(Slip Opinion)              OCTOBER TERM, 2009                                       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

  HOLDER, ATTORNEY GENERAL, ET AL. v. HUMANI-

           TARIAN LAW PROJECT ET AL. 


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

   No. 08–1498. Argued February 23, 2010—Decided June 21, 2010*
It is a federal crime to “knowingly provid[e] material support or re
  sources to a foreign terrorist organization.” 18 U. S. C. §2339B(a)(1).
  The authority to designate an entity a “foreign terrorist organization”
  rests with the Secretary of State, and is subject to judicial review.
  “[T]he term ‘material support or resources’ means any property, tan
  gible or intangible, or service, including currency or monetary in
  struments or financial securities, financial services, lodging, training,
  expert advice or assistance, safehouses, false documentation or iden
  tification, communications equipment, facilities, weapons, lethal sub
  stances, explosives, personnel (1 or more individuals who may be or
  include oneself), and transportation, except medicine or religious ma
  terials.” §2339A(b)(1). Over the years, §2339B and the definition of
  “material support or resources” have been amended, inter alia, to
  clarify that a violation requires knowledge of the foreign group’s des
  ignation as a terrorist organization or its commission of terrorist acts,
  §2339B(a)(1); and to define the terms “training,” §2339A(b)(2), “ex
  pert advice or assistance,” §2339A(b)(3), and “personnel,” §2339B(h).
     Among the entities the Secretary of State has designated “foreign
  terrorist organization[s]” are the Partiya Karkeran Kurdistan (PKK)
  and the Liberation Tigers of Tamil Eelam (LTTE), which aim to es
  tablish independent states for, respectively, Kurds in Turkey and
  Tamils in Sri Lanka. Although both groups engage in political and
  humanitarian activities, each has also committed numerous terrorist
  attacks, some of which have harmed American citizens. Claiming
——————
  * Together with No. 09–89, Humanitarian Law Project et al. v.
Holder, Attorney General, et al., also on certiorari to the same court.
2             HOLDER v. HUMANITARIAN LAW PROJECT

                                  Syllabus

    they wish to support those groups’ lawful, nonviolent activities, two
    U. S. citizens and six domestic organizations (hereinafter plaintiffs)
    initiated this constitutional challenge to the material-support stat
    ute. The litigation has had a complicated 12-year history. Ulti
    mately, the District Court partially enjoined the enforcement of the
    material-support statute against plaintiffs. After the Ninth Circuit
    affirmed, plaintiffs and the Government cross-petitioned for certio
    rari. The Court granted both petitions.
       As the litigation now stands, plaintiffs challenge §2339B’s prohibi
    tion on providing four types of material support—“training,” “expert
    advice or assistance,” “service,” and “personnel”—asserting violations
    of the Fifth Amendment’s Due Process Clause on the ground that the
    statutory terms are impermissibly vague, and violations of their First
    Amendment rights to freedom of speech and association. They claim
    that §2339B is invalid to the extent it prohibits them from engaging
    in certain specified activities, including training PKK members to use
    international law to resolve disputes peacefully; teaching PKK mem
    bers to petition the United Nations and other representative bodies
    for relief; and engaging in political advocacy on behalf of Kurds living
    in Turkey and Tamils living in Sri Lanka.
Held: The material-support statute, §2339B, is constitutional as applied
 to the particular forms of support that plaintiffs seek to provide to
 foreign terrorist organizations. Pp. 8–36.
    (a) This preenforcement challenge to §2339B is a justiciable Article
 III case or controversy. Plaintiffs face “a credible threat of prosecu
 tion” and “should not be required to await and undergo a criminal
 prosecution as the sole means of seeking relief.” Babbitt v. Farm
 Workers, 442 U. S. 289, 298. P. 10.
    (b) The Court cannot avoid the constitutional issues in this litiga
 tion by accepting plaintiffs’ argument that the material-support stat
 ute, when applied to speech, should be interpreted to require proof
 that a defendant intended to further a foreign terrorist organization’s
 illegal activities. That reading is inconsistent with §2339B’s text,
 which prohibits “knowingly” providing material support and demon
 strates that Congress chose knowledge about the organization’s con
 nection to terrorism, not specific intent to further its terrorist activi
 ties, as the necessary mental state for a violation. Plaintiffs’ reading
 is also untenable in light of the sections immediately surrounding
 §2339B, which—unlike §2339B—do refer to intent to further terrorist
 activity. See §§2339A(a), 2339C(a)(1). Finally, there is no textual
 basis for plaintiffs’ argument that the same language in §2339B
 should be read to require specific intent with regard to speech, but
 not with regard to other forms of material support. Pp. 10–12.
    (c) As applied to plaintiffs, the material-support statute is not un
                    Cite as: 561 U. S. ____ (2010)                      3

                               Syllabus

constitutionally vague. The Ninth Circuit improperly merged plain
tiffs’ vagueness challenge with their First Amendment claims, hold
ing that “training,” “service,” and a portion of “expert advice or assis
tance” were impermissibly vague because they applied to protected
speech—regardless of whether those applications were clear. The
Court of Appeals also contravened the rule that “[a] plaintiff who en
gages in some conduct that is clearly proscribed cannot complain of
the vagueness of the law as applied to the conduct of others.” Hoff
man Estates v. Flipside, Hoffman Estates, Inc., 455 U. S. 489, 495.
   The material-support statute, in its application to plaintiffs, “pro
vide[s] a person of ordinary intelligence fair notice of what is prohib
ited.” United States v. Williams, 553 U. S. 285, 304. The statutory
terms at issue here—“training,” “expert advice or assistance,” “ser
vice,” and “personnel”—are quite different from the sorts of terms,
like “ ‘annoying’ ” and “ ‘indecent,’ ” that the Court has struck down for
requiring “wholly subjective judgments without statutory definitions,
narrowing context, or settled legal meanings.” Id., at 306. Congress
has increased the clarity of §2339B’s terms by adding narrowing
definitions, and §2339B’s knowledge requirement further reduces any
potential for vagueness, see Hill v. Colorado, 530 U. S. 703, 732.
   Although the statute may not be clear in every application, the dis
positive point is that its terms are clear in their application to plain
tiffs’ proposed conduct. Most of the activities in which plaintiffs seek
to engage readily fall within the scope of “training” and “expert ad
vice or assistance.” In fact, plaintiffs themselves have repeatedly
used those terms to describe their own proposed activities. Plaintiffs’
resort to hypothetical situations testing the limits of “training” and
“expert advice or assistance” is beside the point because this litiga
tion does not concern such situations. See Scales v. United States,
367 U. S. 203, 223. Gentile v. State Bar of Nev., 501 U. S. 1030,
1049–1051, distinguished. Plaintiffs’ further contention, that the
statute is vague in its application to the political advocacy they wish
to undertake, runs afoul of §2339B(h), which makes clear that “per
sonnel” does not cover advocacy by those acting entirely independ
ently of a foreign terrorist organization, and the ordinary meaning of
“service,” which refers to concerted activity, not independent advo
cacy. Context confirms that meaning: Independently advocating for a
cause is different from the prohibited act of providing a service “to a
foreign terrorist organization.” §2339B(a)(1).
   Thus, any independent advocacy in which plaintiffs wish to engage
is not prohibited by §2339B. On the other hand, a person of ordinary
intelligence would understand the term “service” to cover advocacy
performed in coordination with, or at the direction of, a foreign ter
rorist organization. Plaintiffs argue that this construction of the
4             HOLDER v. HUMANITARIAN LAW PROJECT

                                  Syllabus

    statute poses difficult questions of exactly how much direction or co
    ordination is necessary for an activity to constitute a “service.” Be
    cause plaintiffs have not provided any specific articulation of the de
    gree to which they seek to coordinate their advocacy with the PKK
    and the LTTE, however, they cannot prevail in their preenforcement
    challenge. See Washington State Grange v. Washington State Repub
    lican Party, 552 U. S. 442, 454. Pp. 13–20.
       (d) As applied to plaintiffs, the material-support statute does not
    violate the freedom of speech guaranteed by the First Amendment.
    Pp. 20–34.
         (1) Both plaintiffs and the Government take extreme positions on
    this question. Plaintiffs claim that Congress has banned their pure
    political speech. That claim is unfounded because, under the mate
    rial-support statute, they may say anything they wish on any topic.
    Section 2339B does not prohibit independent advocacy or member
    ship in the PKK and LTTE. Rather, Congress has prohibited “mate
    rial support,” which most often does not take the form of speech. And
    when it does, the statute is carefully drawn to cover only a narrow
    category of speech to, under the direction of, or in coordination with
    foreign groups that the speaker knows to be terrorist organizations.
    On the other hand, the Government errs in arguing that the only
    thing actually at issue here is conduct, not speech, and that the cor
    rect standard of review is intermediate scrutiny, as set out in United
    States v. O’Brien, 391 U. S. 367, 377. That standard is not used to
    review a content-based regulation of speech, and §2339B regulates
    plaintiffs’ speech to the PKK and the LTTE on the basis of its con
    tent. Even if the material-support statute generally functions as a
    regulation of conduct, as applied to plaintiffs the conduct triggering
    coverage under the statute consists of communicating a message.
    Thus, the Court “must [apply] a more demanding standard” than the
    one described in O’Brien. Texas v. Johnson, 491 U. S. 397, 403. Pp.
    20–23.
         (2) The parties agree that the Government’s interest in combat
    ing terrorism is an urgent objective of the highest order, but plaintiffs
    argue that this objective does not justify prohibiting their speech,
    which they say will advance only the legitimate activities of the PKK
    and LTTE. Whether foreign terrorist organizations meaningfully
    segregate support of their legitimate activities from support of terror
    ism is an empirical question. Congress rejected plaintiffs’ position on
    that question when it enacted §2339B, finding that “foreign organiza
    tions that engage in terrorist activity are so tainted by their criminal
    conduct that any contribution to such an organization facilitates that
    conduct.” §301(a), 110 Stat. 1247, note following §2339B. The record
    confirms that Congress was justified in rejecting plaintiffs’ view. The
                   Cite as: 561 U. S. ____ (2010)                      5

                              Syllabus

PKK and the LTTE are deadly groups. It is not difficult to conclude,
as Congress did, that the taint of their violent activities is so great
that working in coordination with them or at their command legiti
mizes and furthers their terrorist means. Moreover, material sup
port meant to promote peaceable, lawful conduct can be diverted to
advance terrorism in multiple ways. The record shows that desig
nated foreign terrorist organizations do not maintain organizational
firewalls between social, political, and terrorist operations, or finan
cial firewalls between funds raised for humanitarian activities and
those used to carry out terrorist attacks. Providing material support
in any form would also undermine cooperative international efforts to
prevent terrorism and strain the United States’ relationships with its
allies, including those that are defending themselves against violent
insurgencies waged by foreign terrorist groups. Pp. 23–28.
     (3) The Court does not rely exclusively on its own factual infer
ences drawn from the record evidence, but considers the Executive
Branch’s stated view that the experience and analysis of Government
agencies charged with combating terrorism strongly support Con
gress’s finding that all contributions to foreign terrorist organiza
tions—even those for seemingly benign purposes—further those
groups’ terrorist activities. That evaluation of the facts, like Con
gress’s assessment, is entitled to deference, given the sensitive na
tional security and foreign relations interests at stake. The Court
does not defer to the Government’s reading of the First Amendment.
But respect for the Government’s factual conclusions is appropriate
in light of the courts’ lack of expertise with respect to national secu
rity and foreign affairs, and the reality that efforts to confront terror
ist threats occur in an area where information can be difficult to ob
tain, the impact of certain conduct can be difficult to assess, and
conclusions must often be based on informed judgment rather than
concrete evidence. The Court also finds it significant that Congress
has been conscious of its own responsibility to consider how its ac
tions may implicate constitutional concerns. Most importantly, Con
gress has avoided any restriction on independent advocacy, or indeed
any activities not directed to, coordinated with, or controlled by for
eign terrorist groups. Given the sensitive interests in national secu
rity and foreign affairs at stake, the political branches have ade
quately substantiated their determination that prohibiting material
support in the form of training, expert advice, personnel, and services
to foreign terrorist groups serves the Government’s interest in pre
venting terrorism, even if those providing the support mean to pro
mote only the groups’ nonviolent ends.
   As to the particular speech plaintiffs propose to undertake, it is
wholly foreseeable that directly training the PKK on how to use in
6             HOLDER v. HUMANITARIAN LAW PROJECT

