the latter explained, “[N]either
the Charter of the International Military Tribunal nor Control
Council Law No. 10 has defined conspiracy to commit a war
crime or crime against humanity as a separate substantive
crime; therefore, this Tribunal has no jurisdiction to try any
defendant upon a charge of conspiracy considered as a
separate substantive offense.” Id.

     More recently, the statutes for the International Criminal
Tribunal for the Former Yugoslavia, the International
Criminal Tribunal for Rwanda, and the Special Court for
Sierra Leone did not identify conspiracy as a violation of the
laws of war. See Statute of the International Tribunal for the
Former Yugoslavia, annexed to Report of the Secretary-
General Pursuant to Paragraph 2 of Security Council
Resolution 808 (1993) S/25704 (May 3, 1993), adopted by
S.C. Res. 827 (May 25, 1993), reprinted in 32 I.L.M. 1159
                              20
[hereinafter ICTY Statute]; Statute of the International
Tribunal for Rwanda, adopted by S.C. Res. 955, U.N. Doc.
S/RES/955 (1994), reprinted in 33 I.L.M. 1598 [hereinafter
ICTR Statute]; Statute of the Special Court for Sierra Leone,
Jan. 16, 2002, 2178 U.N.T.S. 138. And, quite tellingly, the
Rome Statute, which established the International Criminal
Court and which “catalogues an extensive list of international
war crimes,” Hamdan v. United States, 696 F.3d 1238, 1251
(D.C. Cir. 2012), overruled on other grounds, Al Bahlul I, 767
F.3d at 11, does not list conspiracy to commit war crimes as
itself a war crime. See Rome Statute of the International
Criminal Court, July 17, 1998, 2187 U.N.T.S. 90 [hereinafter
Rome Statute].

     Other sources on the laws of war likewise recognize that
international law has declined to adopt conspiracy to commit
war crimes as a standalone offense. See, e.g., ANDREA
BIANCHI & YASMIN NAQVI, INTERNATIONAL HUMANITARIAN
LAW AND TERRORISM 244 (2011); ANTONIO CASSESE,
INTERNATIONAL CRIMINAL LAW 191, 197 (2003). Domestic
jurists confirm that international law has long rejected
conspiracy as a law-of-war offense. Professor George Fletcher
observes that, “Since 1948 and the residue of the Genocide
Convention in the statutes of the ad hoc tribunals, every
relevant international treaty on international humanitarian law
or international criminal law had deliberately avoided the
concept and language of conspiracy.” George P. Fletcher,
Hamdan Confronts the Military Commissions Act of 2006, 45
COLUM. J. TRANSNAT’L L. 427, 448 (2007). William
Winthrop, the “Blackstone of military law,” Reid v. Covert,
354 U.S. 1, 19 (1957) (plurality opinion), noted that
conspiracy was not a law-of-war offense. WINTHROP,
MILITARY LAW, supra, at 842, cited in Hamdan, 548 U.S. at
597. Where Winthrop listed the law-of-war violations that had
                               21
principally been charged in U.S. military commissions,
conspiracy was not among them. See id. at 839–40.

     Significantly for the issue before us, international law has
adopted conspiracy as a standalone offense in only two
circumstances. First, it has recognized conspiracy to commit
genocide as a crime against humanity. See, e.g., Convention
on the Prevention and Punishment of the Crime of Genocide,
art. 3(b), Dec. 9, 1948, 78 U.N.T.S. 277; ICTY Statute, supra,
art. 4; ICTR Statute, supra, art. 2. Second, it has
acknowledged conspiracy to wage aggressive war as a crime
against peace. See London Charter, art. 6(a). Outside of these
two contexts, however, the crime of conspiracy has gained no
traction in international law. Hamdan, 548 U.S. at 610
(plurality opinion). Those exceptions are plainly not at issue
here, for al Bahlul was charged with neither.

     The limited international acceptance of conspiracy is not
due to a lack of consideration. For instance, during
negotiations over the London Charter in 1945, the concept of
conspiracy as a separate offense generated considerable
debate. See BRADLEY F. SMITH, REACHING JUDGMENT AT
NUREMBERG 51 (1977); ROBERT H. JACKSON, REPORT OF
UNITED STATES REPRESENTATIVE TO THE INTERNATIONAL
CONFERENCE ON MILITARY TRIALS, at vii (1947) (“Another
point on which there was a significant difference of viewpoint
concerned the principles of conspiracy as developed in Anglo-
American law, which are not fully followed nor always well
regarded by Continental jurists.”). Although the prosecution,
led by Justice Robert Jackson, charged the defendants with
conspiracy to commit war crimes and crimes against
humanity, the tribunal rebuffed the effort, see 22 TRIALS OF
THE MAJOR WAR CRIMINALS BEFORE THE INTERNATIONAL
MILITARY TRIBUNAL 412, 469 (1948); SMITH, supra, at 135–
37, likely due to the controversy surrounding those charges,
                             22
see CASSESE, supra, at 197; SMITH, supra, at 121 (reporting
that the lead French judge raised several objections to the
conspiracy charges, “[b]eginning with the obvious objection
that the crime of conspiracy was unknown to both continental
and international law”); see also TELFORD TAYLOR, FINAL
REPORT TO THE SECRETARY OF THE ARMY ON THE
NUERNBERG TRIALS UNDER CONTROL COUNCIL LAW NO. 10,
at 70 n.188, 227 (1949) (speculating that the tribunals
established in post-war Germany under Control Council Law
No. 10 rejected charges for conspiracy to commit war crimes
and crimes against humanity because of “the hostility of the
French (and probably Soviet) judges to the concept of
conspiracy” and recounting that during the proceedings under
the London Charter “many European jurists view[ed] the
Anglo-Saxon concept of criminal conspiracy with deep
suspicion”). Indeed, after returning from Nuremberg, even
Justice Jackson wrote approvingly of the “more
discriminating principles upon which to prosecute criminal
gangs, secret associations and subversive syndicates” that he
had learned of from British, French, Soviet, and German
lawyers. Krulewitch v. United States, 336 U.S. 440, 450
(1949) (Jackson, J., concurring).

     To take a more recent example, during negotiations over
the Rome Statute for the International Criminal Court, the
concept of conspiracy again presented a “very divisive issue.”
Per Saland, International Criminal Law Principles in THE
INTERNATIONAL CRIMINAL COURT: THE MAKING OF THE
ROME STATUTE 189, 199 (Roy S. Lee ed., 1999). At least one
proposal would have made conspiracy to commit any of the
other substantive crimes a punishable offense. See 2 Report of
the Preparatory Committee on the Establishment of an
International Criminal Court, U.N.GAOR, 51st Sess., Supp.
No. 22A, at 94–95, U.N. Doc. A/51/22 (1996), reprinted in
M. CHERIF BASSIOUNI, THE STATUTE OF THE INTERNATIONAL
                              23
CRIMINAL COURT: A DOCUMENTARY HISTORY 489–90 (1998).
But the final statute did not incorporate the idea. See Rome
Statute. It appears that conspiracy was ultimately excluded as
a substantive offense because of “conceptual differences
concerning conspiracy among the different legal systems” and
because of a belief among some that inchoate conspiracy
should be punishable only when its object is an “exceptionally
serious crime.” 2 Report of the Preparatory Committee, supra,
at 95; see also, e.g., Rapporteur for the Preparatory
Committee on the Establishment of an International Criminal
Court, Summary of the Proceedings of the Preparatory
Committee During the Period 25 March–12 April 1996, at
75–77, A/AC.249/1 (May 7, 1996) (reporting a Japanese
proposal to exclude punishment for conspiracy except where
it relates to “exceptionally serious offences,” for which “it
may be necessary to punish a conduct of plot or preparation
before the commencement of the execution of a crime”).

     The emphasis that international tribunals have placed on
distinguishing concepts like joint criminal enterprise as a
liability theory from the standalone crime of conspiracy
further demonstrates conspiracy’s lack of acceptance within
international law. For example, in rejecting a challenge to the
prosecution’s ability to charge a defendant with substantive
offenses like murder on a joint criminal enterprise theory of
liability—a concept discussed in greater detail below—the
Appeals Chamber for the International Criminal Tribunal for
the Former Yugoslavia stressed: “Criminal liability pursuant
to a joint criminal enterprise is not a liability for mere
membership or for conspiring to commit crimes, but a form of
liability concerned with the participation in the commission of
a crime as part of a joint criminal enterprise, a different
matter.” Prosecutor v. Milutinović, Case No. IT-99-37-AR72,
Decision on Dragoljub Ojdanić’s Motion Challenging
Jurisdiction—Joint Criminal Enterprise, ¶ 26 (Int’l Crim.
                             24
Trib. for the Former Yugoslavia, Appeals Chamber, May 21,
2003).

     In sum, conspiracy to violate the laws of war is not a
punishable offense under international law. Cf. Hamdan, 696
F.3d at 1249–51 (looking to similar sources to conclude that
material support for terrorism is not a violation of the
international laws of war). Indeed, not only has the
government conceded as much, but a plurality of the Supreme
Court has already so found. See Hamdan, 548 U.S. at 610
(plurality opinion). Accordingly, Congress cannot vest
military commissions with jurisdiction to try enemy
combatants for that offense without running afoul of
Article III.

                             C.

    With inchoate conspiracy lying beyond the reach of any
accepted understanding of the international laws of war, the
government offers a different interpretation of Quirin and
other relevant precedents. Its arguments are unpersuasive.

     First, the government insists that Quirin itself
demonstrates that the atextual Article III exception for
military trials of “law of war” offenses extends to purely
domestic war crimes. In support, it claims that “spying and
the kindred offense of sabotage”—the offenses the Court
examined in Quirin—were not, and have never been, offenses
against the international laws of war. Resp’t’s Br. 44–45; see
Kavanaugh Op. at 9–12 & nn.6–7. In its view, this shows that
the “law of war” to which the Court referred in carving out an
Article III exception includes purely domestic offenses.

