(Slip Opinion)              OCTOBER TERM, 2014                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                  MCFADDEN v. UNITED STATES

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                 THE FOURTH CIRCUIT

       No. 14–378.      Argued April 21, 2015—Decided June 18, 2015
Petitioner McFadden was arrested and charged with distributing con-
  trolled substance analogues in violation of the federal Controlled
  Substance Analogue Enforcement Act of 1986 (Analogue Act), which
  identifies a category of substances substantially similar to those
  listed on the federal controlled substances schedules, 21 U. S. C.
  §802(32)(A), and instructs courts to treat those analogues as schedule
  I controlled substances if they are intended for human consumption,
  §813. Arguing that he did not know the “bath salts” he was distrib-
  uting were regulated as controlled substance analogues, McFadden
  sought an instruction that would have prevented the jury from find-
  ing him guilty unless it found that he knew the substances he dis-
  tributed had chemical structures and effects on the central nervous
  system substantially similar to those of controlled substances. In-
  stead, the District Court instructed the jury that it need only find
  that McFadden knowingly and intentionally distributed a substance
  with substantially similar effects on the central nervous system as a
  controlled substance and that he intended that substance to be con-
  sumed by humans. McFadden was convicted. The Fourth Circuit af-
  firmed, holding that the Analogue Act’s intent element required only
  proof that McFadden intended the substance to be consumed by hu-
  mans.
Held: When a controlled substance is an analogue, §841(a)(1) requires
 the Government to establish that the defendant knew he was dealing
 with a substance regulated under the Controlled Substances Act or
 Analogue Act. Pp. 4–11.
    (a) In addressing the treatment of controlled substance analogues
 under federal law, one must look to the CSA, which, as relevant here,
 makes it “unlawful for any person knowingly . . . to distribute . . . a
2                   MCFADDEN v. UNITED STATES

                                  Syllabus

    controlled substance.” §841(a)(1). The ordinary meaning of that pro-
    vision requires a defendant to know only that the substance he is dis-
    tributing is some unspecified substance listed on the federal drug
    schedules. Thus, the Government must show either that the defend-
    ant knew he was distributing a substance listed on the schedules,
    even if he did not know which substance it was, or that the defendant
    knew the identity of the substance he was distributing, even if he did
    not know it was listed on the schedules.
       Because the Analogue Act extends that framework to analogous
    substances, the CSA’s mental-state requirement applies when the
    controlled substance is, in fact, an analogue. It follows that the Gov-
    ernment must prove that a defendant knew that the substance he
    was distributing was “a controlled substance,” even in prosecutions
    dealing with analogues. That knowledge requirement can be estab-
    lished in two ways: by evidence that a defendant knew that the sub-
    stance he was distributing is controlled under the CSA or Analogue
    Act, regardless of whether he knew the substance’s identity; or by ev-
    idence that the defendant knew the specific analogue he was distrib-
    uting, even if he did not know its legal status as a controlled sub-
    stance analogue. A defendant with knowledge of the features
    defining a substance as a controlled substance analogue, §802(32)(A),
    knows all of the facts that make his conduct illegal. Pp. 4–8.
       (b) The Fourth Circuit did not adhere to §813’s command to treat a
    controlled substance analogue as a controlled substance listed in
    schedule I by applying §841(a)(1)’s mental-state requirement. In-
    stead, it concluded that the only mental-state requirement for ana-
    logue prosecutions is the one in §813—that an analogue be “intended
    for human consumption.” That conclusion is inconsistent with the
    text and structure of the statutes.
       Neither the Government’s nor McFadden’s interpretation fares any
    better. The Government’s contention that §841(a)(1)’s knowledge re-
    quirement as applied to analogues is satisfied if the defendant knew
    he was dealing with a substance regulated under some law ignores
    §841(a)(1)’s requirement that a defendant know he was dealing with
    “a controlled substance.” That term includes only drugs listed on the
    federal drug schedules or treated as such by operation of the Ana-
    logue Act; it is not broad enough to include all substances regulated
    by any law. McFadden contends that a defendant must also know
    the substance’s features that cause it to fall within the scope of the
    Analogue Act. But the key fact that brings a substance within the
    scope of the Analogue Act is that the substance is “controlled,” and
    that fact can be established in the two ways previously identified.
    Staples v. United States, 511 U. S. 600, distinguished. Contrary to
    McFadden’s submission, the canon of constitutional avoidance “has
                     Cite as: 576 U. S. ____ (2015)                    3