                                  Syllabus

    ternational law to resolve disputes would provide that group with in
    formation and techniques that it could use as part of a broader strat
    egy to promote terrorism, and to threaten, manipulate, and disrupt.
    Teaching the PKK to petition international bodies for relief also could
    help the PKK obtain funding it would redirect to its violent activities.
    Plaintiffs’ proposals to engage in political advocacy on behalf of
    Kurds and Tamils, in turn, are phrased so generally that they cannot
    prevail in this preenforcement challenge. The Court does not decide
    whether any future applications of the material-support statute to
    speech or advocacy will survive First Amendment scrutiny. It simply
    holds that §2339B does not violate the freedom of speech as applied
    to the particular types of support these plaintiffs seek to provide. Pp.
    28–34.
         (e) Nor does the material-support statute violate plaintiffs’ First
    Amendment freedom of association. Plaintiffs argue that the statute
    criminalizes the mere fact of their associating with the PKK and the
    LTTE, and thereby runs afoul of this Court’s precedents. The Ninth
    Circuit correctly rejected this claim because §2339B does not penalize
    mere association, but prohibits the act of giving foreign terrorist
    groups material support. Any burden on plaintiffs’ freedom of asso
    ciation caused by preventing them from supporting designated for
    eign terrorist organizations, but not other groups, is justified for the
    same reasons the Court rejects their free speech challenge. Pp. 34–
    35.
552 F. 3d 916, affirmed in part, reversed in part, and remanded.

  ROBERTS, C. J., delivered the opinion of the Court, in which STEVENS,
SCALIA, KENNEDY, THOMAS, and ALITO, JJ., joined. BREYER, J., filed a
dissenting opinion, in which GINSBURG and SOTOMAYOR, JJ., joined.
                        Cite as: 561 U. S. ____ (2010)                              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
                                   _________________

                           Nos. 08–1498 and 09–89
                                   _________________


 ERIC H. HOLDER, JR., ATTORNEY GENERAL, ET AL.,
                 PETITIONERS
08–1498                 v.
       HUMANITARIAN LAW PROJECT ET AL.

      HUMANITARIAN LAW PROJECT, ET AL.,
                 PETITIONERS
09–89                   v.
 ERIC H. HOLDER, JR., ATTORNEY GENERAL, ET AL.
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE NINTH CIRCUIT
                                 [June 21, 2010]

   CHIEF JUSTICE ROBERTS delivered the opinion of the
Court.
   Congress has prohibited the provision of “material
support or resources” to certain foreign organizations that
engage in terrorist activity. 18 U. S. C. §2339B(a)(1).
That prohibition is based on a finding that the specified
organizations “are so tainted by their criminal conduct
that any contribution to such an organization facilitates
that conduct.” Antiterrorism and Effective Death Penalty
Act of 1996 (AEDPA), §301(a)(7), 110 Stat. 1247, note
following 18 U. S. C. §2339B (Findings and Purpose). The
plaintiffs in this litigation seek to provide support to two
such organizations. Plaintiffs claim that they seek to
facilitate only the lawful, nonviolent purposes of those
2           HOLDER v. HUMANITARIAN LAW PROJECT

                          Opinion of the Court

groups, and that applying the material-support law to
prevent them from doing so violates the Constitution. In
particular, they claim that the statute is too vague, in
violation of the Fifth Amendment, and that it infringes
their rights to freedom of speech and association, in viola­
tion of the First Amendment. We conclude that the mate­
rial-support statute is constitutional as applied to the
particular activities plaintiffs have told us they wish to
pursue. We do not, however, address the resolution of
more difficult cases that may arise under the statute in
the future.
                             I
   This litigation concerns 18 U. S. C. §2339B, which
makes it a federal crime to “knowingly provid[e] material
support or resources to a foreign terrorist organization.”1
Congress has amended the definition of “material support
or resources” periodically, but at present it is defined as
follows:
       “[T]he term ‘material support or resources’ means any
       property, tangible or intangible, or service, including
       currency or monetary instruments or financial securi­
       ties, financial services, lodging, training, expert advice
       or assistance, safehouses, false documentation or
       identification, communications equipment, facilities,
       weapons, lethal substances, explosives, personnel (1
——————
    1 In
       full, 18 U. S. C. §2339B(a)(1) provides: “UNLAWFUL CONDUCT.—
Whoever knowingly provides material support or resources to a foreign
terrorist organization, or attempts or conspires to do so, shall be fined
under this title or imprisoned not more than 15 years, or both, and, if
the death of any person results, shall be imprisoned for any term of
years or for life. To violate this paragraph, a person must have knowl­
edge that the organization is a designated terrorist organization . . .,
that the organization has engaged or engages in terrorist activity . . .,
or that the organization has engaged or engages in terrorism . . . .” The
terms “terrorist activity” and “terrorism” are defined in 8 U. S. C.
§1182(a)(3)(B)(iii), and 22 U. S. C. §2656f(d)(2), respectively.
                 Cite as: 561 U. S. ____ (2010)           3

                     Opinion of the Court

    or more individuals who may be or include oneself),
    and transportation, except medicine or religious ma­
    terials.” §2339A(b)(1); see also §2339B(g)(4).
  The authority to designate an entity a “foreign terrorist
organization” rests with the Secretary of State. 8 U. S. C.
§§1189(a)(1), (d)(4). She may, in consultation with the
Secretary of the Treasury and the Attorney General, so
designate an organization upon finding that it is foreign,
engages in “terrorist activity” or “terrorism,” and thereby
“threatens the security of United States nationals or the
national security of the United States.” §§1189(a)(1),
(d)(4). “ ‘[N]ational security’ means the national defense,
foreign relations, or economic interests of the United
States.” §1189(d)(2). An entity designated a foreign ter­
rorist organization may seek review of that designation
before the D. C. Circuit within 30 days of that designation.
§1189(c)(1).
  In 1997, the Secretary of State designated 30 groups as
foreign terrorist organizations. See 62 Fed. Reg. 52650.
Two of those groups are the Kurdistan Workers’ Party
(also known as the Partiya Karkeran Kurdistan, or PKK)
and the Liberation Tigers of Tamil Eelam (LTTE). The
PKK is an organization founded in 1974 with the aim of
establishing an independent Kurdish state in southeast­
ern Turkey.       Humanitarian Law Project v. Reno, 9
F. Supp. 2d 1176, 1180–1181 (CD Cal. 1998); Brief for
Petitioners in No. 08–1498, p. 6 (hereinafter Brief for
Government). The LTTE is an organization founded in
1976 for the purpose of creating an independent Tamil
state in Sri Lanka. 9 F. Supp. 2d, at 1182; Brief for Gov­
ernment 6. The District Court in this action found that
the PKK and the LTTE engage in political and humanitar­
ian activities. See 9 F. Supp. 2d, at 1180–1182. The
Government has presented evidence that both groups have
also committed numerous terrorist attacks, some of which
4            HOLDER v. HUMANITARIAN LAW PROJECT

                           Opinion of the Court

have harmed American citizens. See App. 128–133. The
LTTE sought judicial review of its designation as a foreign
terrorist organization; the D. C. Circuit upheld that desig­
nation. See People’s Mojahedin Organization of Iran v.
Dept. of State, 182 F. 3d 17, 18–19, 25 (1999). The PKK
did not challenge its designation. 9 F. Supp. 2d, at 1180.
   Plaintiffs in this litigation are two U. S. citizens and six
domestic organizations: the Humanitarian Law Project
(HLP) (a human rights organization with consultative
status to the United Nations); Ralph Fertig (the HLP’s
president, and a retired administrative law judge); Na­
galingam Jeyalingam (a Tamil physician, born in Sri
Lanka and a naturalized U. S. citizen); and five nonprofit
groups dedicated to the interests of persons of Tamil de­
scent. Brief for Petitioners in No. 09–89, pp. ii, 10 (here­
inafter Brief for Plaintiffs); App. 48. In 1998, plaintiffs
filed suit in federal court challenging the constitutionality
of the material-support statute, §2339B.              Plaintiffs
claimed that they wished to provide support for the hu­
manitarian and political activities of the PKK and the
LTTE in the form of monetary contributions, other tangi­
ble aid, legal training, and political advocacy, but that
they could not do so for fear of prosecution under §2339B.
9 F. Supp. 2d, at 1180–1184.2
   As relevant here, plaintiffs claimed that the material­
——————
   2 At the time plaintiffs first filed suit, 18 U. S. C. §2339B(a) (2000 ed.)

provided: “Whoever, within the United States or subject to the jurisdic­
tion of the United States, knowingly provides material support or
resources to a foreign terrorist organization, or attempts or conspires to
do so, shall be fined under this title or imprisoned not more than 10
years, or both.” See Humanitarian Law Project v. Reno, 9 F. Supp. 2d
1205, 1207 (CD Cal. 1998). And 18 U. S. C. §2339A(b) (2000 ed.)
defined “material support or resources” to mean “currency or other
financial securities, financial services, lodging, training, safehouses,
false documentation or identification, communications equipment,
facilities, weapons, lethal substances, explosives, personnel, transporta­
tion, and other physical assets, except medicine or religious materials.”
                 Cite as: 561 U. S. ____ (2010)            5

                     Opinion of the Court

support statute was unconstitutional on two grounds:
First, it violated their freedom of speech and freedom of
association under the First Amendment, because it crimi­
nalized their provision of material support to the PKK and
the LTTE, without requiring the Government to prove
that plaintiffs had a specific intent to further the unlawful
ends of those organizations. Id., at 1184. Second, plain­
tiffs argued that the statute was unconstitutionally vague.
Id., at 1184–1185.
   Plaintiffs moved for a preliminary injunction, which the
District Court granted in part. The District Court held
that plaintiffs had not established a probability of success
on their First Amendment speech and association claims.
See id., at 1196–1197. But the court held that plaintiffs
had established a probability of success on their claim
that, as applied to them, the statutory terms “personnel”
and “training” in the definition of “material support” were
impermissibly vague. See id., at 1204.
   The Court of Appeals affirmed. 205 F. 3d 1130, 1138
(CA9 2000). The court rejected plaintiffs’ speech and
association claims, including their claim that §2339B
violated the First Amendment in barring them from con­
tributing money to the PKK and the LTTE. See id., at
1133–1136. But the Court of Appeals agreed with the
District Court that the terms “personnel” and “training”
were vague because it was “easy to imagine protected
expression that falls within the bounds” of those terms.
Id., at 1138; see id., at 1137.
   With the preliminary injunction issue decided, the
action returned to the District Court, and the parties
moved for summary judgment on the merits. The District
Court entered a permanent injunction against applying to
plaintiffs the bans on “personnel” and “training” support.
See No. CV–98–1971 ABC (BQRx), 2001 WL 36105333
(CD Cal., Oct. 2, 2001). The Court of Appeals affirmed.
352 F. 3d 382 (CA9 2003).
6         HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