    The greatest flaw in the government’s argument is that
the Court expressly identified the “law of war” as a branch of
                               25
international law. See Quirin, 317 U.S. at 29. That definition
was consistent with the widely recognized understanding of
that term. See, e.g., WINTHROP, MILITARY LAW, supra, at 773
(defining the law of war as a “branch of International Law”);
Laws of War, BLACK’S LAW DICTIONARY (3d ed. 1933)
(“This term denotes a branch of public international law, and
comprises the body of rules and principles observed by
civilized nations for the regulation of matters inherent in, or
incidental to, the conduct of a public war . . . .”). It was also
consistent with the Quirin parties’ understanding of the term.
See Brief for the United States 29, Quirin, 317 U.S. 1
(describing the “law of war” as a “centuries-old body of
largely unwritten rules and principles of international law
which governs the behavior of both soldiers and civilians
during time of war” (citing, inter alia, WINTHROP, MILITARY
LAW, supra, at 773)); Brief for Petitioners 28, Quirin, 317
U.S. 1 (“[T]he alleged Law of War which is asserted by the
prosecution is a species of international law analogous to
common law.”). Had the Court thought that the term actually
encompassed a domestic “common law of war,” it likely
would have said as much. Thus, we should apply Quirin’s
Article III exception for military trials of “law of war”
offenses as the Quirin Court defined it—that is, as an
exception for military trials of those who violate the
internationally agreed upon rules governing armed conflict.

     But the government’s argument suffers from yet another
major flaw—the Supreme Court’s analysis makes clear that it
viewed “spying and the kindred offense of sabotage” as
offenses against the international laws of war. The Court
began its analysis from the premise that Congress had
authorized the use of military commissions for “offenders or
offenses against the law of war,” Quirin, 317 U.S. at 28,
which, as noted above, the Court identified as a “branch of
international law,” id. at 29; see Part II.A, supra. Thus, when
                               26
it concluded that Congress had vested military commissions
with jurisdiction over the offense of having passed behind
enemy lines with the intent to commit espionage or sabotage,
see Quirin, 317 U.S. at 35–36, it implicitly concluded that
those offenses violated the international laws of war.

     Further to the point, in analyzing the charge, the Court
looked to “[a]uthorities on International Law” who “regarded
as war criminals” saboteurs who passed behind enemy lines
without uniform, id. at 35 n.12, and it relied on international
sources to establish that the offense was, “[b]y universal
agreement and practice,” recognized as an international law
violation, id. at 30 & n.7, 31 n.8, 35 n.12. It also quoted early
statutes and military proceedings that appeared to identify
spying as punishable by military tribunal according to the
“law and usage of nations”—that is, according to international
practice. Id. at 31 n.9, 41. Accordingly, although the
government points to scholarly criticism of the Court’s
treatment of spying, see Resp’t’s Br. 33–35, we are bound by
the Court’s own analysis, which was premised on the
understanding that spying and sabotage were international
law-of-war offenses. See Quirin, 317 U.S. at 35–36.

     The government pushes back, pointing out that Quirin
surveyed American historical practice in determining whether
the conduct described in the first charge constituted a
violation of the “law of war.” In its view, this shows that the
Court believed that the “law of war” encompassed domestic
offenses. But, once again, the Court in Quirin expressly
defined the law of war as a body of international law. Quirin,
317 U.S. at 28–29. It would have been strange for the Court to
have defined it as such if it understood that it also
encompassed a domestic body of law. Considered in its
proper context, then, Quirin’s analysis of domestic precedents
for trying spying and sabotage reflect an effort to confirm that
                               27
our law did not preclude a military trial for the specified
offense. That is, the Court referred to U.S. cases to discern
potential domestic limits on the prosecution of law-of-war
offenses. The Court explained that there might be offenses
that

    would not be triable by military tribunal here, either
    because they are not recognized by our courts as
    violations of the law of war or because they are of that
    class of offenses constitutionally triable only by a jury.

Id. at 29; see id. (citing, as an example of the latter, Ex parte
Milligan, 71 U.S. (4 Wall.) 2). The government’s position
gains no support from Hamdan’s consideration of domestic
precedents in determining whether inchoate conspiracy
qualified as a violation of the “law of war,” as that term is
used in 10 U.S.C. § 821. The plurality looked to domestic
precedent in just the same way the Quirin Court had: as a
potential limitation on military-commission jurisdiction. See
Hamdan, 548 U.S. at 603, 610 (plurality opinion); Al
Bahlul II, 792 F.3d at 8–9; id. at 25–26 (Tatel, J., concurring).

     The government next argues that Article III must be
construed in light of Congress’s Article I powers and that
those powers enable Congress to go beyond international law
in determining the offenses triable by military commission. In
support, the government notes that Quirin and its progeny
indicate that Congress’s power to create military commissions
derives from its war powers. Resp’t’s Br. 29–30 (citing, inter
alia, Yamashita, 327 U.S. at 11). It then argues that
Congress’s power to codify offenses triable by such tribunals
must stem from those powers as well. Those powers include
the power to “declare War,” U.S. CONST. art. I, § 8, cl. 11,
“raise and support Armies,” id. § 8, cl. 12, “provide and
maintain a Navy,” id. § 8, cl. 13, “make Rules for the
                               28
Government and Regulation of the land and naval Forces,” id.
§ 8, cl. 14, and “provide for calling forth the Militia,” id. § 8,
cl. 15. Pointing out that these powers, unlike the define and
punish power, contain no textual limitation based on
international law, the government concludes that Congress’s
power to define offenses triable by military commissions must
be similarly unconstrained. See Resp’t’s Br. 30–32; see also
Kavanaugh Op. at 4–19.

     As an initial matter, although it is true that Quirin,
Yamashita, and Hamdan looked to the war powers in
discussing congressional authority to establish military
commissions, see Hamdan, 548 U.S. at 591 (plurality
opinion); Yamashita, 327 U.S. at 12; Quirin, 317 U.S. at 26;
see also WINTHROP, supra, at 831 (stating that Congress’s
power “to ‘declare war’ and ‘raise armies’” provided the
“original sanction” for military commissions), they
consistently looked to the Define and Punish Clause alone in
addressing Congress’s authority to confer jurisdiction over
particular offenses. See Hamdan, 548 U.S. at 601–02
(plurality opinion); Yamashita, 327 U.S. at 7; id. at 26
(Murphy, J., dissenting); Quirin, 317 U.S. at 28. For instance,
in Yamashita, the Court explained that “the [military]
commission derives its existence” from the war powers, 327
U.S. at 12 (emphasis added), but that its jurisdiction over
specific offenses comes from Congress’s “exercise of the
power conferred upon it by Article I, § 8, cl. 10 of the
Constitution to ‘define and punish * * * Offenses against the
Law of Nations * * *,’ of which the law of war is a part.” Id.
at 7 (alteration in original). Winthrop endorsed this
distinction, stating that Civil War-era legislation subjecting
“spies and guerillas” to military jurisdiction “may be regarded
as deriving its authority from” the Define and Punish Clause.
WINTHROP, supra, at 831.
                              29
     The government argues that it would be “anomalous”—
and three of our colleagues call it “absurd”—to conclude that
the war powers authorize Congress to establish military
commissions but not vest them with jurisdiction over specific
offenses. See Resp’t’s Br. 31; Kavanaugh Op. at 7 n.5. But as
noted above, the Supreme Court has repeatedly drawn this
precise distinction. Thus, even were we to determine the
scope of the Article III exception by reference to Congress’s
Article I powers, it would still be constrained by international
law.

     Despite Quirin’s discussion of Congress’s Article I
powers in determining whether the President and Congress
had the authority to establish military commissions, Quirin
did not look to Congress’s Article I powers in determining the
scope of the Article III exception. See Quirin, 317 U.S. at 39–
41. Rather, it looked to historical practice regarding military
commissions at the time that the Constitution was adopted to
conclude that Article III posed no bar to military trials of
enemy combatants who violate the laws of war. Id.

     The government next argues that Congress may define
conspiracy to commit war crimes as a law-of-war offense by
virtue of its power to define and punish offenses against the
“Law of Nations.” See Resp’t’s Br. 55; see also Millett Op. at
38–39. In support, it claims that international law includes
sufficiently analogous notions of criminal liability. Resp’t’s
Br. 3.

     But, as the government admits, “[w]hen conspiracy is
used as a mode of liability under international law, there is
generally a requirement that the object offense be completed
or attempted.” Resp’t’s Br. 56. The military commission in al
Bahlul’s case was instructed that it could convict him of
conspiracy without “[p]roof that the offense[s]” that were the
                              30
objects of the conspiracy—murder, attacking civilians or
objects, murder and destruction of property in violation of the
law of war, terrorism, and providing material support for
terrorism—“actually occurred.” Trial Tr. 848. Neither, under
these instructions, did al Bahlul’s overt act in furtherance of
the conspiracy have to be a criminal act; as an element of
proof of a standalone conspiracy charge, the overt act serves
merely as “a clear indication that the conspiracy is being
carried out.” Id. at 849.

     The government also points to prosecutions for
conspiracy brought under the domestic laws of individual
allied governments following World War II, see Resp’t’s Br.
55, but those prosecutions are irrelevant to whether
conspiracy was a punishable offense against international law.
Many offenses that are punished by many, if not all, countries
are not of concern to international law because “international
law addresses only those ‘wrong[s]’ that are ‘of mutual, and
not merely several, concern’ to States.” Flores v. Southern
Peru Copper Corp., 414 F.3d 233, 249 (2d Cir. 2003)
(quoting Filartiga v. Pena-Irala, 630 F.2d 876, 888 (2d Cir.
1980)); see also United States v. Bellaizac-Hurtado, 700 F.3d
1245, 1252 (11th Cir. 2012).