                                Syllabus

  no application” in the interpretation of an unambiguous statute such
  as this one. Warger v. Shauers, 574 U. S. ___, ___. But even if the
  statute were ambiguous, the scienter requirement adopted here “al-
  leviate[s] vagueness concerns” under this Court’s precedents. Gonza-
  les v. Carhart, 550 U. S. 124, 149. Pp. 8–10.
     (c) The Government argues that no rational jury could have con-
  cluded that McFadden was unaware that the substances he was dis-
  tributing were controlled under the CSA or Analogue Act and that
  any error in the jury instruction was therefore harmless. The Fourth
  Circuit, which did not conduct a harmless-error analysis, is to consid-
  er that issue in the first instance. Pp. 10–11.
753 F. 3d 432, vacated and remanded.

   THOMAS, J., delivered the opinion of the Court, in which SCALIA,
KENNEDY, GINSBURG, BREYER, ALITO, SOTOMAYOR, and KAGAN, JJ.,
joined. ROBERTS, C. J., filed an opinion concurring in part and concur-
ring in the judgment.
                       Cite as: 576 U. S. ____ (2015)                              1

                            Opinion of the Court

    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash-
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                                  No. 14–378
                                  _________________


 STEPHEN DOMINICK MCFADDEN, PETITIONER v.

             UNITED STATES

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

           APPEALS FOR THE FOURTH CIRCUIT

                                [June 18, 2015] 


  JUSTICE THOMAS delivered the opinion of the Court.
  The Controlled Substance Analogue Enforcement Act of
1986 (Analogue Act) identifies a category of substances
substantially similar to those listed on the federal con-
trolled substance schedules, 21 U. S. C. §802(32)(A), and
then instructs courts to treat those analogues, if intended
for human consumption, as controlled substances listed on
schedule I for purposes of federal law, §813. The Con-
trolled Substances Act (CSA) in turn makes it unlawful
knowingly to manufacture, distribute, or possess with
intent to distribute controlled substances. §841(a)(1). The
question presented in this case concerns the knowledge
necessary for conviction under §841(a)(1) when the con-
trolled substance at issue is in fact an analogue.
  We hold that §841(a)(1) requires the Government to
establish that the defendant knew he was dealing with “a
controlled substance.” When the substance is an ana-
logue, that knowledge requirement is met if the defendant
knew that the substance was controlled under the CSA or
the Analogue Act, even if he did not know its identity. The
knowledge requirement is also met if the defendant knew
2              MCFADDEN v. UNITED STATES

                     Opinion of the Court

the specific features of the substance that make it a “ ‘con-
trolled substance analogue.’ ” §802(32)(A). Because the
U. S. Court of Appeals for the Fourth Circuit approved a
jury instruction that did not accurately convey this
knowledge requirement, we vacate its judgment and re-
mand for that court to determine whether the error was
harmless.
                              I
  In 2011, law enforcement officials in Charlottesville,
Virginia, began investigating individuals at a Char-
lottesville video store for suspected distribution of “bath
salts”—various recreational drugs used to produce effects
similar to those of cocaine, methamphetamine, and other
controlled substances. The owner of the store, Lois
McDaniel, had been purchasing bath salts from petitioner
Stephen McFadden for several months. McFadden had
marketed the substances to her as “Alpha,” “No Speed,”
“Speed,” “Up,” and “The New Up,” and had compared them
to cocaine and crystal meth. He had often sold those
products with labels borrowing language from the Ana-
logue Act, asserting that the contents were “not for human
consumption” or stating that a particular product “does
not contain any of the following compounds or analogues
of the following compounds” and listing controlled sub-
stances. McDaniel purchased the bath salts for $15 per
gram and resold them for $30 to $70 per gram.
  After investigators had conducted two controlled buys
from the store and confronted McDaniel, she agreed to
cooperate in their investigation by making five controlled
buys from McFadden. The Government intercepted the
substances McFadden sent when they arrived at the local
FedEx store. Like the substances sold in the video store,
these substances were white and off-white powders pack-
aged in small plastic bags. Chemical analysis identified
the powders as containing, among other substances, 3,4-
                 Cite as: 576 U. S. ____ (2015)           3