   Meanwhile, in 2001, Congress amended the definition of
“material support or resources” to add the term “expert
advice or assistance.” Uniting and Strengthening America
by Providing Appropriate Tools Required to Intercept and
Obstruct Terrorism Act of 2001 (Patriot Act),
§805(a)(2)(B), 115 Stat. 377. In 2003, plaintiffs filed a
second action challenging the constitutionality of that
term as applied to them. 309 F. Supp. 2d 1185, 1192 (CD
Cal. 2004).
   In that action, the Government argued that plaintiffs
lacked standing and that their preenforcement claims
were not ripe. Id., at 1194. The District Court held that
plaintiffs’ claims were justiciable because plaintiffs had
sufficiently demonstrated a “genuine threat of imminent
prosecution,” id., at 1195 (internal quotation marks omit­
ted), and because §2339B had the potential to chill plain­
tiffs’ protected expression, see id., at 1197–1198. On the
merits, the District Court held that the term “expert ad­
vice or assistance” was impermissibly vague. Id., at 1201.
The District Court rejected, however, plaintiffs’ First
Amendment claims that the new term was substantially
overbroad and criminalized associational speech. See id.,
at 1202, 1203.
   The parties cross-appealed. While the cross-appeals
were pending, the Ninth Circuit granted en banc rehear­
ing of the panel’s 2003 decision in plaintiffs’ first action
(involving the terms “personnel” and “training”). See 382
F. 3d 1154, 1155 (2004). The en banc court heard reargu­
ment on December 14, 2004. See 380 F. Supp. 2d 1134,
1138 (CD Cal. 2005). Three days later, Congress again
amended §2339B and the definition of “material support
or resources.” Intelligence Reform and Terrorism Preven­
tion Act of 2004 (IRTPA), §6603, 118 Stat. 3762–3764.
   In IRTPA, Congress clarified the mental state necessary
to violate §2339B, requiring knowledge of the foreign
group’s designation as a terrorist organization or the
                 Cite as: 561 U. S. ____ (2010)            7

                     Opinion of the Court

group’s commission of terrorist acts. §2339B(a)(1). Con­
gress also added the term “service” to the definition of
“material support or resources,” §2339A(b)(1), and defined
“training” to mean “instruction or teaching designed to
impart a specific skill, as opposed to general knowledge,”
§2339A(b)(2). It also defined “expert advice or assistance”
to mean “advice or assistance derived from scientific,
technical or other specialized knowledge.” §2339A(b)(3).
Finally, IRTPA clarified the scope of the term “personnel”
by providing:
    “No person may be prosecuted under [§2339B] in con­
    nection with the term ‘personnel’ unless that person
    has knowingly provided, attempted to provide, or con­
    spired to provide a foreign terrorist organization with
    1 or more individuals (who may be or include himself)
    to work under that terrorist organization’s direction
    or control or to organize, manage, supervise, or other­
    wise direct the operation of that organization. Indi­
    viduals who act entirely independently of the foreign
    terrorist organization to advance its goals or objec­
    tives shall not be considered to be working under the
    foreign terrorist organization’s direction and control.”
    §2339B(h).
   Shortly after Congress enacted IRTPA, the en banc
Court of Appeals issued an order in plaintiffs’ first action.
393 F. 3d 902, 903 (CA9 2004). The en banc court af­
firmed the rejection of plaintiffs’ First Amendment claims
for the reasons set out in the Ninth Circuit’s panel deci­
sion in 2000. See ibid. In light of IRTPA, however, the en
banc court vacated the panel’s 2003 judgment with respect
to vagueness, and remanded to the District Court for
further proceedings. Ibid. The Ninth Circuit panel as­
signed to the cross-appeals in plaintiffs’ second action
(relating to “expert advice or assistance”) also remanded in
light of IRTPA. See 380 F. Supp. 2d, at 1139.
8         HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

   The District Court consolidated the two actions on re­
mand. See ibid. The court also allowed plaintiffs to chal­
lenge the new term “service.” See id., at 1151, n. 24. The
parties moved for summary judgment, and the District
Court granted partial relief to plaintiffs on vagueness
grounds. See id., at 1156.
   The Court of Appeals affirmed once more. 552 F. 3d
916, 933 (CA9 2009). The court first rejected plaintiffs’
claim that the material-support statute would violate due
process unless it were read to require a specific intent to
further the illegal ends of a foreign terrorist organization.
See id., at 926–927. The Ninth Circuit also held that the
statute was not overbroad in violation of the First
Amendment. See id., at 931–932. As for vagueness, the
Court of Appeals noted that plaintiffs had not raised a
“facial vagueness challenge.” Id., at 929, n. 6. The court
held that, as applied to plaintiffs, the terms “training,”
“expert advice or assistance” (when derived from “other
specialized knowledge”), and “service” were vague because
they “continue[d] to cover constitutionally protected advo­
cacy,” but the term “personnel” was not vague because it
“no longer criminalize[d] pure speech protected by the
First Amendment.” Id., at 929–931.
   The Government petitioned for certiorari, and plaintiffs
filed a conditional cross-petition. We granted both peti­
tions. 557 U. S. ___ (2009).
                             II
  Given the complicated 12-year history of this litigation,
we pause to clarify the questions before us. Plaintiffs
challenge §2339B’s prohibition on four types of material
support—“training,” “expert advice or assistance,” “ser­
vice,” and “personnel.” They raise three constitutional
claims. First, plaintiffs claim that §2339B violates the
Due Process Clause of the Fifth Amendment because these
four statutory terms are impermissibly vague. Second,
                 Cite as: 561 U. S. ____ (2010)            9

                     Opinion of the Court

plaintiffs claim that §2339B violates their freedom of
speech under the First Amendment. Third, plaintiffs
claim that §2339B violates their First Amendment free­
dom of association.
   Plaintiffs do not challenge the above statutory terms in
all their applications. Rather, plaintiffs claim that §2339B
is invalid to the extent it prohibits them from engaging in
certain specified activities. See Brief for Plaintiffs 16–17,
n. 10. With respect to the HLP and Judge Fertig, those
activities are: (1) “train[ing] members of [the] PKK on how
to use humanitarian and international law to peacefully
resolve disputes”; (2) “engag[ing] in political advocacy on
behalf of Kurds who live in Turkey”; and (3) “teach[ing]
PKK members how to petition various representative
bodies such as the United Nations for relief.” 552 F. 3d, at
921, n. 1; see 380 F. Supp. 2d, at 1136. With respect to the
other plaintiffs, those activities are: (1) “train[ing] mem­
bers of [the] LTTE to present claims for tsunami-related
aid to mediators and international bodies”; (2) “offer[ing]
their legal expertise in negotiating peace agreements
between the LTTE and the Sri Lankan government”; and
(3) “engag[ing] in political advocacy on behalf of Tamils
who live in Sri Lanka.” 552 F. 3d, at 921, n. 1; see 380
F. Supp. 2d, at 1137.
   Plaintiffs also state that “the LTTE was recently de­
feated militarily in Sri Lanka,” so “[m]uch of the support
the Tamil organizations and Dr. Jeyalingam sought to
provide is now moot.” Brief for Plaintiffs 11, n. 5. Plain­
tiffs thus seek only to support the LTTE “as a political
organization outside Sri Lanka advocating for the rights of
Tamils.” Ibid. Counsel for plaintiffs specifically stated at
oral argument that plaintiffs no longer seek to teach the
LTTE how to present claims for tsunami-related aid,
because the LTTE now “has no role in Sri Lanka.” Tr. of
Oral Arg. 63. For that reason, helping the LTTE negotiate
a peace agreement with Sri Lanka appears to be moot as
10        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

well. Thus, we do not consider the application of §2339B
to those activities here.
   One last point. Plaintiffs seek preenforcement review of
a criminal statute. Before addressing the merits, we must
be sure that this is a justiciable case or controversy under
Article III. We conclude that it is: Plaintiffs face “a credi­
ble threat of prosecution” and “should not be required to
await and undergo a criminal prosecution as the sole
means of seeking relief.” Babbitt v. Farm Workers, 442
U. S. 289, 298 (1979) (internal quotation marks omitted).
See also MedImmune, Inc. v. Genentech, Inc., 549 U. S.
118, 128–129 (2007).
   Plaintiffs claim that they provided support to the PKK
and the LTTE before the enactment of §2339B and that
they would provide similar support again if the statute’s
allegedly unconstitutional bar were lifted.         See 309
F. Supp. 2d, at 1197. The Government tells us that it has
charged about 150 persons with violating §2339B, and
that several of those prosecutions involved the enforce­
ment of the statutory terms at issue here. See Brief for
Government 5. The Government has not argued to this
Court that plaintiffs will not be prosecuted if they do what
they say they wish to do. Cf. Tr. of Oral Arg. 57–58. See
Babbitt, supra, at 302. See also Milavetz, Gallop & Milav
etz, P. A. v. United States, 559 U. S. ___, ___, ___ (2010)
(slip op., at 4, 19) (considering an as-applied preenforce­
ment challenge brought under the First Amendment).
Based on these considerations, we conclude that plaintiffs’
claims are suitable for judicial review (as one might hope
after 12 years of litigation).
                            III
  Plaintiffs claim, as a threshold matter, that we should
affirm the Court of Appeals without reaching any issues of
constitutional law. They contend that we should interpret
the material-support statute, when applied to speech, to
                  Cite as: 561 U. S. ____ (2010)            11

                      Opinion of the Court

require proof that a defendant intended to further a for­
eign terrorist organization’s illegal activities. That inter­
pretation, they say, would end the litigation because plain­
tiffs’ proposed activities consist of speech, but plaintiffs do
not intend to further unlawful conduct by the PKK or the
LTTE.
   We reject plaintiffs’ interpretation of §2339B because it
is inconsistent with the text of the statute. Section
2339B(a)(1) prohibits “knowingly” providing material
support. It then specifically describes the type of knowl­
edge that is required: “To violate this paragraph, a per­
son must have knowledge that the organization is a
designated terrorist organization . . ., that the organiza­
tion has engaged or engages in terrorist activity . . ., or
that the organization has engaged or engages in terror­
ism. . . .” Ibid. Congress plainly spoke to the necessary
mental state for a violation of §2339B, and it chose
knowledge about the organization’s connection to terror­
ism, not specific intent to further the organization’s
terrorist activities.
   Plaintiffs’ interpretation is also untenable in light of the
sections immediately surrounding §2339B, both of which
do refer to intent to further terrorist activity.           See
§2339A(a) (establishing criminal penalties for one who
“provides material support or resources . . . knowing or
intending that they are to be used in preparation for, or in
carrying out, a violation of” statutes prohibiting violent
terrorist acts); §2339C(a)(1) (setting criminal penalties for
one who “unlawfully and willfully provides or collects
funds with the intention that such funds be used, or with
the knowledge that such funds are to be used, in full or in
part, in order to carry out” other unlawful acts). Congress
enacted §2339A in 1994 and §2339C in 2002.                  See
§120005(a), 108 Stat. 2022 (§2339A); §202(a), 116 Stat.
724 (§2339C). Yet Congress did not import the intent
language of those provisions into §2339B, either when it
12         HOLDER v. HUMANITARIAN LAW PROJECT