     To be sure, when Congress legislates for the punishment
of war crimes outside of Article III courts, it may have
authority to clarify somewhat murky areas of international
law. See U.S. CONST. art. I, § 8, cl. 10. But Congress certainly
has no power to make up that law entirely. See, e.g., Military
Commissions, 11 Op. Att’y Gen. 297, 299 (1865) (“To define
is to give the limits or precise meaning of a word or thing in
being; to make is to call into being. Congress has power to
define, not to make, the laws of nations . . . .”) (second
emphasis added); see also 2 THE RECORDS OF THE FEDERAL
CONVENTION OF 1787, at 615 (Max Farrand ed., rev. ed. 1937)
                              31
(Statement of Gouverneur Morris); Bellaizac-Hurtado, 700
F.3d at 1250 (“The insertion of the power to “define” enabled
Congress to provide notice to the people through codification;
it did not enable Congress to create offenses that were not
recognized by the law of nations.”); cf. United States v.
Furlong, 18 U.S. (5 Wheat.) 184, 198 (1820) (when
exercising its power to define and punish piracy, Congress
cannot redefine that offense). Indeed, in clear contrast to
Congress’s authority to “make Rules for the Government and
Regulation of the land and naval Forces,” U.S. CONST. art. I,
§ 8, cl. 14 (emphasis added), Congress has the authority only
to “define” offenses against the law of nations. See also NOAH
WEBSTER, 1 A COMPENDIOUS DICTIONARY OF THE ENGLISH
LANGUAGE 79 (1806) (“define” means “to explain, limit,
mark out, fix, decide”); SAMUEL JOHNSON, 1 A DICTIONARY
OF THE ENGLISH LANGUAGE, at dlvii (6th ed. 1785) (“define”
means “to give definition, to explain a thing by its qualities
and circumstances”; or “to circumscribe, to mark the limit, to
bound”).

     Here, as the government asserts, Congress in the Military
Commissions Act of 2006 has done much more than codify an
accepted but not fully defined concept of international law; it
has made a new war crime, one that the international
community has repeatedly declined to adopt. See Part II.B,
supra. Whether Congress might be entitled to the type of
leeway the government suggests when it exercises its define
and punish powers to legislate for the punishment of crimes in
Article III courts, it did no such thing in the Military
Commissions Act. That Act legislated for the punishment of
crimes in military commissions. In doing so, it ran up against
a clear constitutional limit: Article III’s commitment of the
“judicial Power” to the Supreme Court and “such inferior
Courts as Congress may from time to time ordain and
establish.” U.S. CONST. art. III, § 1.
                               32

       The government also invokes the Necessary and Proper
Clause, U.S. CONST. art. I, § 8, cl. 18, which authorizes
Congress to “make all Laws which shall be necessary and
proper for carrying into Execution the foregoing Powers.”
The government argues that Congress may enact legislation
necessary to comply with the nation’s “international
responsibilities,” and that Congress was reasonably seeking to
fulfill its obligation to prevent acts of terrorism and war
crimes when it made conspiracy punishable by military
commission. Resp’t’s Br. 58. It points to the nation’s
responsibilities under the Geneva Convention Relative to the
Protection of Civilian Persons in Time of War, supra, 6
U.S.T. 3516, 75 U.N.T.S. 287, which prohibits “[c]ollective
penalties and likewise all measures of intimidation or of
terrorism.” Id. art. 33. The Convention requires signatories to
“undertake to enact any legislation necessary to provide
effective penal sanctions for persons committing, or ordering
to be committed, any of the grave breaches of the present
Convention,” id. art. 146, which include the “willful killing
. . . of a protected person,” id. art. 147, defined as “those who
. . . find themselves, in case of a conflict or occupation, in the
hands of a Party to the conflict or Occupying Power of which
they are not nationals,” id. art. 4.

     But the Necessary and Proper Clause does not allow
Congress to do what it is otherwise expressly barred from
doing. See United States ex rel. Toth v. Quarles, 350 U.S. 11,
21–22 (1955). And however it may affect Congress’s define
and punish power when it legislates for the punishment of
international offenses in Article III courts, the Necessary and
Proper Clause cannot be read to allow Congress to do an end
run around the constitutional limit imposed by Article III. See
id. at 22; Reid, 354 U.S. at 22 (plurality opinion); see also
Northern Pipeline, 458 U.S. at 73 (plurality opinion)
                              33
(“[W]here Art. III does apply, all of the legislative powers
specified in Art. I and elsewhere are subject to it.”).

     Article III’s limitations on congressional power apply
even where Congress exercises its powers to enact
“legislation necessary to carry out its international obligation
to prevent terrorism as a mode of warfare.” Resp’t’s Br. 57.
The political branches’ efforts to comply with international
obligations must also comply with the Constitution. See
Medellin v. Texas, 552 U.S. 491, 520 (2008); Reid, 354 U.S.
at 16 (plurality opinion). Even assuming that Congress could
only meet its international obligations by criminalizing
conduct not recognized as an offense against international
law, the government never explains why its asserted authority
to do so under Article I would imply the power to establish
military jurisdiction over that conduct. See United States v.
Arjona, 120 U.S. 479, 484 (1887).

     Ultimately, whether Congress’s authority to codify the
offenses triable by military commissions is grounded in its
define and punish powers or its war powers is beside the
point. So too is the Necessary and Proper Clause’s impact on
Congress’s Article I authority to comply with its international
obligations by going somewhat beyond the current scope of
international law. Whichever clause in Article I, § 8 grants
Congress the authority to establish and determine the offenses
triable by military commissions, and whatever the impact of
the Necessary and Proper Clause on Congress’s Article I
powers, Congress may not transgress the bounds of Article
III. Article III does include an exception for law-of-war
military commissions. But that has been narrowly defined by
reference to the international laws and customs governing
war. Quirin, 317 U.S. at 38–41.
                               34
                               D.

     The government last falls back on the idea that
Article III’s scope must be determined by reference to
historical practice. This argument comes in two forms. First,
the government maintains that spying and aiding the enemy
are not violations of the international laws of war but that
Congress has made those offenses triable by military
commission since the early days of the Republic. This, its
argument continues, shows that early congresses believed
Article III poses no bar to making domestic crimes punishable
by military commission. Second, the government maintains
that “the experience of our wars and the acts and orders of our
wartime tribunals reflect a long history of trying conspiracy to
violate the laws of war in a military commission,” Resp’t’s
Br. 2–3; see Kavanaugh Op. at 14–19, 21, and that Article III
must be considered in light of that practice. Neither argument
advances the government’s cause.

     With respect to the first, it is true that Congress has long
made spying and aiding the enemy punishable by military
commission. See, e.g., An Act for Establishing Rules and
Articles for the Government of the Armies of the United
States, § 2, 2 Stat. 359, 371 (1806) (Articles of War). But the
government’s reliance on early congressional statutes making
spying and aiding the enemy punishable by military
commission suffers from two flaws. First, the government
cites nothing indicating early congresses actually knew that
those two offenses did not violate the international laws of
war, and some sources suggest they might well have believed
that those offenses did. For instance, an 1806 statute
“imposed the death penalty on alien spies ‘according to the
law and usage of nations, by sentence of a general court
martial.’” Quirin, 317 U.S. at 41 (quoting Act of Congress of
Apr. 10, 1806, 2 Stat. 359, 371). A 1776 Resolution adopted
                               35
by the Continental Congress contained a nearly identical
provision. See Resolution of Aug. 21, 1776, 5 JOURNALS OF
THE CONTINENTAL CONGRESS 693 (Ford ed. 1906). In 1865,
the Attorney General of the United States, James Speed, also
concluded in a formal opinion that “every lawyer knows that a
spy was a well-known offender under the laws of war, and
that under and according to those laws he could have been
tried and punished without an act of Congress.” 11 Op. Att’y
Gen. at 312, 313. Thus, we cannot infer from those early
statutes that early congresses understood Article III to pose no
bar to the punishment of domestic war crimes in military
tribunals.

     But even were there evidence that early congresses
understood that spying and aiding the enemy were not
international law-of-war offenses, it would shed little light on
whether early congresses felt free to punish purely domestic
offenses as they saw fit. Both spying and aiding the enemy
have been subject to military jurisdiction since the ratification
of the Constitution. See Quirin, 317 U.S. at 41; Resolution of
Aug. 21, 1776, 5 JOURNALS OF THE CONTINENTAL CONGRESS
693 (Ford ed. 1906) (“[A]ll persons, not members of, nor
owing allegiance to, any of the United States of
America . . . who shall be found lurking as spies . . . shall
suffer death, according to the law and usage of nations, by
sentence of a court martial . . . .”); Resolution of Sept. 20,
1776, 5 JOURNALS OF THE CONTINENTAL CONGRESS 799 (Ford
ed. 1906) (“Whosoever shall relieve the enemy with money,
victuals, or ammunition, or shall knowingly harbour or protect
an enemy, shall suffer death, or such other punishment as by a
court-martial shall be inflicted.”); Act of Apr. 10, 1806, 2
Stat. 371. As a result, those two offenses may well fit within
an established historical exception.
                               36
     Indeed, although the government and four of our
colleagues contend that Congress’s longstanding practice of
making spying and aiding the enemy triable by military
tribunal “strongly supports the conclusion that international
law is not a constitutional constraint on Congress’s authority
to make particular crimes triable by military commission,”
Kavanaugh Op. at 12; see Resp’t’s Br. 32–33; Henderson Op.
at 1, incorporating by reference Al Bahlul II, 792 F.3d at 69
(Henderson, J., dissenting), it seems that, if anything,
Congress’s consistent decision to codify those two offenses—
and those two offenses alone—undermines that conclusion.
Had Congress, over the last two hundred years, actually
believed itself free to punish by military tribunal whatever
wartime conduct it deemed necessary, it would be rather
surprising that it codified only two offenses, both of which
were subject to military trial at the time the Constitution was
adopted. Thus, while these two offenses may fall within an
Article III exception based on longstanding historical practice,
we find them uninformative regarding Congress’s general
authority to make purely domestic crimes punishable by
military commission.

    This brings us to the government’s final contention that
conspiracy has long been tried by military commission in the
United States and that it must therefore fall within a historical
exception to Article III. Here, too, it falters.

     Importantly, when the Supreme Court has relied on
historical practice to determine where one branch’s powers
end and another’s begin, it has required robust evidence of a
historical practice. For instance, in Myers v. United States,
272 U.S. 52, 175 (1926), in examining the President’s
removal power, the Court found more than seven decades in
which Presidents had a continuous practice of removing
executive branch officers without congressional involvement,
                              37
and on that basis held Congress lacked authority to restrict the
President’s removal power. In United States v. Curtiss-Wright
Export Corp., 299 U.S. 304, 322 (1936), the Court pointed to
an “unbroken legislative practice which has prevailed almost
from the inception of the national government to the present
day” to reject a constitutional nondelegation challenge to a
joint resolution of Congress authorizing the President to
determine whether to embargo the sale of arms and munitions
to belligerents in a foreign war. Recently, in National Labor
Relations Board v. Noel Canning, 134 S. Ct. 2550 (2014), the
Court invoked a lengthy and dense historical practice defining
the scope of the President’s authority under the Recess
Appointments Clause, U.S. CONST. art. II, § 2, cl. 3. Upon
identifying “thousands of intra-session recess appointments”
and noting that “Presidents since Madison have made many
recess appointments filling vacancies that initially occurred
prior to a recess,” id. at 2562, 2571, the Court concluded that
the Clause authorized such appointments. By contrast, where
the Court found only a handful of instances in which a
President had made a recess appointment during an inter-
session recess lasting less than ten days, the Court held that
those recesses were “presumptively too short to fall within the
Clause.” Id. at 2567.