                     Opinion of the Court

Methylenedioxypyrovalerone, also known as MDPV; 3,4-
Methylenedioxy-N-methylcathinone, also known as Meth-
ylone or MDMC; and 4-Methyl-N-ethylcathinone, also
known as 4-MEC. When ingested, each of these sub-
stances is capable of producing effects on the central
nervous system similar to those that controlled substances
(such as cocaine, methamphetamine, and methcathinone)
produce.
   A federal grand jury indicted McFadden on eight counts
of distribution of controlled substance analogues and one
count of conspiracy. At trial, McFadden argued that he
did not know the substances he was distributing were
regulated as controlled substances under the Analogue
Act. He and the Government also disagreed about what
knowledge was required for a conviction. The Government
sought an instruction requiring only “[t]hat the defendant
knowingly and intentionally distributed a mixture or
substance . . . [t]hat . . . was a controlled substance ana-
logue . . . with the intent that it be consumed by humans.”
App. 26–27. McFadden sought a more demanding instruc-
tion requiring that he “knew that the substances that he
was distributing possessed the characteristics of controlled
substance analogues,” including their chemical structures
and effects on the central nervous system. Id., at 29–30.
The District Court compromised, instructing the jury that
the statute required that “the defendant knowingly and
intentionally distributed a mixture or substance that has”
substantially similar effects on the nervous system as a
controlled substance and “[t]hat the defendant intended
for the mixture or substance to be consumed by humans.”
Id., at 40.
   The jury convicted McFadden on all nine counts. On
appeal, McFadden insisted that the District Court “erred
in refusing to instruct the jury that the government was
required to prove that he knew, had a strong suspicion, or
deliberately avoided knowledge that the [substances]
4              MCFADDEN v. UNITED STATES

                     Opinion of the Court

possessed the characteristics of controlled substance ana-
logues.” 753 F. 3d 432, 443 (CA4 2014). Rejecting that
argument, the Court of Appeals affirmed. Id., at 444, 446.
Stating that it was bound by Circuit precedent, the court
concluded that the “intent element [in the Act] requires
[only] that the government prove that the defendant
meant for the substance at issue to be consumed by hu-
mans.” Id., at 441; see id., at 444.
  We granted a writ of certiorari, 574 U. S ___ (2015), and
now vacate the judgment of the Court of Appeals and
remand.
                              II

                               A

   The Analogue Act requires a controlled substance ana-
logue, if intended for human consumption, to be treated
“as a controlled substance in schedule I” for purposes of
federal law. §1201, 100 Stat. 3207–13, 21 U. S. C. §813.
We therefore must turn first to the statute that addresses
controlled substances, the CSA. The CSA makes it “un-
lawful for any person knowingly or intentionally . . . to
manufacture, distribute, or dispense, or possess with
intent to manufacture, distribute, or dispense, a controlled
substance.”     §401(a)(1), 84 Stat. 1260, 21 U. S. C.
§841(a)(1). Under the most natural reading of this provi-
sion, the word “knowingly” applies not just to the statute’s
verbs but also to the object of those verbs—“a controlled
substance.” See Flores-Figueroa v. United States, 556
U. S. 646, 650 (2009); id., at 657 (SCALIA, J., concurring in
part and concurring in judgment); id., at 660–661 (ALITO,
J., concurring in part and concurring in judgment). When
used as an indefinite article, “a” means “[s]ome undeter-
mined or unspecified particular.” Webster’s New Interna-
tional Dictionary 1 (2d ed. 1954). And the CSA defines
“controlled substance” as “a drug or other substance, or
immediate precursor, included in schedule I, II, III, IV, or
                    Cite as: 576 U. S. ____ (2015)                   5

                         Opinion of the Court

V.” §802(6) (internal quotation marks omitted). The
ordinary meaning of §841(a)(1) thus requires a defendant
to know only that the substance he is dealing with is some
unspecified substance listed on the federal drug schedules.
The Courts of Appeals have recognized as much. See, e.g.,
United States v. Andino, 627 F. 3d 41, 45–46 (CA2 2010);
United States v. Gamez-Gonzalez, 319 F. 3d 695, 699 (CA5
2003); United States v. Martinez, 301 F. 3d 860, 865 (CA7
2002).
   That knowledge requirement may be met by showing
that the defendant knew he possessed a substance listed
on the schedules, even if he did not know which substance
it was. Take, for example, a defendant whose role in a
larger drug organization is to distribute a white powder to
customers. The defendant may know that the white pow-
der is listed on the schedules even if he does not know
precisely what substance it is. And if so, he would be
guilty of knowingly distributing “a controlled substance.”
   The knowledge requirement may also be met by showing
that the defendant knew the identity of the substance he
possessed. Take, for example, a defendant who knows he
is distributing heroin but does not know that heroin is
listed on the schedules, 21 CFR §1308.11 (2014). Because
ignorance of the law is typically no defense to criminal
prosecution, Bryan v. United States, 524 U. S. 184, 196
(1998), this defendant would also be guilty of knowingly
distributing “a controlled substance.”1
——————
  1 The Courts of Appeals have held that, as with most mens rea re-