                         Opinion of the Court

enacted §2339B in 1996, or when it clarified §2339B’s
knowledge requirement in 2004.
   Finally, plaintiffs give the game away when they argue
that a specific intent requirement should apply only when
the material-support statute applies to speech. There is
no basis whatever in the text of §2339B to read the same
provisions in that statute as requiring intent in some
circumstances but not others. It is therefore clear that
plaintiffs are asking us not to interpret §2339B, but to
revise it. “Although this Court will often strain to con­
strue legislation so as to save it against constitutional
attack, it must not and will not carry this to the point of
perverting the purpose of a statute.” Scales v. United
States, 367 U. S. 203, 211 (1961).
   Scales is the case on which plaintiffs most heavily rely,
but it is readily distinguishable. That case involved the
Smith Act, which prohibited membership in a group advo­
cating the violent overthrow of the government. The
Court held that a person could not be convicted under the
statute unless he had knowledge of the group’s illegal
advocacy and a specific intent to bring about violent over­
throw. Id., at 220–222, 229. This action is different:
Section 2339B does not criminalize mere membership in a
designated foreign terrorist organization. It instead pro­
hibits providing “material support” to such a group. See
infra, at 20–21, 35. Nothing about Scales suggests the
need for a specific intent requirement in such a case. The
Court in Scales, moreover, relied on both statutory text
and precedent that had interpreted closely related provi­
sions of the Smith Act to require specific intent. 367 U. S.,
at 209, 221–222. Plaintiffs point to nothing similar here.
   We cannot avoid the constitutional issues in this litiga­
tion through plaintiffs’ proposed interpretation of §2339B.3
——————
  3 The dissent would interpret the statute along the same lines as the

plaintiffs, to prohibit speech and association “only when the defendant
                      Cite as: 561 U. S. ____ (2010)                     13

                           Opinion of the Court

                             IV
   We turn to the question whether the material-support
statute, as applied to plaintiffs, is impermissibly vague
under the Due Process Clause of the Fifth Amendment.
“A conviction fails to comport with due process if the stat­
ute under which it is obtained fails to provide a person of
ordinary intelligence fair notice of what is prohibited, or is
so standardless that it authorizes or encourages seriously
discriminatory enforcement.” United States v. Williams,
553 U. S. 285, 304 (2008). We consider whether a statute
is vague as applied to the particular facts at issue, for “[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.” Hoffman Estates v.
Flipside, Hoffman Estates, Inc., 455 U. S. 489, 495 (1982).
We have said that when a statute “interferes with the
right of free speech or of association, a more stringent
vagueness test should apply.” Id., at 499. “But ‘perfect
clarity and precise guidance have never been required
even of regulations that restrict expressive activity.’ ”
Williams, supra, at 304 (quoting Ward v. Rock Against
Racism, 491 U. S. 781, 794 (1989)).
   The Court of Appeals did not adhere to these principles.
Instead, the lower court merged plaintiffs’ vagueness
challenge with their First Amendment claims, holding
that portions of the material-support statute were uncon­
——————
knows or intends that those activities will assist the organization’s
unlawful terrorist actions.” Post, at 17 (opinion of BREYER, J.). Accord­
ing to the dissent, this interpretation is “fairly possible” and adopting it
would avoid constitutional concerns. Ibid. (internal quotation marks
omitted). The dissent’s interpretation of §2339B fails for essentially the
same reasons as plaintiffs’. Congress explained what “knowingly”
means in §2339B, and it did not choose the dissent’s interpretation of
that term. In fact, the dissent proposes a mental-state requirement
indistinguishable from the one Congress adopted in §§2339A and
2339C, even though Congress used markedly different language in
§2339B.
14        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

stitutionally vague because they applied to protected
speech—regardless of whether those applications were
clear. The court stated that, even if persons of ordinary
intelligence understood the scope of the term “training,”
that term would “remai[n] impermissibly vague” because
it could “be read to encompass speech and advocacy pro­
tected by the First Amendment.” 552 F. 3d, at 929. It also
found “service” and a portion of “expert advice or assis­
tance” to be vague because those terms covered protected
speech. Id., at 929–930.
   Further, in spite of its own statement that it was not
addressing a “facial vagueness challenge,” id., at 929, n. 6,
the Court of Appeals considered the statute’s application
to facts not before it. Specifically, the Ninth Circuit relied
on the Government’s statement that §2339B would bar
filing an amicus brief in support of a foreign terrorist
organization—which plaintiffs have not told us they wish
to do, and which the Ninth Circuit did not say plaintiffs
wished to do—to conclude that the statute barred pro­
tected advocacy and was therefore vague. See id., at 930.
By deciding how the statute applied in hypothetical cir­
cumstances, the Court of Appeals’ discussion of vagueness
seemed to incorporate elements of First Amendment
overbreadth doctrine. See id., at 929–930 (finding it “easy
to imagine” protected expression that would be barred by
§2339B (internal quotation marks omitted)); id., at 930
(referring to both vagueness and overbreadth).
   In both of these respects, the Court of Appeals contra­
vened the rule that “[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.”
Hoffman Estates, supra, at 495. That rule makes no ex­
ception for conduct in the form of speech. See Parker v.
Levy, 417 U. S. 733, 755–757 (1974). Thus, even to the
extent a heightened vagueness standard applies, a plain­
tiff whose speech is clearly proscribed cannot raise a suc­
                 Cite as: 561 U. S. ____ (2010)           15

                     Opinion of the Court

cessful vagueness claim under the Due Process Clause of
the Fifth Amendment for lack of notice. And he certainly
cannot do so based on the speech of others. Such a plain­
tiff may have a valid overbreadth claim under the First
Amendment, but our precedents make clear that a Fifth
Amendment vagueness challenge does not turn on
whether a law applies to a substantial amount of protected
expression. See Williams, supra, at 304; Hoffman Estates,
supra, at 494–495, 497. Otherwise the doctrines would be
substantially redundant.
   Under a proper analysis, plaintiffs’ claims of vagueness
lack merit. Plaintiffs do not argue that the material­
support statute grants too much enforcement discretion to
the Government. We therefore address only whether the
statute “provide[s] a person of ordinary intelligence fair
notice of what is prohibited.” Williams, 553 U. S., at 304.
   As a general matter, the statutory terms at issue here
are quite different from the sorts of terms that we have
previously declared to be vague. We have in the past
“struck down statutes that tied criminal culpability to
whether the defendant’s conduct was ‘annoying’ or ‘inde­
cent’—wholly subjective judgments without statutory
definitions, narrowing context, or settled legal meanings.”
Id., at 306; see also Papachristou v. Jacksonville, 405 U. S.
156, n. 1 (1972) (holding vague an ordinance that pun­
ished “vagrants,” defined to include “rogues and vaga­
bonds,” “persons who use juggling,” and “common night
walkers” (internal quotation marks omitted)). Applying
the statutory terms in this action—“training,” “expert
advice or assistance,” “service,” and “personnel”—does not
require similarly untethered, subjective judgments.
   Congress also took care to add narrowing definitions to
the material-support statute over time. These definitions
increased the clarity of the statute’s terms.            See
§2339A(b)(2) (“ ‘training’ means instruction or teaching
designed to impart a specific skill, as opposed to general
16        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

knowledge”); §2339A(b)(3) (“ ‘expert advice or assistance’
means advice or assistance derived from scientific, techni­
cal or other specialized knowledge”); §2339B(h) (clarifying
the scope of “personnel”). And the knowledge requirement
of the statute further reduces any potential for vagueness,
as we have held with respect to other statutes containing a
similar requirement. See Hill v. Colorado, 530 U. S. 703,
732 (2000); Posters ‘N’ Things, Ltd. v. United States, 511
U. S. 513, 523, 526 (1994); see also Hoffman Estates, 455
U. S., at 499.
   Of course, the scope of the material-support statute may
not be clear in every application. But the dispositive point
here is that the statutory terms are clear in their applica­
tion to plaintiffs’ proposed conduct, which means that
plaintiffs’ vagueness challenge must fail. Even assuming
that a heightened standard applies because the material­
support statute potentially implicates speech, the statu­
tory terms are not vague as applied to plaintiffs. See
Grayned v. City of Rockford, 408 U. S. 104, 114–115 (1972)
(rejecting a vagueness challenge to a criminal law that
implicated First Amendment activities); Scales, 367 U. S.,
at 223 (same).
   Most of the activities in which plaintiffs seek to engage
readily fall within the scope of the terms “training” and
“expert advice or assistance.” Plaintiffs want to “train
members of [the] PKK on how to use humanitarian and
international law to peacefully resolve disputes,” and
“teach PKK members how to petition various representa­
tive bodies such as the United Nations for relief.” 552
F. 3d, at 921, n. 1. A person of ordinary intelligence would
understand that instruction on resolving disputes through
international law falls within the statute’s definition of
“training” because it imparts a “specific skill,” not “general
knowledge.” §2339A(b)(2). Plaintiffs’ activities also fall
comfortably within the scope of “expert advice or assis­
tance”: A reasonable person would recognize that teaching
                 Cite as: 561 U. S. ____ (2010)           17

                     Opinion of the Court

the PKK how to petition for humanitarian relief before the
United Nations involves advice derived from, as the stat­
ute puts it, “specialized knowledge.” §2339A(b)(3). In fact,
plaintiffs themselves have repeatedly used the terms
“training” and “expert advice” throughout this litigation to
describe their own proposed activities, demonstrating that
these common terms readily and naturally cover plaintiffs’
conduct. See, e.g., Brief for Plaintiffs 10, 11; App. 56, 58,
59, 61, 62, 63, 80, 81, 98, 99, 106, 107, 117.
   Plaintiffs respond by pointing to hypothetical situations
designed to test the limits of “training” and “expert advice
or assistance.” They argue that the statutory definitions
of these terms use words of degree—like “specific,” “gen­
eral,” and “specialized”—and that it is difficult to apply
those definitions in particular cases. See Brief for Plain­
tiffs 27 (debating whether teaching a course on geography
would constitute training); id., at 29. And they cite Gen
tile v. State Bar of Nev., 501 U. S. 1030 (1991), in which we
found vague a state bar rule providing that a lawyer in a
criminal case, when speaking to the press, “may state
without elaboration . . . the general nature of the . . .
defense.” Id., at 1048 (internal quotation marks omitted).
   Whatever force these arguments might have in the
abstract, they are beside the point here. Plaintiffs do not
propose to teach a course on geography, and cannot seek
refuge in imaginary cases that straddle the boundary
between “specific skills” and “general knowledge.” See
Parker v. Levy, 417 U. S., at 756. We emphasized this
point in Scales, holding that even if there might be theo­
retical doubts regarding the distinction between “active”
and “nominal” membership in an organization—also terms
of degree—the defendant’s vagueness challenge failed
because his “case present[ed] no such problem.” 367 U. S.,
at 223.
   Gentile was different. There the asserted vagueness in
a state bar rule was directly implicated by the facts before
18        HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