     There is no such robust history of trying inchoate
conspiracy before law-of-war military commissions. See
Hamdan, 548 U.S. at 604 (plurality opinion). The government
has identified only a handful of at best ambiguous examples,
see Resp’t’s Br. 40–43, and none in which a conviction was
for inchoate conspiracy by a law-of-war commission that was
affirmed by the Judicial Branch. The examples are
unpersuasive in themselves and insufficient to establish a
longstanding historical practice that would justify a more
expansive understanding of the law-of-war military
commission exception to Article III.
                              38

     First, the government places substantial reliance on Civil
War era historical practice, but that practice does not support
its case. For instance, although the charges against the
Lincoln assassins referred to conspiracy, the specifications
listed the elements of the completed offense—“traitorously”
murdering President Lincoln. See J. Holt & T. Ewing,
CHARGE AND SPECIFICATION AGAINST DAVID E. HEROLD, ET
AL. 3 (1865); see also Hamdan, 548 U.S. at 604 n.35
(plurality opinion); id. at 609; General Court-Martial Orders
No. 356, War Dep’t (July 5, 1865), reprinted in H.R. Doc.
No. 55-314, at 696 (1899). The Attorney General’s formal
opinion in 1865 also described the charge as “the offence of
having assassinated the President.” 11 Op. Att’y Gen. at 297;
see id. at 316–17. As such, it appears that conspiracy was at
most a theory of liability on which to hold each of the
partners to account for the assassination completed by Booth
alone.

     Construing the Lincoln assassins’ case as a conspiracy
conviction is anachronistic and conflates conspiracy as a
theory of liability with inchoate conspiracy as a standalone
offense. See Kavanaugh Op. at 15–16. Prosecution of
conspiracy as a standalone offense, chargeable apart from and
in addition to the crimes that are the conspiracy’s object and
carrying their same penalties, is a modern innovation. See
Iannelli v. United States, 420 U.S. 770, 781 & n.13 (1975)
(citing Hampton L. Carson, The Law of Criminal
Conspiracies and Agreements as Found in the American
Cases, in R. WRIGHT, THE LAW OF CRIMINAL CONSPIRACIES
AND AGREEMENTS 191 (1887)). At the time of the Lincoln
assassination, it was unclear that conspiracy could even be
charged separately from its object offense, once completed.
See id. And when Congress first codified conspiracy as a
crime in 1867, it carried only a two-year penalty. See Act of
                              39
Mar. 2, 1867, 14 Stat. 471, 484. Conspiracy as then
understood would hardly have been an appropriate principal
charge against the President’s assassins. The government
mistakenly reads our modern understanding of conspiracy
into events, including the Lincoln assassins’ conviction, from
an era in which that understanding had not yet taken hold, a
move that fundamentally miscasts that earlier precedent.

     Further, Winthrop noted that the Lincoln assassins’
tribunal was a mixed martial-law and law-of-war military
commission. See WINTHROP, MILITARY LAW, supra, at 839 &
n.5; cf. id. at 842. The unreported district court opinion in Ex
parte Mudd, 17 F. Cas. 954 (1868), see Kavanaugh Op. at
15–16, does not undermine that conclusion; the district court
described the offense as “assassination” of the Commander in
Chief and only used “conspiracy” in the same terms as the
charging document, while distinguishing Ex parte Milligan
based on the state of war in the Capital, not based on the
nature of the offense. Ex parte Mudd, 17 F. Cas. at 954. Thus,
“even if [it could be] properly classified as a trial by law-of-
war commission, [the Lincoln assassins’ trial] is at best an
equivocal exception.” Hamdan, 548 U.S. at 604 n.35
(plurality opinion) (internal citation omitted); see also Al
Bahlul II, 792 F.3d at 12.

     Second, the government asserts that other Civil War
precedents show that defendants were charged with
conspiracies as unconsummated offenses. Resp’t’s Br. 42–43.
The examples on which it relies do not support its position.
Col. George St. Leger Grenfel was convicted by a military
tribunal of conspiracy to free prisoners of war in Chicago and
to destroy that city. See GENERAL COURT MARTIAL ORDERS
No. 452, War Dep’t (Aug. 22, 1865), reprinted in H.R. Doc.
No. 55-314, at 724–35. As al Bahlul points out, Grenfel’s
commission, like that of the Lincoln assassins, was a
                              40
“hybrid” commission exercising jurisdiction based in part on
the President’s declaration of martial law. See Reply Br. 20
(citing Hamdan, 548 U.S. at 609 n.37 (plurality opinion);
WINTHROP, MILITARY LAW, supra, at 839 n.5); S. STARR,
COLONEL GRENFEL’S WARS: THE LIFE OF A SOLDIER OF
FORTUNE, 5, 219 (1971) (cited in Resp’t’s Br. 41). Such
hybrid commissions “regularly tried war crimes and ordinary
crimes together,” Hamdan, 548 U.S. at 608, and the crimes
charged were, “‘[n]ot unfrequently[,] . . . a combination of
the two species of offenses’”—that is, hybrid versions of law-
of-war offenses and domestic crimes, id. (quoting C.
HOWLAND, A DIGEST OF OPINIONS OF THE JUDGE ADVOCATES
GENERAL OF THE ARMY 1071 (1912)). These cases thus
provide little insight into the traditional jurisdiction of pure
law-of-war military commissions. Indeed, in defending the
jurisdiction of the Grenfel commission, the prosecution relied
on the fact that “martial law obtained throughout the United
States and the Territories during the continuance of the
[Civil] [W]ar.” Judge Advocate’s Reply, Courtroom,
Cincinnati, Ohio, Jan. 17, 1865, United States v. Walsh, et al.,
reprinted in H. EXEC. DOC. NO. 50, 39th Cong., 2d Sess., at
20. The Grenfel commission, like the Lincoln assassins’
commission, “is at best an equivocal” example. Hamdan, 548
U.S. at 604 n.35 (plurality opinion).

    The government’s reliance on the case of Confederate
Army Captain Henry Wirz is similarly misplaced; in his case
conspiracy served only as a mode of liability for the
completed law-of-war offenses of abusing, torturing, and
murdering war prisoners. GENERAL COURT MARTIAL
ORDERS, No. 607, War Dep’t (Nov. 6, 1865), reprinted in
H.R. Doc. No. 55-314, at 785, 789.

    Also unavailing are the government’s citations to
William Winthrop’s 1880 Digest of Opinions of the Judge
                               41
Advocate General of the Army and to Charles Roscoe
Howland’s 1912 Digest of Opinions of the Judge Advocate
General of the Army. Both stated that, during the Civil War,
one of the principal offenses charged in military commissions
as an offense against the laws of war was “[c]onspiracy by
two or more to violate the laws of war by destroying life or
property in aid of the enemy.” W. WINTHROP, A DIGEST OF
OPINIONS OF THE JUDGE ADVOCATE GENERAL OF THE ARMY
329 (1880); HOWLAND, supra, at 1071. But a Supreme Court
plurality has already examined the cases cited and concluded
that they provide “no support for the inclusion of conspiracy
as a violation of the law of war.” Hamdan, 548 U.S. at 607
(plurality opinion). And, as that plurality further noted,
Winthrop’s subsequent treatise, Military Law and Precedents,
does not list conspiracy as an offense against the laws of war.
Id. at 608 (citing WINTHROP, MILITARY LAW, supra, at 839–
40).

     Indeed, in his later treatise, Winthrop clarified the issue.
In describing the mixed jurisdiction of military commissions
during the Civil War, he noted that the tribunals presided over
two classes of offenses—“(1) Crimes and statutory offenses
cognizable by State or U.S. courts, and which would properly
be tried by such courts if open and acting; [and] (2) Violations
of the laws and usages of war cognizable by military tribunals
only.” WINTHROP, MILITARY LAW, supra, at 839. He
identified criminal conspiracy as a crime of the first class, but
made no mention of conspiracy in the second. In a footnote,
he also identified many of the conspiracy cases to which the
government now points, including those of Wirz, Grenfel, and
the Lincoln assassins, as having been of the first class (i.e.,
cases charging crimes normally triable only in civil court) or
“of the first and second classes combined,” id. at 839 n.5, that
is, cases charging “species of compound offense[s] of the type
tried by the hybrid military commissions of the Civil War,”
                               42
Hamdan, 548 U.S. at 608 (plurality opinion). Those cases
thus fail to support the government’s contention that there is a
robust history of trying conspiracy in pure law-of-war military
commissions.

     Third, the government draws on World War II-era
practice. Although the charges against the Nazi saboteurs in
Quirin included conspiracy, the Supreme Court upheld the
jurisdiction of the law-of-war military commission only as to
the charge of passing behind enemy lines with hostile
purpose and did not mention conspiracy in its analysis. See
Quirin, 317 U.S. at 46. Similarly, although William
Colepaugh was convicted of sabotage and spying, in addition
to conspiracy to commit those offenses, the U.S. Court of
Appeals for the Tenth Circuit affirmed the jurisdiction of the
military tribunal in view of the law-of-war offense of
unlawful belligerency only, without addressing the
conspiracy charge. See Colepaugh v. Looney, 235 F.2d 429,
431–32 (10th Cir. 1956).

     The government insists that these cases are nonetheless
important because “despite such judicial review, ‘no U.S.
court has ever cast any doubt on the landmark military
commission convictions embracing conspiracy charges, or the
validity of trying conspiracy by military commission.’”
Resp’t’s Br. 37–38 (quoting Al Bahlul I, 767 F.3d at 70
(Kavanaugh, J., concurring in the judgment in part and
dissenting in part)) (alterations omitted). To this, it adds that
executive branch officials, including the President, approved
the charges in both cases, thereby giving their “imprimatur” to
the convictions. Id. at 38.