quirements, the Government can prove the requisite mental state
through either direct evidence or circumstantial evidence. Direct
evidence could include, for example, past arrests that put a defendant
on notice of the controlled status of a substance. United States v.
Abdulle, 564 F. 3d 119, 127 (CA2 2009). Circumstantial evidence could
include, for example, a defendant’s concealment of his activities, eva-
sive behavior with respect to law enforcement, knowledge that a
particular substance produces a “high” similar to that produced by
controlled substances, and knowledge that a particular substance is
6                 MCFADDEN v. UNITED STATES

                         Opinion of the Court

  The Analogue Act extends the framework of the CSA to
analogous substances. 21 U. S. C. §813. The Act defines a
“controlled substance analogue” as a substance:
       “(i) the chemical structure of which is substantially
     similar to the chemical structure of a controlled sub-
     stance in schedule I or II;
       “(ii) which has a stimulant, depressant, or halluci-
     nogenic effect on the central nervous system that is
     substantially similar to or greater than the stimulant,
     depressant, or hallucinogenic effect on the central
     nervous system of a controlled substance in schedule I
     or II; or
       “(iii) with respect to a particular person, which such
     person represents or intends to have a stimulant, de-
     pressant, or hallucinogenic effect on the central nerv-
     ous system that is substantially similar to or greater
     than the stimulant, depressant, or hallucinogenic ef-
     fect on the central nervous system of a controlled sub-
     stance in schedule I or II.” §802(32)(A).
It further provides, “A controlled substance analogue
shall, to the extent intended for human consumption, be
treated, for the purposes of any Federal law as a controlled
substance in schedule I.” §813.
  The question in this case is how the mental state re-
quirement under the CSA for knowingly manufacturing,
distributing, or possessing with intent to distribute “a
controlled substance” applies when the controlled sub-
stance is in fact an analogue. The answer begins with
§841(a)(1), which expressly requires the Government to
prove that a defendant knew he was dealing with “a con-
trolled substance.” The Analogue Act does not alter that
provision, but rather instructs courts to treat controlled
——————
subject to seizure at customs. United States v. Ali, 735 F. 3d 176, 188–
189 (CA4 2013). The Government presented such circumstantial
evidence in this case, and neither party disputes that this was proper.
                      Cite as: 576 U. S. ____ (2015)                        7

                           Opinion of the Court

substance analogues “as . . . controlled substance[s] in
schedule I.” §813. Applying this statutory command, it
follows that the Government must prove that a defendant
knew that the substance with which he was dealing was “a
controlled substance,” even in prosecutions involving an
analogue.2
   That knowledge requirement can be established in two
ways. First, it can be established by evidence that a de-
fendant knew that the substance with which he was deal-
ing is some controlled substance—that is, one actually
listed on the federal drug schedules or treated as such by
operation of the Analogue Act—regardless of whether he
knew the particular identity of the substance. Second, it
can be established by evidence that the defendant knew
the specific analogue he was dealing with, even if he did
not know its legal status as an analogue. The Analogue
Act defines a controlled substance analogue by its fea-
tures, as a substance “the chemical structure of which is
substantially similar to the chemical structure of a con-
trolled substance in schedule I or II”; “which has a stimu-
lant, depressant, or hallucinogenic effect on the central
nervous system that is substantially similar to or greater
than” the effect of a controlled substance in schedule I or
II; or which is represented or intended to have that effect
with respect to a particular person. §802(32)(A). A de-
fendant who possesses a substance with knowledge of
——————
  2 The Government has accepted for the purpose of this case that it
must prove two elements to show that a substance is a controlled
substance analogue under the definition in §802(32)(A): First, that an
alleged analogue is substantially similar in chemical structure to a
controlled substance, §802(32)(A)(i). Second, that an alleged analogue
either has, or is represented or intended to have, a stimulant, depres-
sant, hallucinogenic effect on the central nervous system that is sub-
stantially similar to that of a controlled substance, §§802(32)(A)(ii), (iii).
Brief for United States 3. Because we need not decide in this case
whether that interpretation is correct, we assume for the sake of
argument that it is.
8                MCFADDEN v. UNITED STATES