the Court: Counsel had reason to suppose that his particu­
lar statements to the press would not violate the rule, yet
he was disciplined nonetheless. See 501 U. S., at 1049–
1051. We did not suggest that counsel could escape disci­
pline on vagueness grounds if his own speech were plainly
prohibited.
   Plaintiffs also contend that they want to engage in
“political advocacy” on behalf of Kurds living in Turkey
and Tamils living in Sri Lanka. 552 F. 3d, at 921, n. 1.
They are concerned that such advocacy might be regarded
as “material support” in the form of providing “personnel”
or “service[s],” and assert that the statute is unconstitu­
tionally vague because they cannot tell.
   As for “personnel,” Congress enacted a limiting defini­
tion in IRTPA that answers plaintiffs’ vagueness concerns.
Providing material support that constitutes “personnel” is
defined as knowingly providing a person “to work under
that terrorist organization’s direction or control or to
organize, manage, supervise, or otherwise direct the op­
eration of that organization.” §2339B(h). The statute
makes clear that “personnel” does not cover independent
advocacy: “Individuals who act entirely independently of
the foreign terrorist organization to advance its goals or
objectives shall not be considered to be working under the
foreign terrorist organization’s direction and control.”
Ibid.
   “[S]ervice” similarly refers to concerted activity, not
independent advocacy. See Webster’s Third New Interna­
tional Dictionary 2075 (1993) (defining “service” to mean
“the performance of work commanded or paid for by an­
other: a servant’s duty: attendance on a superior”; or “an
act done for the benefit or at the command of another”).
Context confirms that ordinary meaning here. The statute
prohibits providing a service “to a foreign terrorist organi­
zation.” §2339B(a)(1) (emphasis added). The use of the
word “to” indicates a connection between the service and
                 Cite as: 561 U. S. ____ (2010)           19

                     Opinion of the Court

the foreign group. We think a person of ordinary intelli­
gence would understand that independently advocating for
a cause is different from providing a service to a group
that is advocating for that cause.
   Moreover, if independent activity in support of a terror­
ist group could be characterized as a “service,” the stat­
ute’s specific exclusion of independent activity in the
definition of “personnel” would not make sense. Congress
would not have prohibited under “service” what it specifi­
cally exempted from prohibition under “personnel.” The
other types of material support listed in the statute, in­
cluding “lodging,” “weapons,” “explosives,” and “transpor­
tation,” §2339A(b)(1), are not forms of support that could
be provided independently of a foreign terrorist organiza­
tion. We interpret “service” along the same lines. Thus,
any independent advocacy in which plaintiffs wish to
engage is not prohibited by §2339B. On the other hand, a
person of ordinary intelligence would understand the term
“service” to cover advocacy performed in coordination with,
or at the direction of, a foreign terrorist organization.
   Plaintiffs argue that this construction of the statute
poses difficult questions of exactly how much direction or
coordination is necessary for an activity to constitute a
“service.” See Reply Brief for Petitioners in No. 09–89,
p. 14 (hereinafter Reply Brief for Plaintiffs) (“Would any
communication with any member be sufficient? With a
leader? Must the ‘relationship’ have any formal elements,
such as an employment or contractual relationship? What
about a relationship through an intermediary?”). The
problem with these questions is that they are entirely
hypothetical. Plaintiffs have not provided any specific
articulation of the degree to which they seek to coordinate
their advocacy with the PKK and the LTTE. They have
instead described the form of their intended advocacy only
in the most general terms. See, e.g., Brief for Plaintiffs
10–11 (plaintiffs “would like, among other things, to offer
20        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

their services to advocate on behalf of the rights of the
Kurdish people and the PKK before the United Nations
and the United States Congress” (internal quotation
marks and alteration omitted)); App. 59 (plaintiffs would
like to “write and distribute publications supportive of the
PKK and the cause of Kurdish liberation” and “advocate
for the freedom of political prisoners in Turkey”).
   Deciding whether activities described at such a level of
generality would constitute prohibited “service[s]” under
the statute would require “sheer speculation”—which
means that plaintiffs cannot prevail in their preenforce­
ment challenge. See Washington State Grange v. Wash
ington State Republican Party, 552 U. S. 442, 454 (2008).
It is apparent with respect to these claims that “grada­
tions of fact or charge would make a difference as to
criminal liability,” and so “adjudication of the reach and
constitutionality of [the statute] must await a concrete fact
situation.” Zemel v. Rusk, 381 U. S. 1, 20 (1965).
                              V

                              A

  We next consider whether the material-support statute,
as applied to plaintiffs, violates the freedom of speech
guaranteed by the First Amendment. Both plaintiffs and
the Government take extreme positions on this question.
Plaintiffs claim that Congress has banned their “pure
political speech.” E.g., Brief for Plaintiffs 2, 25, 43. It has
not. Under the material-support statute, plaintiffs may
say anything they wish on any topic. They may speak and
write freely about the PKK and LTTE, the governments of
Turkey and Sri Lanka, human rights, and international
law. They may advocate before the United Nations. As
the Government states: “The statute does not prohibit
independent advocacy or expression of any kind.” Brief for
Government 13. Section 2339B also “does not prevent
[plaintiffs] from becoming members of the PKK and LTTE
                     Cite as: 561 U. S. ____ (2010)                   21

                          Opinion of the Court

or impose any sanction on them for doing so.” Id., at 60.
Congress has not, therefore, sought to suppress ideas or
opinions in the form of “pure political speech.” Rather,
Congress has prohibited “material support,” which most
often does not take the form of speech at all. And when it
does, the statute is carefully drawn to cover only a narrow
category of speech to, under the direction of, or in coordi­
nation with foreign groups that the speaker knows to be
terrorist organizations.4
   For its part, the Government takes the foregoing too far,
claiming that the only thing truly at issue in this litigation
is conduct, not speech. Section 2339B is directed at the
fact of plaintiffs’ interaction with the PKK and LTTE, the
Government contends, and only incidentally burdens their
expression. The Government argues that the proper
standard of review is therefore the one set out in United
States v. O’Brien, 391 U. S. 367 (1968). In that case, the
Court rejected a First Amendment challenge to a convic­
tion under a generally applicable prohibition on destroying
draft cards, even though O’Brien had burned his card in
protest against the draft. See id., at 370, 376, 382. In so
doing, we applied what we have since called “intermediate
scrutiny,” under which a “content-neutral regulation will
be sustained under the First Amendment if it advances
important governmental interests unrelated to the sup­
pression of free speech and does not burden substantially
more speech than necessary to further those interests.”
Turner Broadcasting System, Inc. v. FCC, 520 U. S. 180,
189 (1997) (citing O’Brien, supra, at 377).
   The Government is wrong that the only thing actually at
——————
  4 The dissent also analyzes the statute as if it prohibited “[p]eaceful

political advocacy” or “pure speech and association,” without more.
Post, at 9, 17. Section 2339B does not do that, and we do not address
the constitutionality of any such prohibitions. The dissent’s claim that
our decision is inconsistent with this Court’s cases analyzing those
sorts of restrictions, post, at 11–12, is accordingly unfounded.
22         HOLDER v. HUMANITARIAN LAW PROJECT

                         Opinion of the Court

issue in this litigation is conduct, and therefore wrong to
argue that O’Brien provides the correct standard of re­
view.5 O’Brien does not provide the applicable standard
for reviewing a content-based regulation of speech, see
R. A. V. v. St. Paul, 505 U. S. 377, 385–386 (1992); Texas
v. Johnson, 491 U. S. 397, 403, 406–407 (1989), and
§2339B regulates speech on the basis of its content. Plain­
tiffs want to speak to the PKK and the LTTE, and whether
they may do so under §2339B depends on what they say.
If plaintiffs’ speech to those groups imparts a “specific
skill” or communicates advice derived from “specialized
knowledge”—for example, training on the use of interna­
tional law or advice on petitioning the United Nations—
then it is barred. See Brief for Government 33–34. On the
other hand, plaintiffs’ speech is not barred if it imparts
only general or unspecialized knowledge. See id., at 32.
   The Government argues that §2339B should nonethe­
less receive intermediate scrutiny because it generally
functions as a regulation of conduct. That argument runs
headlong into a number of our precedents, most promi­
nently Cohen v. California, 403 U. S. 15 (1971). Cohen
also involved a generally applicable regulation of conduct,
barring breaches of the peace. See id., at 16. But when
Cohen was convicted for wearing a jacket bearing an
epithet, we did not apply O’Brien. See 403 U. S., at 16, 18.
Instead, we recognized that the generally applicable law
——————
  5 The  Government suggests in passing that, to the extent plaintiffs’
activities constitute speech, that speech is wholly unprotected by the
First Amendment. The Government briefly analogizes speech coordi­
nated with foreign terrorist organizations to speech effecting a crime,
like the words that constitute a conspiracy. Brief for Government 46;
Reply Brief for Government 31–32, and n. 8. See, e.g., Giboney v.
Empire Storage & Ice Co., 336 U. S. 490, 498, 502 (1949). We do not
consider any such argument because the Government does not develop
it: The Government’s submission is that applying §2339B to plaintiffs
triggers intermediate First Amendment scrutiny—not that it triggers
no First Amendment scrutiny at all.
                 Cite as: 561 U. S. ____ (2010)           23

                     Opinion of the Court

was directed at Cohen because of what his speech commu­
nicated—he violated the breach of the peace statute be­
cause of the offensive content of his particular message.
We accordingly applied more rigorous scrutiny and re­
versed his conviction. See id., at 18–19, 26.
   This suit falls into the same category. The law here
may be described as directed at conduct, as the law in
Cohen was directed at breaches of the peace, but as ap­
plied to plaintiffs the conduct triggering coverage under
the statute consists of communicating a message. As we
explained in Texas v. Johnson: “If the [Government’s]
regulation is not related to expression, then the less strin­
gent standard we announced in United States v. O’Brien
for regulations of noncommunicative conduct controls. If
it is, then we are outside of O’Brien’s test, and we must
[apply] a more demanding standard.” 491 U. S., at 403
(citation omitted).
                              B
   The First Amendment issue before us is more refined
than either plaintiffs or the Government would have it. It
is not whether the Government may prohibit pure political
speech, or may prohibit material support in the form of
conduct. It is instead whether the Government may pro­
hibit what plaintiffs want to do—provide material support
to the PKK and LTTE in the form of speech.
   Everyone agrees that the Government’s interest in
combating terrorism is an urgent objective of the highest
order. See Brief for Plaintiffs 51. Plaintiffs’ complaint is
that the ban on material support, applied to what they
wish to do, is not “necessary to further that interest.”
Ibid. The objective of combating terrorism does not justify
prohibiting their speech, plaintiffs argue, because their
support will advance only the legitimate activities of the
designated terrorist organizations, not their terrorism.
Id., at 51–52.
24        HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