     But at most those cases underscore the uncertain position
that the crime of conspiracy has occupied in the history of
military commissions. The defendants in both Quirin and
                              43
Colepaugh challenged the conspiracy charges on the ground
that the military commissions lacked jurisdiction over that
offense, see Brief for Petitioner at 29, Quirin, 317 U.S. 1;
Opinion of Special Board of Review, United States v.
Colepaugh, CM 276026, at 28 (Mar. 27, 1945), suggesting
that it was in no sense well established that military tribunals
had jurisdiction to preside over conspiracy charges.
Additionally, the court in each case focused on completed
violations of the international laws of war and declined to
address the legitimacy of the conspiracy charges, indicating
that those charges may have presented difficult questions. In
Hamdan, four Justices recognized as much, stating:

   If anything, Quirin supports Hamdan’s argument that
   conspiracy is not a violation of the law of war. Not
   only did the Court pointedly omit any discussion of
   the conspiracy charge, but its analysis of Charge I
   placed special emphasis on the completion of an
   offense; it took seriously the saboteurs’ argument that
   there can be no violation of the law of war—at least
   not one triable by military commission—without the
   actual commission of or attempt to commit a hostile
   and warlike act.

548 U.S. at 606–07 (plurality opinion) (internal quotation
marks omitted)). Thus, these cases appear neutral at best and,
more likely, undermine the government’s position.

     The government also relies on evidence that the
executive branch has viewed conspiracy as triable by military
commission, suggesting that this is entitled to some weight.
Resp’t’s Br. at 34–46; see Kavanaugh Op. at 14–18. But the
executive branch opinions on which it relies rest on shaky
foundations. For example, although Assistant Attorney
General Tom Clark concluded in a memorandum that
                             44
William C. Colepaugh could be tried for conspiracy in a law-
of-war military commission, the sources on which he relied
drew almost exclusively from martial-law commissions that
exercised plenary jurisdiction, not law-of-war military
commissions of the kind at issue here. See Memorandum
from Tom C. Clark, Assistant Attorney General, to Myron C.
Kramer, Judge Advocate General (Mar. 12, 1945), reprinted
in Government Supplemental Appendix 104–10 (citing, inter
alia, the Lincoln Assassins and Captain Wirz).

      The orders of General MacArthur from the Korean
Conflict, see Resp’t’s Br. 39; Millet Op. at 41, also offer
little, if any, support for the government because the en banc
court has viewed such military orders as unpersuasive for
lack of high-level Executive Branch consultation. See Al
Bahlul I, 767 F.3d at 25 n.16. And during the Korean Conflict
there apparently were no prosecutions conducted by United
Nations Military Commissions. See JORDAN J. PAUST ET AL.,
INTERNATIONAL CRIMINAL LAW: CASES AND MATERIALS 724
(1996).

     In sum, the Supreme Court has recognized a limited
Article III exception for the prosecution of internationally
recognized war crimes in military tribunals. The government
has offered no reason—rooted in history, the Constitution,
case law, or anything else—for extending that exception
further.

                             III.

     We turn now to the additional arguments of our
colleagues.
                              45
                              A.

     Four of our colleagues believe that Hamdan supports the
notion that Congress can vest law-of-war military
commissions with jurisdiction over inchoate conspiracy
without transgressing the bounds of Article III because
several Justices in Hamdan “expressly invited Congress to
clarify the scope of military commission power” without
“even hint[ing] at a lurking constitutional problem with trying
conspiracy offenses before military commissions.”
Kavanaugh Op. at 26; see also Henderson Op. at 1,
incorporating by reference Al Bahlul II, 792 F.3d at 50-52
(Henderson, J., dissenting); Resp’t’s Br. 53.

     The Justices’ invitation to Congress in Hamdan is,
however, a thin reed on which to rest. For one thing, it is far
from clear that the invitation was in any way related to
Congress’s ability to make inchoate conspiracy punishable by
military commission. Hamdan’s principal holding was that
the commissions convened under Military Commission Order
No. 1, such as Salim Hamdan’s, were invalid because their
procedures failed to comport with statutory requirements. 548
U.S. at 613. The Justices’ may have thus intended their
“invitation” to underscore nothing more than Congress’s
power to authorize the invalidated procedures. See id. at 636
(Breyer, J., concurring) (“Congress has denied the President
the legislative authority to create military commissions of the
kind at issue here. Nothing prevents the President from
returning to Congress to seek the authority he believes
necessary.”).

   Perhaps equally important, the issues presented in
Hamdan did not include the question we consider here, i.e.,
whether Article III limits Congress’s authority to vest military
commissions with jurisdiction over conspiracy charges. The
                               46
two questions on which the Supreme Court granted certiorari
asked: (1) whether the President required congressional
authorization to establish law-of-war military commissions
and, if so, whether the President had received such
authorization; and (2) whether Guantanamo detainees could
enforce the provisions of the 1949 Geneva Conventions in
habeas corpus proceedings. Although the parties’ briefs in
Hamdan touched on related issues, neither side squarely
addressed Article III’s limits on military-commission
jurisdiction. This court should, accordingly, not read too
much into the Justices’ invitation.

     Next, Judge Kavanaugh, like the government, believes
that Congress derives its authority to determine the offenses
triable by military commission from its war powers and that
those powers are unconstrained by international law. In his
view, the Constitution cannot possibly give the international
community—through the development of international law—
the ability to limit Congress’s exercise of its war powers.
Kavanaugh Op. at 8–9. It is not international law, however,
that constrains Congress’s authority here—it is Article III.
The Framers of the Constitution expected Article III courts to
have jurisdiction over the trial of all crimes, Toth, 350 U.S. at
15; Reid, 354 U.S. at 21 (plurality opinion), save for a few
narrow exceptions, such as battlefield prosecutions of enemy
combatants who “in their attempt to thwart or impede our
military effort have violated the law of war,” Quirin, 317 U.S.
at 28–29; id. at 41–42. The international-law constraint that
Quirin recognized and that we would apply here functions not
as an independent constraint on the political branches’ powers
to wage war, but rather as an essential demarcation between
military and civilian jurisdiction. Without it, “the line between
civilian and military jurisdiction could become elusive—if not
altogether illusory.” National Institute of Military Justice
Amicus Br. 29. We find apt here the Supreme Court’s
                               47
warning in Northern Pipeline, 458 U.S. at 73–74 (plurality
opinion), against constitutional interpretations that would
“replace the principles delineated in [Supreme Court]
precedents, rooted in history and the Constitution, with a rule
of broad legislative discretion that could effectively eviscerate
the constitutional guarantee of an independent Judicial Branch
of the Federal Government.”

     The idea that international law has a role to play in our
constitutional framework is also not as surprising as one
might think. The Framers of the Constitution well understood
that our country’s newly forged sovereignty brought with it
both rights and obligations. John Jay, the first Chief Justice of
the United States, explained in 1793 that the United States
“had, by taking a place among the nations of the earth,
become amenable to the laws of nations.” Chisholm v.
Georgia, 2 U.S. (2 Dall.) 419, 474 (1793) (opinion of Jay,
C.J.). Embracing the law of nations and adhering to its
principles, he further explained, was the new nation’s “duty”
and in its own “interest.” Id.; see also Who Privileged from
Arrest, 1 Op. Att’y Gen. 26, 27 (1792) (The law of nations’
“obligation commences and runs with the existence of a
nation.”).

     There is nothing anomalous or contrary to national
security in vesting Article III courts with exclusive power to
try all crimes except for internationally recognized war crimes
that have been traditionally tried by military commission. Our
military has long abided by the international laws of war. For
instance, in its 1940 Rules of Land War, it noted that the
“well-established rules known as the rules or laws of war”
that govern the conduct of war among civilized nations “are
binding upon all civilized nations,” and are to “be strictly
observed by our forces.” War Department, Rules of Land
Warfare 1–2 (1940). Both the Framers’ and our military’s
                              48
desire to adhere to the law of nations and, more specifically,
the laws of war appears sound: “If the United States now
decides that it can hold foreign personnel accountable for
violating ‘national’ law-of-war rules, other states will be
entitled to assert the same authority.” Glazier Amicus Br. 27;
see Arjona, 120 U.S. at 487 (“[W]hat is law for one is, under
the same circumstances, law for the other.”).

     Standing firm on the constitutionally prescribed
boundaries between civilian and military jurisdiction is
compelled by Supreme Court precedent and doubly
compelled where, as here, the government has made no claim
of military necessity. Military exigency, although insufficient
to justify military jurisdiction, is nevertheless a necessary
condition. Hamdan, 548 U.S. at 590. But remarkably,
throughout this protracted litigation, the government has
offered no reason to believe that expanding the traditionally
understood scope of Article III’s exception for law-of-war
military commissions is necessary to meet a military
exigency. We claim no authority to determine military
necessity; we simply note that the government has asserted no
such exigency here. Perhaps the government has eschewed a
claim of military necessity because of the many other tools at
its disposal. Congress remains free to enact, and the President
to employ, domestic laws to bring terrorists to justice before
Article III courts, as they have on hundreds of occasions
already with remarkable success. See Al Bahlul II, 792 F.3d at
27 (Tatel, J., concurring); Center on Law and Security, New
York University School of Law, Terrorist Trial Report Card:
September 11, 2001–September 11, 2011, at 2, 7, tbl.1,
available at http://goo.gl/Ks3Okc (reporting that in the ten
years after September 11, 2001, federal prosecutors had
obtained convictions in almost 200 “jihadist-related”
terrorism and national security cases); Press Release,
Department of Justice, Fact Sheet: Prosecuting and Detaining
                               49
Terror Suspects in the U.S. Criminal Justice System (June 9,
2009) (citing Richard B. Zabel & James L. Benjamin, Jr.,
Human Rights First, In Pursuit of Justice: Prosecuting
Terrorism Cases in the Federal Courts 23 (May 2008),
available      at    http://www.humanrightsfirst.org/resource/
pursuit-justice); see also, e.g., Nizar Trabelsi, No. 15-3075
(D.C. Cir., argued May 17, 2016); United States v. Ghailani,
733 F.3d 29 (2d Cir. 2013).