                        Opinion of the Court

those features knows all of the facts that make his conduct
illegal, just as a defendant who knows he possesses heroin
knows all of the facts that make his conduct illegal. A
defendant need not know of the existence of the Analogue
Act to know that he was dealing with “a controlled
substance.”
                              B
   The Court of Appeals did not adhere to §813’s command
to treat a controlled substance analogue “as a controlled
substance in schedule I,” and, accordingly, it did not apply
the mental-state requirement in §841(a)(1). Instead, it
concluded that the only mental state requirement for
prosecutions involving controlled substance analogues is
the one in §813—that the analogues be “intended for
human consumption.” 753 F. 3d, at 436 (citing United
States v. Klecker, 348 F. 3d 69, 71 (CA4 2003)). Because
that interpretation is inconsistent with the text and struc-
ture of the statutes, we decline to adopt it.
   Unsurprisingly, neither the Government nor McFadden
defends the Court of Appeals’ position. But their alterna-
tive interpretations fare no better. The Government
agrees that the knowledge requirement in §841(a)(1)
applies to prosecutions involving controlled substance
analogues, yet contends that it is met if the “defendant
knew he was dealing with an illegal or regulated sub-
stance” under some law. Brief for United States 15.
Section 841(a)(1), however, requires that a defendant
knew he was dealing with “a controlled substance.” That
term includes only those drugs listed on the federal drug
schedules or treated as such by operation of the Analogue
Act. §§802(6), 813. It is not broad enough to include all
substances regulated by any law.3
——————
  3 Although the Government must prove that a defendant knew that

the substance in question was “a controlled substance” under federal
law, the Government need not introduce direct evidence of such
                    Cite as: 576 U. S. ____ (2015)                  9

                        Opinion of the Court

   For his part, McFadden contends that, in the context of
analogues, knowledge of “a controlled substance” can only
be established by knowledge of the characteristics that
make a substance an “analogue” under the Act. In sup-
port of that argument, he relies heavily on our conclusion
in Staples v. United States, 511 U. S. 600 (1994), that a
statute making it “ ‘unlawful for any person . . . to receive
or possess a firearm which is not registered to him in the
National Firearms Registration and Transfer Record,’ ” id.,
at 605 (quoting 26 U. S. C. §5861(d)), required proof that a
defendant “knew of the features of his AR–15 that brought
it within the scope of the Act,” 511 U. S., at 619. McFad-
den reasons by analogy that a defendant convicted under
§841(a)(1) must also know the features of the substance
that brought it within the scope of the Analogue Act. But
that position ignores an important textual distinction
between §841(a)(1) and the statute at issue in Staples.
The statute at issue in Staples defined “a firearm” by its
physical features such as the length of its barrel and its
capacity to shoot more than one shot with a single function
of the trigger. Unlike those physical features that brought
the firearm “within the scope of ” that statute, the fea-
ture of a substance “that br[ings] it within the scope of”
§841(a)(1) is the fact that it is “ ‘controlled.’ ” §802(6).
Knowledge of that fact can be established in the two
ways previously discussed: either by knowledge that a
substance is listed or treated as listed by operation of
the Analogue Act, §§802(6), 813, or by knowledge of the
physical characteristics that give rise to that treatment.
——————
knowledge. As with prosecutions involving substances actually listed
on the drug schedules, the Government may offer circumstantial
evidence of that knowledge. See n. 1, supra. In such cases, it will be
left to the trier of fact to determine whether the circumstantial evi-
dence proves that the defendant knew that the substance was a con-
trolled substance under the CSA or Analogue Act, as opposed to under
any other federal or state laws.
10              MCFADDEN v. UNITED STATES