   Whether foreign terrorist organizations meaningfully
segregate support of their legitimate activities from sup­
port of terrorism is an empirical question. When it en­
acted §2339B in 1996, Congress made specific findings
regarding the serious threat posed by international terror­
ism. See AEDPA §§301(a)(1)–(7), 110 Stat. 1247, note
following 18 U. S. C. §2339B (Findings and Purpose). One
of those findings explicitly rejects plaintiffs’ contention
that their support would not further the terrorist activities
of the PKK and LTTE: “[F]oreign organizations that en­
gage in terrorist activity are so tainted by their criminal
conduct that any contribution to such an organization
facilitates that conduct.” §301(a)(7) (emphasis added).
   Plaintiffs argue that the reference to “any contribution”
in this finding meant only monetary support. There is no
reason to read the finding to be so limited, particularly
because Congress expressly prohibited so much more than
monetary support in §2339B. Congress’s use of the term
“contribution” is best read to reflect a determination that
any form of material support furnished “to” a foreign
terrorist organization should be barred, which is precisely
what the material-support statute does. Indeed, when
Congress enacted §2339B, Congress simultaneously re­
moved an exception that had existed in §2339A(a) (1994
ed.) for the provision of material support in the form of
“humanitarian assistance to persons not directly involved
in” terrorist activity. AEDPA §323, 110 Stat. 1255; 205
F. 3d, at 1136. That repeal demonstrates that Congress
considered and rejected the view that ostensibly peaceful
aid would have no harmful effects.
   We are convinced that Congress was justified in reject­
ing that view. The PKK and the LTTE are deadly groups.
“The PKK’s insurgency has claimed more than 22,000
lives.” Declaration of Kenneth R. McKune, App. 128, ¶5.
The LTTE has engaged in extensive suicide bombings and
political assassinations, including killings of the Sri
                 Cite as: 561 U. S. ____ (2010)           25

                     Opinion of the Court

Lankan President, Security Minister, and Deputy Defense
Minister. Id., at 130–132; Brief for Government 6–7. “On
January 31, 1996, the LTTE exploded a truck bomb filled
with an estimated 1,000 pounds of explosives at the Cen­
tral Bank in Colombo, killing 100 people and injuring
more than 1,400. This bombing was the most deadly
terrorist incident in the world in 1996.” McKune Affida­
vit, App. 131, ¶6.h. It is not difficult to conclude as Con­
gress did that the “tain[t]” of such violent activities is so
great that working in coordination with or at the com­
mand of the PKK and LTTE serves to legitimize and
further their terrorist means. AEDPA §301(a)(7), 110
Stat. 1247.
   Material support meant to “promot[e] peaceable, lawful
conduct,” Brief for Plaintiffs 51, can further terrorism by
foreign groups in multiple ways. “Material support” is a
valuable resource by definition. Such support frees up
other resources within the organization that may be put to
violent ends. It also importantly helps lend legitimacy to
foreign terrorist groups—legitimacy that makes it easier
for those groups to persist, to recruit members, and to
raise funds—all of which facilitate more terrorist attacks.
“Terrorist organizations do not maintain organizational
‘firewalls’ that would prevent or deter . . . sharing and
commingling of support and benefits.” McKune Affidavit,
App. 135, ¶11. “[I]nvestigators have revealed how terror­
ist groups systematically conceal their activities behind
charitable, social, and political fronts.” M. Levitt, Hamas:
Politics, Charity, and Terrorism in the Service of Jihad 2–
3 (2006). “Indeed, some designated foreign terrorist or­
ganizations use social and political components to recruit
personnel to carry out terrorist operations, and to provide
support to criminal terrorists and their families in aid of
such operations.” McKune Affidavit, App. 135, ¶11;
Levitt, supra, at 2 (“Muddying the waters between its
political activism, good works, and terrorist attacks,
26        HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

Hamas is able to use its overt political and charitable
organizations as a financial and logistical support network
for its terrorist operations”).
   Money is fungible, and “[w]hen foreign terrorist organi­
zations that have a dual structure raise funds, they high­
light the civilian and humanitarian ends to which such
moneys could be put.” McKune Affidavit, App. 134, ¶9.
But “there is reason to believe that foreign terrorist or­
ganizations do not maintain legitimate financial firewalls
between those funds raised for civil, nonviolent activities,
and those ultimately used to support violent, terrorist
operations.” Id., at 135, ¶12. Thus, “[f]unds raised osten­
sibly for charitable purposes have in the past been redi­
rected by some terrorist groups to fund the purchase of
arms and explosives.” Id., at 134, ¶10. See also Brief for
Anti-Defamation League as Amicus Curiae 19–29 (describ­
ing fundraising activities by the PKK, LTTE, and Hamas);
Regan v. Wald, 468 U. S. 222, 243 (1984) (upholding Presi­
dent’s decision to impose travel ban to Cuba “to curtail the
flow of hard currency to Cuba—currency that could then
be used in support of Cuban adventurism”). There is
evidence that the PKK and the LTTE, in particular, have
not “respected the line between humanitarian and violent
activities.” McKune Affidavit, App. 135, ¶13 (discussing
PKK); see id., at 134 (LTTE).
   The dissent argues that there is “no natural stopping
place” for the proposition that aiding a foreign terrorist
organization’s lawful activity promotes the terrorist or­
ganization as a whole. Post, at 10. But Congress has
settled on just such a natural stopping place: The statute
reaches only material support coordinated with or under
the direction of a designated foreign terrorist organization.
Independent advocacy that might be viewed as promoting
the group’s legitimacy is not covered. See supra, at 18–
                      Cite as: 561 U. S. ____ (2010)                    27

                          Opinion of the Court

21.6
   Providing foreign terrorist groups with material support
in any form also furthers terrorism by straining the
United States’ relationships with its allies and undermin­
ing cooperative efforts between nations to prevent terror­
ist attacks. We see no reason to question Congress’s find­
ing that “international cooperation is required for an
effective response to terrorism, as demonstrated by the
numerous multilateral conventions in force providing
universal prosecutive jurisdiction over persons involved in
a variety of terrorist acts, including hostage taking, mur­
der of an internationally protected person, and aircraft
piracy and sabotage.” AEDPA §301(a)(5), 110 Stat. 1247,
note following 18 U. S. C. §2339B (Findings and Purpose).
The material-support statute furthers this international
effort by prohibiting aid for foreign terrorist groups that
harm the United States’ partners abroad: “A number of
designated foreign terrorist organizations have attacked
moderate governments with which the United States has
vigorously endeavored to maintain close and friendly
relations,” and those attacks “threaten [the] social, eco­
nomic and political stability” of such governments.
McKune Affidavit, App. 137, ¶16. “[O]ther foreign terror­
ist organizations attack our NATO allies, thereby impli­
cating important and sensitive multilateral security ar­
rangements.” Ibid.
   For example, the Republic of Turkey—a fellow member
of NATO—is defending itself against a violent insurgency
——————
  6 The dissent also contends that the particular sort of material sup­
port plaintiffs seek to provide cannot be diverted to terrorist activities,
in the same direct way as funds or goods. Post, at 8–9. This contention
misses the point. Both common sense and the evidence submitted by
the Government make clear that material support of a terrorist group’s
lawful activities facilitates the group’s ability to attract “funds,” “fi­
nancing,” and “goods” that will further its terrorist acts. See McKune
Affidavit, App. 134–136.
28        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

waged by the PKK. Brief for Government 6; App. 128.
That nation and our other allies would react sharply to
Americans furnishing material support to foreign groups
like the PKK, and would hardly be mollified by the expla­
nation that the support was meant only to further those
groups’ “legitimate” activities. From Turkey’s perspective,
there likely are no such activities. See 352 F. 3d, at 389
(observing that Turkey prohibits membership in the PKK
and prosecutes those who provide support to that group,
regardless of whether the support is directed to lawful
activities).
                              C
  In analyzing whether it is possible in practice to distin­
guish material support for a foreign terrorist group’s
violent activities and its nonviolent activities, we do not
rely exclusively on our own inferences drawn from the
record evidence. We have before us an affidavit stating
the Executive Branch’s conclusion on that question. The
State Department informs us that “[t]he experience and
analysis of the U. S. government agencies charged with
combating terrorism strongly suppor[t]” Congress’s finding
that all contributions to foreign terrorist organizations
further their terrorism. McKune Affidavit, App. 133, ¶8.
See Winter v. Natural Resources Defense Council, Inc., 555
U. S. ___, ___ (2008) (slip op., at 14–15) (looking to similar
affidavits to support according weight to national security
claims). In the Executive’s view: “Given the purposes,
organizational structure, and clandestine nature of foreign
terrorist organizations, it is highly likely that any mate­
rial support to these organizations will ultimately inure to
the benefit of their criminal, terrorist functions—
regardless of whether such support was ostensibly in­
tended to support non-violent, non-terrorist activities.”
McKune Affidavit, App. 133, ¶8.
  That evaluation of the facts by the Executive, like Con­
                  Cite as: 561 U. S. ____ (2010)           29

                      Opinion of the Court

gress’s assessment, is entitled to deference. This litigation
implicates sensitive and weighty interests of national
security and foreign affairs. The PKK and the LTTE have
committed terrorist acts against American citizens abroad,
and the material-support statute addresses acute foreign
policy concerns involving relationships with our Nation’s
allies. See id., at 128–133, 137. We have noted that “nei­
ther the Members of this Court nor most federal judges
begin the day with briefings that may describe new and
serious threats to our Nation and its people.” Boumediene
v. Bush, 553 U. S. 723, 797 (2008). It is vital in this con­
text “not to substitute . . . our own evaluation of evidence
for a reasonable evaluation by the Legislative Branch.”
Rostker v. Goldberg, 453 U. S. 57, 68 (1981). See Wald,
468 U. S., at 242; Haig v. Agee, 453 U. S. 280, 292 (1981).
   Our precedents, old and new, make clear that concerns
of national security and foreign relations do not warrant
abdication of the judicial role. We do not defer to the
Government’s reading of the First Amendment, even when
such interests are at stake. We are one with the dissent
that the Government’s “authority and expertise in these
matters do not automatically trump the Court’s own obli­
gation to secure the protection that the Constitution
grants to individuals.” Post, at 23. But when it comes to
collecting evidence and drawing factual inferences in this
area, “the lack of competence on the part of the courts is
marked,” Rostker, supra, at 65, and respect for the Gov­
ernment’s conclusions is appropriate.
   One reason for that respect is that national security and
foreign policy concerns arise in connection with efforts to
confront evolving threats in an area where information
can be difficult to obtain and the impact of certain conduct
difficult to assess. The dissent slights these real con­
straints in demanding hard proof—with “detail,” “specific
facts,” and “specific evidence”—that plaintiffs’ proposed
activities will support terrorist attacks. See post, at 9, 16,
30        HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

23. That would be a dangerous requirement. In this
context, conclusions must often be based on informed
judgment rather than concrete evidence, and that reality
affects what we may reasonably insist on from the Gov­
ernment. The material-support statute is, on its face, a
preventive measure—it criminalizes not terrorist attacks
themselves, but aid that makes the attacks more likely to
occur. The Government, when seeking to prevent immi­
nent harms in the context of international affairs and
national security, is not required to conclusively link all
the pieces in the puzzle before we grant weight to its
empirical conclusions. See Zemel v. Rusk, 381 U. S., at 17
(“[B]ecause of the changeable and explosive nature of
contemporary international relations, . . . Congress . . .
must of necessity paint with a brush broader than that it
customarily wields in domestic areas”).
   This context is different from that in decisions like
Cohen. In that case, the application of the statute turned
on the offensiveness of the speech at issue. Observing that
“one man’s vulgarity is another’s lyric,” we invalidated
Cohen’s conviction in part because we concluded that
“governmental officials cannot make principled distinc­
tions in this area.” 403 U. S., at 25. In this litigation, by
contrast, Congress and the Executive are uniquely posi­
tioned to make principled distinctions between activities
that will further terrorist conduct and undermine United
States foreign policy, and those that will not.
   We also find it significant that Congress has been con­
scious of its own responsibility to consider how its actions
may implicate constitutional concerns. First, §2339B only
applies to designated foreign terrorist organizations.
There is, and always has been, a limited number of those
organizations designated by the Executive Branch, see,
e.g., 74 Fed. Reg. 29742 (2009); 62 Fed. Reg. 52650 (1997),
and any groups so designated may seek judicial review of
the designation. Second, in response to the lower courts’
                 Cite as: 561 U. S. ____ (2010)           31