     For detainees ill-suited for prosecution in Article III
courts, the government has other options. It may detain them
as enemy belligerents. See Hamdi v. Rumsfeld, 542 U.S. 507,
518–24 (2004) (plurality opinion). It may continue to try
violations of the laws of war in military commissions. See,
e.g., Government Response to Defense Motion to Dismiss for
Lack of Jurisdiction, AE107A, at 1, United States v.
Mohammad (M.C. Jan. 16, 2013) (acquiescing to Khalid
Shaikh Mohammad’s and his codefendants’ motion to dismiss
charges for inchoate conspiracy, but continuing to pursue
charges of recognized law-of-war offenses, including
attacking civilians on September 11, 2001). It might also help
craft new international conventions to address the demands of
new kinds of war and implement appropriate procedures for
prisoners of war. See generally Hamdan, 548 U.S. at 619.

     On this note, it is worth remembering that, historically,
the military has not been in the business of prosecuting
individuals for crimes and locking them up for life. Its
primary mission has always been to defeat our enemies on the
battlefield. Cf. Reid, 354 U.S. at 35 (plurality opinion) (“[T]he
business of soldiers is to fight and prepare to fight wars, not to
try civilians for their alleged crimes.”); Toth, 350 U.S. at 17
(“Unlike courts, it is the primary business of armies and
navies to fight or be ready to fight wars should the occasion
arise. . . . [T]rial of soldiers to maintain discipline is merely
                               50
incidental to an army’s primary fighting function.”). To be
sure, punishing enemy belligerents who violate the
international rules governing armed conflicts is an “important
incident” to waging war. Quirin, 317 U.S. at 28. Such
punishment helps encourage adherence to the laws of war.
But restricting the military’s ability to intrude on the
judiciary’s domain hardly raises the types of concerns that
enforcing the limits on the President’s other war powers
could.

                               B.

      Judge Millett and Judge Wilkins take a very different
tack. Although seeming to recognize the lack of legal support
for prosecuting inchoate conspiracy before pure law-of-war
military commissions, they believe that we can nonetheless
affirm al Bahlul’s conviction because they think the facts, as
they understand them to have been found by the military
commission members, necessarily show that al Bahlul
engaged in conduct for which he could have been tried and
punished in a military commission. See Millett Op. at 2, 29–
38; Wilkins Op. at 1, 8–14. In other words, they would
overlook the fact that al Bahlul was charged only with
conspiracy as a standalone crime because, as they see it,
record evidence could have supported criminal liability under
international law—e.g., for the murder of protected persons
under a joint criminal enterprise theory of liability—and there
is, therefore, no Article I or Article III problem. Millett Op. at
29–38; Wilkins Op. at 13–14. That approach suffers from
several flaws.

     Most critically, the government never even hinted at such
an approach in its brief. To the contrary, at every turn, the
government defended al Bahlul’s conviction on the ground
that it could lawfully charge and prosecute him in a military
                              51
commission for the crime of inchoate conspiracy to violate
the laws of war. For instance, in response to al Bahlul’s
contention that military commissions have historically taken
cognizance of only completed war crimes, Pet’r’s Br. 13, the
government did not argue that the court could sustain his
conviction on the ground that al Bahlul was essentially found
guilty of participating in a completed war crime. It tacked in
the opposite direction, asserting that there is historical
precedent for trying conspiracy in cases where the object
offenses were never completed. See Resp’t’s Br. 42–43.
Moreover, in arguing that Congress acted consistently with
international law, the government did not take the opportunity
to defend al Bahlul’s conviction as resting on conduct
virtually the same as conduct for which he could have been
punished under international law. See id. Instead, it
acknowledged that the crime for which al Bahlul was charged
and convicted differed from any recognized international law
concept of criminal liability, because to support a war crime
conviction on a joint criminal enterprise theory of liability
international law generally “require[s] that the object offense
be completed or attempted,” id. at 56, and the government
stressed that the MCA’s “requirement that the defendant
personally commit an overt act is not the same as the
requirement that the object crime be completed,” id.

     It is by now well established that this court ordinarily
declines to decide cases based on arguments not raised by
either party. As we have explained on numerous occasions,
“[t]he premise of our adversarial system is that appellate
courts do not sit as self-directed boards of legal inquiry and
research.” Carducci v. Regan, 714 F.2d 171, 177 (D.C. Cir.
1983). Rather, we sit as “arbiters of legal questions presented
and argued by the parties before [us].” Id.; see United Parcel
Service, Inc. v. Mitchell, 451 U.S. 56, 60 n.2 (1981) (“We
decline to consider this argument since it was not raised by
                               52
either of the parties here or below.”); FED. R. APP. P.
28(a)(8)(A), (B) (requiring parties to set forth their legal and
factual contentions, “the reasons for them,” and “citations to
the authorities and parts of the record” on which they rely).
The reason for restraint is obvious: “Rulings on issues that
have not been fully argued run the risk of being improvident
or ill-advised.” United States v. West, 392 F.3d 450, 459
(D.C. Cir. 2004) (internal quotation marks omitted); cf.
Hamdan, 548 U.S. at 601 n.32 (plurality opinion) (criticizing
Justice Thomas’s focus on crimes not charged and noting that
“the Government plainly had available to it the tools and the
time it needed to charge petitioner with the various crimes
[Justice Thomas] refer[red] to, if it believed they were
supported by the allegations.”). Here, venturing down the path
proposed by Judge Millett and Judge Wilkins without the aid
of the parties runs the risk of misinterpreting record evidence
and failing to anticipate legal objections that the parties might
have to this approach.

     We put those concerns aside only to explain why we
believe that Judge Millett’s and Judge Wilkins’s analysis is
incorrect. First, we fail to see how their emphasis on facial
versus as-applied challenges makes a difference with respect
to al Bahlul’s Article III claim. The Article III inquiry focuses
on the nature of the offense charged. It is true that courts
generally should not concern themselves with the application
of statutes beyond the facts of the cases before them, but al
Bahlul never asks us to do so. The circumstances of his
prosecution make plain that his conviction runs afoul of
Article III because he was charged and prosecuted in a
military commission for a crime that is not triable before such
a tribunal. Thus, in seeking to overturn his conviction, al
Bahlul does not ask the court to consider the rights of
hypothetical defendants or to consider whether the MCA
might impermissibly authorize trial by military commission
                               53
for offenses other than what was charged here. He asks this
court to consider only the circumstances of his own
prosecution and conviction. And, for the reasons stated in Part
II, supra, his prosecution and resulting conviction in a
military commission for inchoate conspiracy was invalid.

     Attempting to avoid this conclusion, our colleagues
suggest an “as-applied” approach under which the court
would look past the charges against al Bahlul and uphold his
conviction so long as the military commission members’
findings could have supported criminal liability for a law-of-
war offense. See Millett Op. at 2, 29–38; Wilkins Op. at 1-5,
8–14. That, we think, not only asks the wrong question, but
would raise other serious problems with al Bahlul’s
conviction. Most critically, it would violate basic principles of
criminal justice, including that an accused know the charge
against him and that a conviction match the charge.
Importantly, al Bahlul was neither charged with nor convicted
of substantive war crimes, such as the murder of protected
persons, on a joint criminal enterprise or conspiracy theory of
liability. Instead, as seven members of this court recognize, al
Bahlul was charged with, tried for, and convicted of the
standalone crime of conspiracy. See Kavanaugh Op. at 1;
Henderson Op. at 1, incorporating by reference Al Bahlul II,
792 F.3d at 47 (Henderson, J., dissenting).

     In the United States, conspiracy is both a crime and a
theory of liability. Although the two concepts share the same
name, they are quite distinct. The crime of conspiracy makes
it unlawful for two or more persons to agree to commit a
crime. See, e.g., Iannelli, 420 U.S. at 777; Smith v. United
States, 133 S. Ct. 714, 719 (2013); Model Penal Code
§ 5.03(1). The crime of conspiracy is therefore complete as
soon as two or more conspirators enter into an agreement to
commit an unlawful act (and, depending on the jurisdiction,
                              54
as soon as one of the conspirators commits an overt act in
furtherance of the conspiracy’s objectives). It matters not at
all whether the conspiracy ever achieves its intended purpose.

     By contrast, conspiracy as a theory of liability is a
mechanism for holding individuals responsible for crimes
committed pursuant to a conspiratorial agreement. For
instance, if A and B agree to murder someone and A shoots
the gun while B acts as a lookout, B can be held just as
responsible for the murder as A. Under the Pinkerton
doctrine, an individual who joins a conspiracy can be held
responsible for completed crimes he or she agreed to as part
of the conspiracy and for any other crimes committed in
furtherance of the conspiracy that were its reasonably
foreseeable result. See Pinkerton v. United States, 328 U.S.
640, 646–47 (1946). Critically, when conspiracy serves as a
mode of liability, the defendant is charged with, tried for, and
convicted of substantive crimes, such as murder, bank
robbery, or wire fraud, that were committed in the course of a
conspiracy. That is, the indictment or charge sheet against the
defendant will list murder, bank robbery, or wire fraud as the
criminal offense for which the defendant is being tried, and
the final judgment of conviction will identify murder, bank
robbery, or wire fraud as the crime committed; conspiracy
simply acts as the theory on which the defendant is held
accountable for those crimes.

     As explained previously, international law has repeatedly
rejected conspiracy to commit war crimes as a standalone
offense. See Part II.B, supra. It does, however, embrace a
species of conspiracy liability known as joint criminal
enterprise. Hamdan, 548 U.S. at 611 n.40 (plurality opinion);
see Milutinović, Decision on Dragoljub Ojdanić’s Motion
Challenging Jurisdiction—Joint Criminal Enterprise, ¶ 26.
Under one formulation of joint criminal enterprise liability,
                               55
akin to Pinkerton liability, an individual can be held
responsible for the criminal acts of other members of an
enterprise so long as those acts were a “natural and
foreseeable consequence of the . . . [enterprise’s] common
purpose.” Prosecutor v. Tadíc, Case No. IT-94-1-A,
Judgement, ¶ 204 (Int’l Crim. Trib. for the Former
Yugoslavia, Appeals Chamber, July 15, 1999).