                      Opinion of the Court

Supra, at 7.
   McFadden also invokes the canon of constitutional
avoidance, arguing that we must adopt his interpretation
of the statute lest it be rendered unconstitutionally vague.
But that argument fails on two grounds. Under our prec-
edents, this canon “is a tool for choosing between compet-
ing plausible interpretations of a provision.” Warger v.
Shauers, 574 U. S. ___, ___ (2014) (slip op., at 10) (internal
quotation marks omitted). It “has no application” in the
interpretation of an unambiguous statute such as this one.
See ibid. (internal quotation marks omitted). Even if this
statute were ambiguous, McFadden’s argument would
falter. Under our precedents, a scienter requirement in a
statute “alleviate[s] vagueness concerns,” “narrow[s] the
scope of the [its] prohibition[,] and limit[s] prosecutorial
discretion.” Gonzales v. Carhart, 550 U. S. 124, 149, 150
(2007). The scienter requirement in this statute does not,
as McFadden suggests, render the statute vague. More-
over, to the extent McFadden suggests that the substantial
similarity test for defining analogues is itself indetermi-
nate, his proposed alternative scienter requirement would
do nothing to cure that infirmity.
                            III
  The District Court’s instructions to the jury did not fully
convey the mental state required by the Analogue Act.
The jury was instructed only that McFadden had to
“knowingly and intentionally distribut[e] a mixture or
substance that has an actual, intended, or claimed stimu-
lant, depressant, or hallucinogenic effect on the central
nervous system” substantially similar to that of a con-
trolled substance. App. 40.
  The Government contends that any error in the jury
instructions was harmless because no rational jury could
have concluded that McFadden was unaware that the
substances he was distributing were controlled. We have
                 Cite as: 576 U. S. ____ (2015)           11

                     Opinion of the Court

recognized that even the omission of an element from a
jury charge is subject to harmless-error analysis. Neder v.
United States, 527 U. S. 1, 15 (1999). Because the Court of
Appeals did not address that issue, we remand for that
court to consider it in the first instance.
                        *     *    *
  For the foregoing reasons, we vacate the judgment of the
Court of Appeals and remand the case for further proceed-
ings consistent with this opinion.
                                            It is so ordered.
                 Cite as: 576 U. S. ____ (2015)            1

                   Opinion of ROBERTS, C. J.

SUPREME COURT OF THE UNITED STATES
                         _________________

                          No. 14–378
                         _________________


 STEPHEN DOMINICK MCFADDEN, PETITIONER v.

             UNITED STATES

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

           APPEALS FOR THE FOURTH CIRCUIT

                        [June 18, 2015] 


  CHIEF JUSTICE ROBERTS, concurring in part and concur-
ring in the judgment.
  I join the Court’s opinion, except to the extent that it
says the Government can satisfy the mental state re-
quirement of Section 841(a)(1) “by showing that the de-
fendant knew the identity of the substance he possessed.”
Ante, at 5. Section 841(a)(1) makes it “unlawful for any
person knowingly . . . to manufacture, distribute, or dis-
pense . . . a controlled substance.” As the Court points out,
the word “knowingly” applies “not just to the statute’s
verbs, but also to the object of those verbs—‘a controlled
substance.’ ” Ante, at 4 (emphasis deleted). That suggests
that a defendant needs to know more than the identity of
the substance; he needs to know that the substance is
controlled. See, e.g., United States v. Howard, 773 F. 3d
519, 526 (CA4 2014); United States v. Washington, 596
F. 3d 926, 944 (CA8 2010); United States v. Rogers, 387
F. 3d 925, 935 (CA7 2004).
  In cases involving well-known drugs such as heroin, a
defendant’s knowledge of the identity of the substance can
be compelling evidence that he knows the substance is
controlled. See United States v. Turcotte, 405 F. 3d 515,
525 (CA7 2005). But that is not necessarily true for lesser
known drugs. A pop quiz for any reader who doubts the
point: Two drugs—dextromethorphan and hydrocodone—
2                     MCFADDEN v. UNITED STATES

                          Opinion of ROBERTS, C. J.

are both used as cough suppressants. They are also both
used as recreational drugs. Which one is a controlled
substance?*
   The Court says that knowledge of the substance’s iden-
tity suffices because “ignorance of the law is typically no
defense to criminal prosecution.” Ante, at 5. I agree that
is “typically” true. But when “there is a legal element in
the definition of the offense,” a person’s lack of knowledge
regarding that legal element can be a defense. Liparota v.
United States, 471 U. S. 419, 425, n. 9 (1985). And here,
there is arguably a legal element in Section 841(a)(1)—
that the substance be “controlled.”
   The analogy the Court drew in Liparota was to a charge
of receipt of stolen property: It is no defense that the
defendant did not know such receipt was illegal, but it is a
defense that he did not know the property was stolen.
Here, the argument goes, it is no defense that a defendant
did not know it was illegal to possess a controlled sub-
stance, but it is a defense that he did not know the sub-
stance was controlled.
   Ultimately, the Court’s statements on this issue are not
necessary to its conclusion that the District Court’s jury
instructions “did not fully convey the mental state re-
quired by the Analogue Act.” Ante, at 10. Those state-
ments should therefore not be regarded as controlling if
the issue arises in a future case.




——————
    *   The answer is hydrocodone.