                     Opinion of the Court

holdings in this litigation, Congress added clarity to the
statute by providing narrowing definitions of the terms
“training,” “personnel,” and “expert advice or assistance,”
as well as an explanation of the knowledge required to
violate §2339B. Third, in effectuating its stated intent not
to abridge First Amendment rights, see §2339B(i), Con­
gress has also displayed a careful balancing of interests in
creating limited exceptions to the ban on material support.
The definition of material support, for example, excludes
medicine and religious materials. See §2339A(b)(1). In
this area perhaps more than any other, the Legislature’s
superior capacity for weighing competing interests means
that “we must be particularly careful not to substitute our
judgment of what is desirable for that of Congress.” Rost
ker, supra, at 68. Finally, and most importantly, Congress
has avoided any restriction on independent advocacy, or
indeed any activities not directed to, coordinated with, or
controlled by foreign terrorist groups.
  At bottom, plaintiffs simply disagree with the consid­
ered judgment of Congress and the Executive that provid­
ing material support to a designated foreign terrorist
organization—even seemingly benign support—bolsters
the terrorist activities of that organization. That judg­
ment, however, is entitled to significant weight, and we
have persuasive evidence before us to sustain it. Given
the sensitive interests in national security and foreign
affairs at stake, the political branches have adequately
substantiated their determination that, to serve the Gov­
ernment’s interest in preventing terrorism, it was neces­
sary to prohibit providing material support in the form of
training, expert advice, personnel, and services to foreign
terrorist groups, even if the supporters meant to promote
only the groups’ nonviolent ends.
  We turn to the particular speech plaintiffs propose to
undertake. First, plaintiffs propose to “train members of
[the] PKK on how to use humanitarian and international
32        HOLDER v. HUMANITARIAN LAW PROJECT

                     Opinion of the Court

law to peacefully resolve disputes.” 552 F. 3d, at 921, n. 1.
Congress can, consistent with the First Amendment,
prohibit this direct training. It is wholly foreseeable that
the PKK could use the “specific skill[s]” that plaintiffs
propose to impart, §2339A(b)(2), as part of a broader
strategy to promote terrorism. The PKK could, for exam­
ple, pursue peaceful negotiation as a means of buying time
to recover from short-term setbacks, lulling opponents into
complacency, and ultimately preparing for renewed at­
tacks. See generally A. Marcus, Blood and Belief: The
PKK and the Kurdish Fight for Independence 286–295
(2007) (describing the PKK’s suspension of armed struggle
and subsequent return to violence). A foreign terrorist
organization introduced to the structures of the interna­
tional legal system might use the information to threaten,
manipulate, and disrupt. This possibility is real, not
remote.
   Second, plaintiffs propose to “teach PKK members how
to petition various representative bodies such as the
United Nations for relief.” 552 F. 3d, at 921, n. 1. The
Government acts within First Amendment strictures in
banning this proposed speech because it teaches the or­
ganization how to acquire “relief,” which plaintiffs never
define with any specificity, and which could readily in­
clude monetary aid. See Brief for Plaintiffs 10–11, 16–17,
n. 10; App. 58–59, 80–81. Indeed, earlier in this litigation,
plaintiffs sought to teach the LTTE “to present claims for
tsunami-related aid to mediators and international bod­
ies,” 552 F. 3d, at 921, n. 1, which naturally included
monetary relief. Money is fungible, supra, at 26, and
Congress logically concluded that money a terrorist group
such as the PKK obtains using the techniques plaintiffs
propose to teach could be redirected to funding the group’s
violent activities.
   Finally, plaintiffs propose to “engage in political advo­
cacy on behalf of Kurds who live in Turkey,” and “engage
                  Cite as: 561 U. S. ____ (2010)            33

                      Opinion of the Court

in political advocacy on behalf of Tamils who live in Sri
Lanka.” 552 F. 3d, at 921, n. 1. As explained above, su
pra, at 19–20, plaintiffs do not specify their expected level
of coordination with the PKK or LTTE or suggest what
exactly their “advocacy” would consist of. Plaintiffs’ pro­
posals are phrased at such a high level of generality that
they cannot prevail in this preenforcement challenge. See
supra, at 20; Grange, 552 U. S., at 454; Zemel, 381 U. S.,
at 20.
   In responding to the foregoing, the dissent fails to ad­
dress the real dangers at stake. It instead considers only
the possible benefits of plaintiffs’ proposed activities in the
abstract. See post, at 13–15. The dissent seems unwilling
to entertain the prospect that training and advising a
designated foreign terrorist organization on how to take
advantage of international entities might benefit that
organization in a way that facilitates its terrorist activi­
ties. In the dissent’s world, such training is all to the
good. Congress and the Executive, however, have con­
cluded that we live in a different world: one in which the
designated foreign terrorist organizations “are so tainted
by their criminal conduct that any contribution to such an
organization facilitates that conduct.” AEDPA §301(a)(7).
One in which, for example, “the United Nations High
Commissioner for Refugees was forced to close a Kurdish
refugee camp in northern Iraq because the camp had come
under the control of the PKK, and the PKK had failed to
respect its ‘neutral and humanitarian nature.’ ” McKune
Affidavit, App. 135–136, ¶13. Training and advice on how
to work with the United Nations could readily have helped
the PKK in its efforts to use the United Nations camp as a
base for terrorist activities.
   If only good can come from training our adversaries in
international dispute resolution, presumably it would
have been unconstitutional to prevent American citizens
from training the Japanese Government on using interna­
34        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

tional organizations and mechanisms to resolve disputes
during World War II. It would, under the dissent’s rea­
soning, have been contrary to our commitment to resolving
disputes through “ ‘deliberative forces,’ ” post, at 13 (quot­
ing Whitney v. California, 274 U. S. 357, 375 (1927)
(Brandeis, J., concurring)), for Congress to conclude that
assisting Japan on that front might facilitate its war effort
more generally. That view is not one the First Amend­
ment requires us to embrace.
   All this is not to say that any future applications of the
material-support statute to speech or advocacy will sur­
vive First Amendment scrutiny. It is also not to say that
any other statute relating to speech and terrorism would
satisfy the First Amendment. In particular, we in no way
suggest that a regulation of independent speech would
pass constitutional muster, even if the Government were
to show that such speech benefits foreign terrorist organi­
zations. We also do not suggest that Congress could ex­
tend the same prohibition on material support at issue
here to domestic organizations. We simply hold that, in
prohibiting the particular forms of support that plaintiffs
seek to provide to foreign terrorist groups, §2339B does
not violate the freedom of speech.
                              VI
  Plaintiffs’ final claim is that the material-support stat­
ute violates their freedom of association under the First
Amendment. Plaintiffs argue that the statute criminal­
izes the mere fact of their associating with the PKK and
the LTTE, thereby running afoul of decisions like De
Jonge v. Oregon, 299 U. S. 353 (1937), and cases in which
we have overturned sanctions for joining the Communist
Party, see, e.g., Keyishian v. Board of Regents of Univ. of
State of N. Y., 385 U. S. 589 (1967); United States v. Robel,
389 U. S. 258 (1967).
  The Court of Appeals correctly rejected this claim be­
                  Cite as: 561 U. S. ____ (2010)           35

                      Opinion of the Court

cause the statute does not penalize mere association with
a foreign terrorist organization. As the Ninth Circuit put
it: “The statute does not prohibit being a member of one of
the designated groups or vigorously promoting and sup­
porting the political goals of the group. . . . What [§2339B]
prohibits is the act of giving material support . . . .” 205
F. 3d, at 1133. Plaintiffs want to do the latter. Our deci­
sions scrutinizing penalties on simple association or as­
sembly are therefore inapposite. See, e.g., Robel, supra, at
262 (“It is precisely because th[e] statute sweeps indis­
criminately across all types of association with Commu­
nist-action groups, without regard to the quality and
degree of membership, that it runs afoul of the First
Amendment”); De Jonge, supra, at 362.
   Plaintiffs also argue that the material-support statute
burdens their freedom of association because it prevents
them from providing support to designated foreign terror­
ist organizations, but not to other groups. See Brief for
Plaintiffs 56; Reply Brief for Plaintiffs 37–38. Any burden
on plaintiffs’ freedom of association in this regard is justi­
fied for the same reasons that we have denied plaintiffs’
free speech challenge. It would be strange if the Constitu­
tion permitted Congress to prohibit certain forms of
speech that constitute material support, but did not per­
mit Congress to prohibit that support only to particularly
dangerous and lawless foreign organizations. Congress is
not required to ban material support to every group or
none at all.
                        *   *    *
  The Preamble to the Constitution proclaims that the
people of the United States ordained and established that
charter of government in part to “provide for the common
defence.” As Madison explained, “[s]ecurity against for­
eign danger is . . . an avowed and essential object of the
American Union.” The Federalist No. 41, p. 269 (J. Cooke
36        HOLDER v. HUMANITARIAN LAW PROJECT

                      Opinion of the Court

ed. 1961). We hold that, in regulating the particular forms
of support that plaintiffs seek to provide to foreign terror­
ist organizations, Congress has pursued that objective
consistent with the limitations of the First and Fifth
Amendments.
   The judgment of the United States Court of Appeals for
the Ninth Circuit is affirmed in part and reversed in part,
and the cases are remanded for further proceedings con­
sistent with this opinion.
                                             It is so ordered.
                 Cite as: 561 U. S. ____ (2010)          1

                    BREYER, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                   Nos. 08–1498 and 09–89
                         _________________


 ERIC H. HOLDER, JR., ATTORNEY GENERAL, ET AL.,
                 PETITIONERS
08–1498                 v.
       HUMANITARIAN LAW PROJECT ET AL.