     As mentioned above, Judge Millett and Judge Wilkins
would ignore the government’s prosecutorial choice to charge
al Bahlul with, and convict him of, the crime of conspiracy,
see Charge Sheet, AE01, United States v. al Bahlul (M.C.
Feb. 26, 2008); see 10 U.S.C. § 950v(b)(28) (2006), and
would instead uphold his conviction on the ground that he
could have been punished in a military commission for other
international law-of-war offenses—like the murder of
protected persons on September 11, 2001—based on a joint
criminal enterprise or Pinkerton theory of liability, see Millett
Op. at 29–38; Wilkins Op. at 8–14. Meanwhile, our other
colleagues simply do not address the distinction between the
standalone crime of inchoate conspiracy of which al Bahlul
was convicted, and conspiracy as a theory of liability for
proven war crimes. See, e.g., Kavanaugh Op. at 15-19.

    The basic point here is an important one: the government
chose not to pursue charges against al Bahlul for the murder
of protected persons, attacking civilians, or any other
recognized war crime for which he could have been tried
under the 2006 MCA. See Charge Sheet, supra; see also Trial
Tr. 109–113; Oral Arg. Tr. 46–47 (Dec. 1, 2015)
(acknowledging that the government did not pursue a joint
criminal enterprise theory of liability for substantive war
crimes). Nor did the commission convict al Bahlul of
murdering protected persons, attacking civilians, or
committing any other substantive law-of-war offense. See
                               56
Findings Worksheet, AE074, United States v. al Bahlul (M.C.
Oct. 31, 2008). In fact, the military judge expressly instructed
commission members that in order to convict al Bahlul on
Charge I, the conspiracy charge, they did not need to find that
any of the alleged objects of the conspiracy—such as the
murder of protected persons—actually occurred. See Trial Tr.
848. They had to find only: (1) that al Bahlul entered into an
agreement with Osama bin Laden and others to commit an
offense triable by military commission; (2) that al Bahlul
knew the purpose of the agreement and joined it willingly and
with the intent to further that purpose; and (3) that al Bahlul
committed one of several overt acts in furtherance of the
agreement, none of which had to be criminal, much less an
international law-of-war offense. See id. 846, 849.

     If two of our colleagues believe that the military
commission members actually found al Bahlul guilty of
substantive offenses based on a conspiracy theory of liability
because they indicated on their Findings Worksheet that al
Bahlul was “guilty” of each object offense, including murder
of protected persons, see Millett Op. at 2, 31; see also
Findings Worksheet at 2, they are mistaken. Although that
section of the worksheet somewhat confusingly begins
“Guilty of Some, but Not All Objects of the Conspiracy” and
then gives the members a place to circle “guilty” or “not
guilty” next to each of the alleged objects of the conspiracy, it
is clear that by circling “guilty” next to each substantive
offense, the members were indicating only that al Bahlul had
joined a conspiracy that had as its object each of the listed
offenses. The charge was identified as “conspiracy,” Findings
Worksheet at 2, and the military commission judge expressly
instructed the members that “[i]n the specification of Charge
I, the accused is charged with the offense of conspiracy,” Trial
Tr. 845 (emphasis added). The judge never so much as hinted
that Charge I also encompassed substantive offenses on a
                              57
conspiracy theory of liability. See id. When one looks at the
Findings Worksheet as a whole, it is also clear that the
sections permitting the members to find al Bahlul “guilty” or
“not guilty” of specific objects of the conspiracy and specific
overt acts merely provided the members the opportunity to
find, with respect to the specification for Charge I, that the
conspiracy had some but not all of the alleged offenses as its
objects or that al Bahlul had committed some but not all of the
alleged overt acts. Tellingly, too, the government has never
argued that the Findings Worksheet shows that the
commission members actually found al Bahlul guilty of
substantive offenses.

     There is simply no basis for upholding a conviction for
the crime of inchoate conspiracy on the ground that a
defendant could have been charged with and convicted of
some other crime. To do so would violate the most
fundamental tenets of our criminal justice system—that a
defendant is entitled to notice of the charges against him and
that a conviction match the charge or be a lesser included
offense. As the Supreme Court has explained, due process
demands that a defendant have “notice of the specific charge,
and a chance to be heard in a trial of the issues raised by that
charge.” Cole v. Arkansas, 333 U.S. 196, 201 (1948). “It is as
much a violation of due process to send an accused to prison
following conviction of a charge on which he was never tried
as it would be to convict him upon a charge that was never
made.” Id. The Court has thus squarely rejected the notion
that an appellate court can sustain a conviction under a
provision never charged, explaining that “[t]o conform to due
process of law, [defendants] [a]re entitled to have the validity
of their convictions appraised on consideration of the case as
it was tried and as the issues were determined in the trial
court.” Id. at 202. We sincerely doubt that these most basic
principles of due process—well established under both
                              58
American and international law—can be cast aside in the
military commission context. See id.; see also, e.g., Geneva
Convention Relative to the Treatment of Prisoners of War,
supra, art. 105, 6 U.S.T. at 3396, 75 U.N.T.S. at 214
(“Particulars of the charge or charges on which the prisoner of
war is to be arraigned, as well as the documents which are
generally communicated to the accused by virtue of the laws
in force in the armed forces of the Detaining Power, shall be
communicated to the accused prisoner of war in a language
which he understands, and in good time before the opening of
the trial.”); ICTY Statute, supra, arts. 18, 20–21; ICTR
Statute, supra, arts. 17, 19–20; cf. Rome Statute, art. 22, § 2,
supra; United States v. Longmire, 39 M.J. 536, 538
(A.C.M.R. 1994) (recognizing in the court-martial context
that a “basic principle of due process” is that “an individual
should not be made to face criminal charges without having
been notified of what he must defend against and without
having been protected against double jeopardy”).

     But we have no need to rely on constitutional or
international-law principles to question the validity of an
affirmance on grounds other than those charged and tried, as
both the Military Commissions Act of 2006 and the rules
promulgated thereunder incorporate these same notice
principles. The Act “establish[es] a two-step process for
initiating a trial before a military commission,” Obaydullah v.
Obama, 609 F.3d 444, 445–46 (D.C. Cir. 2010), pursuant to
which an authorized person subject to the Uniform Code of
Military Justice must swear a charge, under oath, against a
defendant, 10 U.S.C. § 948q(a); see Manual for Military
Commissions, Rule for Military Commissions (R.M.C.) 307,
at II-15 (2007). The Act further requires that, once charges are
sworn against an accused, he be promptly informed of them.
10 U.S.C. § 948q(b); see R.M.C. 308. The Act also specifies,
in language similar to that used in the Geneva Conventions,
                               59
see Geneva Convention Relative to the Treatment of Prisoners
of War, supra, art. 105, 6 U.S.T. at 3396, 75 U.N.T.S. at 214,
that the government must serve the accused with “a copy of
the charges upon which trial is to be had in English and, if
appropriate, in another language that the accused understands,
sufficiently in advance of trial to prepare a defense,” 10
U.S.C. § 948s. With minor exceptions not relevant here, any
fact that increases the maximum punishment authorized must
be alleged in the charge’s specification, R.M.C. 307(c)(3),
and substantive changes to the charges cannot be made
without newly referring charges and notifying the accused,
R.M.C. 603(d). Finally, Rule 801(d) on “[u]ncharged
offenses” provides that, “[i]f during the trial there is evidence
that the accused may be guilty of an untried offense not
alleged in any specification before the commission, the
commission shall proceed with the trial of the offense
charged.” R.M.C. 801(d) (emphasis added). Upholding al
Bahlul’s conviction on the ground that he could have been
tried for and convicted of some other offense would, at the
least, raise serious questions as to whether this court has
departed from Congress’s express instructions regarding the
rights and procedural protections to which alien enemy
belligerents are entitled.

     Even if that were not enough, our colleagues’ approach
would usurp the fact-finding role of the military commission
members, see 10 U.S.C. § 949l; R.M.C. 502(a)(2) (“The
members of a military commission shall determine whether
the accused is proved guilty . . . .”); R.M.C. 921 (addressing
the members’ responsibility to determine guilt with respect to
each charge and specification), and transgress the statutory
limits on this court’s appellate review. Perhaps most
importantly, this court’s authority under the MCA is limited
to “approv[ing]” a finding of guilty or “affirm[ing] . . . so
much of the finding as includes a lesser included offense.” 10
                              60
U.S.C. § 950a; see id. § 950g. The offenses our colleagues
glimpse in the record are neither the charged inchoate
conspiracy nor lesser-included offenses of that crime. See
Kelly v. United States, 370 F.2d 227, 228 (D.C. Cir. 1966);
FED. R. CRIM. P. 31(c).

     Finally, our colleagues seem to rely on a narrow reading
of the 2006 MCA’s conspiracy provision as evidence that the
government really obtained a conviction for al Bahlul’s
participation in a conspiracy that resulted in completed war
crimes, an offense that they believe would be triable in a
military commission because it would be akin to holding an
individual responsible under international law for completed
war crimes on a joint criminal enterprise theory of liability.
They believe that the statute’s reference to “victims,” see 10
U.S.C. § 950v(b)(28) (2006), requires that there be a
completed law-of-war offense to convict an individual of
“conspiracy” within the meaning of that provision, see Millett
Op. at 30; Wilkins Op. at 9. We think it quite unwise to opine
on the meaning of the statute’s opaque reference to “victims”
without the aid of briefing, especially given that, during its
more than four years of litigating this case, the government
has never pressed such an interpretation of the statute and has
instead repeatedly insisted that the statute criminalizes
inchoate conspiracy. Even if our colleagues are correct, that
would have no effect on the proper outcome in this case. It
would only raise additional questions as to whether al
Bahlul’s trial for the crime of inchoate conspiracy was
statutorily authorized. The Article III problem lying at the
heart of this case thus cannot be solved by reimagining the
statute under which al Bahlul was convicted or the crimes for
which he was charged, as doing so only raises other
fundamental legal problems.
                              61
    To be sure, Judge Millett and Judge Wilkins’s approach
would allow us to sustain the conviction of a man who—by
his own admission—proudly assisted the terrorist group
responsible for one of the most terrible attacks ever
perpetrated against the United States. But that approach is
unavailable to us. The government chose to prosecute al
Bahlul in a military commission for the crime of inchoate
conspiracy. It also never suggested that this court can uphold
al Bahlul’s conviction on the ground that he could have been
convicted of other charges—and for good reason. That
approach raises serious due process concerns and conflicts
with the military-commission procedures Congress requires.

                              IV.

     One may wonder, “why the fuss?” Stern v. Marshall, 564
U.S. 462, 502 (2011). After all, the government is not seeking
to prosecute cyber or drug crimes before military
commissions; it is seeking only to prosecute conspiracies to
commit recognized war crimes. Can such a modest expansion
of military-commission jurisdiction really threaten the
Constitution’s separation of powers? As in Stern v. Marshall,
“[t]he short but emphatic answer is yes.” Id. “[O]ur
Constitution . . . commands that the independence of the
Judiciary be jealously guarded . . . .” Northern Pipeline, 458
U.S. at 60 (plurality opinion). The political branches “may no
more lawfully chip away at the authority of the Judicial
Branch than [they] may eliminate it entirely.” Stern, 564 U.S.
at 503. And “[a]lthough it may be that it is the obnoxious
thing in its mildest and least repulsive form, we cannot
overlook the intrusion: illegitimate and unconstitutional
practices get their first footing in that way, namely, by silent
approaches and slight deviations from legal modes of
procedure.” Id. (internal quotation marks omitted).
                              62
     Here, it is easy to see how allowing the political branches
to stretch Article III’s exception for law-of-war military
commissions to encompass inchoate conspiracy charges
could represent just the first step toward a much greater
usurpation of the judiciary’s domain. Against the backdrop of
the war on terror, in which many of the traditional constraints
on the use of law-of-war military commissions are
disappearing, the government articulates a breathtakingly
expansive view of the political branches’ authority to subject
non-servicemembers to military trial and punishment. Indeed,
it admits only two constitutional constraints on its power to
try individuals in law-of-war military commissions: the
charges must allege (1) that the individuals are “enemy
belligerents” who (2) engaged in proscribed conduct “in the
context of and associated with hostilities.” Oral Arg. Tr. 37–
38 (Dec. 1, 2015).

     Critically, the government’s suggestion that the
defendant’s status as an enemy belligerent in the context of
hostilities suffices to subject him to trial by military
commission ignores the Supreme Court’s focus on the
offenses triable to law-of-war military commissions, in
addition to the status of the offenders. Thus the Court has
focused on “the question whether it is within the
constitutional power of the national government to place
petitioners upon trial before a military commission for the
offenses with which they are charged.” Quirin, 317 U.S. at 29
(emphasis added). In Quirin, the Court “assume[d] that there
are acts” that could not be tried by military commission
“because they are of that class of offenses constitutionally
triable only by a jury.” Id. (emphases added). So, too, in
Yamashita. 327 U.S. at 8. And in Hamdan, the Court
explained that the status of the offender (being a member of a
foreign armed force) and the nature of the offense were both
necessary conditions for the exercise of jurisdiction by a law-
                              63
of-war military commission. See Hamdan, 548 U.S. at 597–
98 (plurality opinion) (citing WINTHROP, MILITARY LAW,
supra, at 836–39); accord id. at 683 (Thomas, J., dissenting).

     But putting that aside, the extent to which the
government’s proposed limits have any force is far from
clear. What does it mean, for instance, for an individual to
have committed an offense in the context of hostilities? The
answer is uncertain, both as a temporal and geographic
matter. We would be willing to wager that if you asked
Americans when the United States’ “war” with al Qaeda
began, most would say September 11, 2001. Even executive
branch officials often cite that date as the beginning of
hostilities against al Qaeda and its affiliates. For example, for
certain naturalization purposes, the President “designate[d] as
a period in which the Armed Forces of the United States were
engaged in armed conflict with a hostile foreign force the
period beginning on September 11, 2001.” E.O. 13,269, 67
Fed. Reg. 45,287 (July 3, 2002); see Memorandum for the
Attorney General, from Jay S. Bybee, Assistant Attorney
General, Office of Legal Counsel, Re: Determination of
Enemy Belligerency and Military Detention (June 8, 2002),
available at 2002 WL 34482990, at *7 (“[T]he September 11,
2001 attacks on the World Trade Center and the Pentagon
began an international armed conflict between the United
States and the al Qaeda terrorist organization.”). But in a
pending military-commission case, the government seeks to
hold an alleged member of al Qaeda responsible for a failed
attack on a U.S. vessel that occurred in January 2000. It takes
the position in that case that the United States’ war with al
Qaeda goes back “to at least 1998,” and it appears to believe
that the conflict may date as far back as 1992. See Brief for
the United States 5, 41, United States v. Al-Nashiri, Nos. 15-
5020 & 15-1023 (D.C. Cir. Dec. 28, 2015). But see United
States v. Al-Nashiri, --- F.3d --- (D.C. Cir. 2016) (recognizing
                              64
as unsettled for purposes of mandamus when hostilities began
against Al Qaeda).

     If the government’s view in this case that military
commission jurisdiction is limited only by Congress’ war
powers were to prevail, Congress and the President could
authorize military prosecutions in many situations that we
traditionally think of as within the exclusive province of
domestic law enforcement agencies and civilian courts.
Suppose, for instance, that the FBI launches an investigation
into three lawful permanent residents who have lived in the
United States since early childhood. Searching an apartment
in Virginia that the three share, it discovers pipe bombs, al
Qaeda propaganda, and a map of the Washington, D.C. metro
system. The government arrests the three and wishes to
prosecute them for conspiracy to kill innocent civilians.
Under the government’s view of things, the Constitution
would pose no bar to transferring the individuals into military
custody and prosecuting them before a military commission.
In fact, when presented with this hypothetical at oral
argument, government counsel conceded that these facts
“might well be enough” to try the individuals in a military
tribunal. Oral Arg. Tr. 51–53 (Dec. 1, 2015); see also
Kavanaugh Op. at 30–31. This is a dangerous suggestion to
say the least. Cf. Reid, 354 U.S. at 23–24 (plurality opinion)
(“The Founders envisioned the army as a necessary
institution, but one dangerous to liberty if not confined within
its essential bounds.”).

    But the government’s position gets more dangerous still.
Now suppose that the three are U.S. citizens. Could the
government do an end run around Article III solely because
they had some connection to the “war” on terrorism? It would
seem so. See Quirin, 317 U.S. at 37–38 (holding that a
saboteur’s U.S. citizenship was irrelevant to a commission’s
                              65
authority to try him for law-of-war offenses). What if the FBI
instead discovered that the three U.S. citizens sent $200 to the
humanitarian wing of an organization that the United States
designated a foreign terrorist organization, earmarked for
training in human-rights advocacy that the donors hope will
turn the organization away from terrorist activities? Could the
three be shipped off to a military base and tried for material
support for terrorism—an offense unrecognized under
international law but made punishable under the Military
Commissions Act? 10 U.S.C. § 950t(25); cf. Holder v.
Humanitarian Law Project, 561 U.S. 1, 7–11 (2010). The
government seems to think so.

     According to Judge Kavanaugh’s opinion, the court need
not concern itself with the limits (or lack thereof) on the
political branches’ authority to make conduct punishable by
military commission because whatever those limits might be,
the punishment of conspiracies to commit war crimes
certainly falls within them. See Kavanaugh Op. at 25. But if
international law does not mark the boundaries between
civilian and military jurisdiction, what does? On this, our
colleagues are silent. Based on the principles articulated by
the government and embraced in Judge Kavanaugh’s opinion,
however, it would seem that Congress and the President could
vest military commissions with authority to try enemy
belligerents for almost any crime so long as it related in some
way to “hostilities.” Id. at 24–25. Especially in this new era
of “war” against difficult-to-identify enemies on difficult-to-
identify “battlefields,” such positions would appear to leave
few, if any, enforceable limits on the political branches’
authority to avoid Article III courts and prosecute individuals
in military commissions. Thus, although allowing military
commissions to take cognizance of inchoate conspiracy
charges might seem to some a small and harmless
encroachment on the judiciary’s domain, it could very well
                               66
open the door to much broader intrusions. Any such intrusion
would be all the more pernicious here and corrosive of Article
III given that, in this case, the government has made no effort
to demonstrate the “military necessity” that has traditionally
been a prerequisite to resort to military commissions.
Hamdan, 548 U.S. at 590; see also id. at 598–99 (plurality
opinion); id. at 646 (Kennedy, J., concurring). To accept the
government’s position would embed the use of military
commissions “more deeply in our law and thinking,” ready to
be “expand[ed] . . . to new purposes.” Korematsu v. United
States, 323 U.S. 214, 246 (1944) (Jackson, J. dissenting). A
majority of this court declines today to deal any such “blow to
liberty.” Id.

                           *    *    *

      Before concluding, we think it worth underscoring the
result of today’s decision. Eight of the nine judges deciding
this appeal believe that the question lying at the heart of it,
i.e., whether Congress can lawfully vest military commissions
with jurisdiction over the crime of inchoate conspiracy, is
deserving of de novo review. Only four of those considering
the question de novo answer it in the affirmative.
Accordingly, the majority of judges declines to endorse the
government’s view of the Constitution. Today’s decision thus
provides no precedential value for the government’s efforts to
divert the trial of conspiracy or any other purely domestic
crime to law-of-war military commissions.

     We, for the reasons discussed, see no lawful basis for the
government’s claimed power. Whatever deference the
judiciary may owe to the political branches in matters of
national security and defense, it is not absolute. Far from it, it
is the duty of the courts “in time of war as well as in time of
peace, to preserve unimpaired the constitutional safeguards of
                             67
civil liberty.” Quirin, 317 U.S. at 19. And although the
government might well be entitled to detain al Bahlul as an
enemy belligerent, see Hamdi, 542 U.S. at 518–24 (plurality
opinion), it does not have the “power to switch the
Constitution on and off at will,” Boumediene, 553 U.S. at 766.
Its prosecution of al Bahlul in a military commission for
conspiracy to violate the laws of war exceeded the scope of
Article III’s exception for law-of-war military commissions
and, as a result, violated Article III. Accordingly, we would
vacate his conspiracy conviction.