      HUMANITARIAN LAW PROJECT, ET AL.,
                 PETITIONERS
09–89                   v.
 ERIC H. HOLDER, JR., ATTORNEY GENERAL, ET AL.
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
            APPEALS FOR THE NINTH CIRCUIT
                        [June 21, 2010]

   JUSTICE BREYER, with whom JUSTICES GINSBURG and
SOTOMAYOR join, dissenting.
   Like the Court, and substantially for the reasons it
gives, I do not think this statute is unconstitutionally
vague. But I cannot agree with the Court’s conclusion
that the Constitution permits the Government to prose
cute the plaintiffs criminally for engaging in coordinated
teaching and advocacy furthering the designated organiza
tions’ lawful political objectives. In my view, the Govern
ment has not met its burden of showing that an interpre
tation of the statute that would prohibit this speech- and
association-related activity serves the Government’s com
pelling interest in combating terrorism. And I would
interpret the statute as normally placing activity of this
kind outside its scope. See Crowell v. Benson, 285 U. S.
22, 62 (1932); Ashwander v. TVA, 297 U. S. 288, 346–347
(1936) (Brandeis, J., concurring).
2         HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

                               I
   The statute before us forbids “knowingly provid[ing]” “a
foreign terrorist organization” with “material support or
resources,” defined to include, among other things, “train
ing,” “expert advice or assistance,” “personnel,” and “ser
vice.” 18 U. S. C. §§2339B(a)(1), (g)(4); §2339A(b)(1). The
Secretary of State has designated the Kurdistan Workers’
Party (PKK) and the Liberation Tigers of Tamil Eelam
(LTTE) as “foreign terrorist organizations”—a designation
authorized where the organization is “foreign,” threatens
the security of the United States or its nationals, and
engages in “terrorist activity,” defined to include “any” of
such activities as “highjacking” and “assassination,” or the
“use of . . . any . . . weapon or dangerous device . . . with
intent to endanger, directly or indirectly, the safety of one
or more individuals.” 62 Fed. Reg. 52650 (1997); 8 U. S. C.
§1182(a)(3)(B)(iii); 18 U. S. C. §2339B(a)(1).
   The plaintiffs, all United States citizens or associations,
now seek an injunction and declaration providing that,
without violating the statute, they can (1) “train members
of [the] PKK on how to use humanitarian and interna
tional law to peacefully resolve disputes”; (2) “engage in
political advocacy on behalf of Kurds who live in Turkey”;
(3) “teach PKK members how to petition various represen
tative bodies such as the United Nations for relief”; and (4)
“engage in political advocacy on behalf of Tamils who live
in Sri Lanka.” Humanitarian Law Project v. Mukasey, 552
F. 3d 916, 921, n. 1 (CA9 2009); ante, at 9. All these ac
tivities are of a kind that the First Amendment ordinarily
protects.
   In my view, the Government has not made the strong
showing necessary to justify under the First Amendment
the criminal prosecution of those who engage in these
activities. All the activities involve the communication
and advocacy of political ideas and lawful means of achiev
ing political ends. Even the subjects the plaintiffs wish to
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                     BREYER, J., dissenting

teach—using international law to resolve disputes peace
fully or petitioning the United Nations, for instance—
concern political speech. We cannot avoid the constitu
tional significance of these facts on the basis that some of
this speech takes place outside the United States and is
directed at foreign governments, for the activities also
involve advocacy in this country directed to our govern
ment and its policies. The plaintiffs, for example, wish to
write and distribute publications and to speak before the
United States Congress. App. 58–59.
   That this speech and association for political purposes is
the kind of activity to which the First Amendment ordi
narily offers its strongest protection is elementary. See
New York Times Co. v. Sullivan, 376 U. S. 254, 269 (1964)
(The First Amendment “ ‘was fashioned to assure unfet
tered interchange of ideas for the bringing about of politi
cal and social changes desired by the people’ ” (quoting
Roth v. United States, 354 U. S. 476, 484 (1957)); Lovell v.
City of Griffin, 303 U. S. 444, 452 (1938) (rejecting licens
ing scheme for distribution of “pamphlets and leaflets,”
“historic weapons in the defense of liberty”); R. A. V. v. St.
Paul, 505 U. S. 377, 422 (1992) (STEVENS, J., concurring in
judgment) (“Our First Amendment decisions have created
a rough hierarchy in the constitutional protection of
speech” in which “[c]ore political speech occupies the high
est, most protected position”); Hill v. Colorado, 530 U. S.
703, 787 (2000) (KENNEDY, J., dissenting) (“Laws punish
ing speech which protests the lawfulness or morality of the
government’s own policy are the essence of the tyrannical
power the First Amendment guards against”); Citizens
United v. Federal Election Comm’n, 558 U. S. ___, ___
(2010) (slip op., at 33) (“If the First Amendment has any
force, it prohibits Congress from fining or jailing citizens,
or associations of citizens, for simply engaging in political
speech”).
   Although in the Court’s view the statute applies only
4         HOLDER v. HUMANITARIAN LAW PROJECT

                    BREYER, J., dissenting

where the PKK helps to coordinate a defendant’s activi
ties, ante, at 21, the simple fact of “coordination” alone
cannot readily remove protection that the First Amend
ment would otherwise grant. That amendment, after all,
also protects the freedom of association. See NAACP v.
Claiborne Hardware Co., 458 U. S. 886, 911 (1982) (The
First Amendment’s protections “of speech, assembly,
association, and petition, ‘though not identical, are insepa
rable’ ” (quoting Thomas v. Collins, 323 U. S. 516, 530
(1945))); De Jonge v. Oregon, 299 U. S. 353, 364 (1937)
(describing the “right of peaceable assembly” as “a right
cognate to those of free speech and free presses and . . .
equally fundamental”); see also Roberts v. United States
Jaycees, 468 U. S. 609, 622 (1984). “Coordination” with a
political group, like membership, involves association.
   “Coordination” with a group that engages in unlawful
activity also does not deprive the plaintiffs of the First
Amendment’s protection under any traditional “categori
cal” exception to its protection. The plaintiffs do not pro
pose to solicit a crime. They will not engage in fraud or
defamation or circulate obscenity. Cf. United States v.
Stevens, 559 U. S. ___ , ___ (2010) (slip op., at 5–6) (de
scribing “categories” of unprotected speech). And the First
Amendment protects advocacy even of unlawful action so
long as that advocacy is not “directed to inciting or produc
ing imminent lawless action and . . . likely to incite or
produce such action.” Brandenburg v. Ohio, 395 U. S. 444,
447 (1969) (per curiam) (emphasis added). Here the plain
tiffs seek to advocate peaceful, lawful action to secure
political ends; and they seek to teach others how to do
the same. No one contends that the plaintiffs’ speech to
these organizations can be prohibited as incitement under
Brandenburg.
   Moreover, the Court has previously held that a person
who associates with a group that uses unlawful means to
achieve its ends does not thereby necessarily forfeit the
                  Cite as: 561 U. S. ____ (2010)             5

                     BREYER, J., dissenting

First Amendment’s protection for freedom of association.
See Scales v. United States, 367 U. S. 203, 229 (1961)
(“[Q]uasi-political parties or other groups that may em
brace both legal and illegal aims differ from a technical
conspiracy, which is defined by its criminal purpose”); see
also NAACP, supra, at 908 (“The right to associate does
not lose all constitutional protection merely because some
members of the group may have participated in conduct or
advocated doctrine that itself is not protected”). Rather,
the Court has pointed out in respect to associating with a
group advocating overthrow of the Government through
force and violence: “If the persons assembling have com
mitted crimes elsewhere . . . , they may be prosecuted for
their . . . violation of valid laws. But it is a different mat
ter when the State, instead of prosecuting them for such
offenses, seizes upon mere participation in a peaceable
assembly and a lawful public discussion as the basis for a
criminal charge.” De Jonge, supra, at 365 (striking down
conviction for attending and assisting at Communist Party
meeting because “[n]otwithstanding [the party’s] objec
tives, the defendant still enjoyed his personal right of free
speech and to take part in peaceable assembly having a
lawful purpose”).
   Not even the “serious and deadly problem” of interna
tional terrorism can require automatic forfeiture of First
Amendment rights. §301(a)(1), 110 Stat. 1247, note fol
lowing 18 U. S. C. §2339B. Cf. §2339B(i) (instructing
courts not to “constru[e] or appl[y the statute] so as to
abridge the exercise of right guaranteed under the First
Amendment”). After all, this Court has recognized that
not “ ‘[e]ven the war power . . . remove[s] constitutional
limitations safeguarding essential liberties.’ ”         United
States v. Robel, 389 U. S. 258, 264 (1967) (quoting Home
Building & Loan Assn. v. Blaisdell, 290 U. S. 398, 426
(1934)). See also Abrams v. United States, 250 U. S. 616,
628 (1919) (Holmes, J., dissenting) (“[A]s against dangers
6         HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

peculiar to war, as against others, the principle of the
right to free speech is always the same”). Thus, there is
no general First Amendment exception that applies here.
If the statute is constitutional in this context, it would
have to come with a strong justification attached.
  It is not surprising that the majority, in determining the
constitutionality of criminally prohibiting the plaintiffs’
proposed activities, would apply, not the kind of interme
diate First Amendment standard that applies to conduct,
but “ ‘a more demanding standard.’ ” Ante, at 23 (quoting
Texas v. Johnson, 491 U. S. 397, 403 (1989)). Indeed,
where, as here, a statute applies criminal penalties and at
least arguably does so on the basis of content-based dis
tinctions, I should think we would scrutinize the statute
and justifications “strictly”—to determine whether the
prohibition is justified by a “compelling” need that cannot
be “less restrictively” accommodated. See Houston v. Hill,
482 U. S. 451, 459 (1987) (criminal penalties); Ashcroft v.
American Civil Liberties Union, 535 U. S. 564, 573 (2002)
(content-based); Simon & Schuster, Inc. v. Members of N.
Y. State Crime Victims Bd., 502 U. S. 105, 118 (1991)
(same); Consolidated Edison Co. of N. Y. v. Public Serv.
Comm’n of N. Y., 447 U. S. 530, 540 (1980) (strict scru
tiny); First Nat. Bank of Boston v. Bellotti, 435 U. S. 765,
786 (1978) (same).
  But, even if we assume for argument’s sake that “strict
scrutiny” does not apply, no one can deny that we must at
the very least “measure the validity of the means adopted
by Congress against both the goal it has sought to achieve
and the specific prohibitions of the First Amendment.”
Robel, supra, 268, n. 20 (describing constitutional task
where the Court is faced “with a clear conflict between a
federal statute enacted in the interests of national security
and an individual’s exercise of his First Amendment
rights”). And here I need go no further, for I doubt that
the statute, as the Government would interpret it, can
                 Cite as: 561 U. S. ____ (2010)            7

                     BREYER, J., dissenting

survive any reasonably applicable First Amendment stan
dard. See, e.g., Turner Broadcasting System, Inc. v. FCC,
520 U. S. 180, 189 (1997) (describing intermediate scru
tiny). Cf. Nixon v. Shrink Missouri Government PAC, 528
U. S. 377, 402 (2000) (BREYER, J., concurring) (examining
whether a statute worked speech-related harm “out of
proportion to the statute’s salutary effects upon” other
interests).

   The Government does identify a compelling countervail
ing interest, namely, the interest in protecting the security
of the United States and its nationals from the threats
that foreign terrorist organizations pose by denying those
organizations financial and other fungible resources. I do
not dispute the importance of this interest. But I do dis
pute whether the interest can justify the statute’s criminal
prohibition. To put the matter more specifically, precisely
how does application of the statute to the protected activi
ties before us help achieve that important security-related
end? See Simon & Schuster, 502 U. S., at 118 (requiring
that “narrowly drawn” means further a “compelling state
interest” by the least restrictive means (internal quotation
marks omitted)); Turner, supra, at 189 (requiring “ad
vance[ment of] important governmental interests unre
lated to the suppression of free speech” without “bur
den[ing] substantially more speech than necessary to
further those interests”); Robel, supra, at 268, n. 20 (re
quiring measurement of the “means adopted by Congress
against . . . the [security] goal it has sought to achieve”).
See also Nixon, 528 U. S., at 402 (BREYER, J., concurring);
Federal Election Comm’n v. Wisconsin Right to Life, Inc.,
551 U. S. 449, 478 (2007) (opinion of ROBERTS, C. J.) (“A
court . . . must ensure that [the interest justifying a stat
utory restriction] supports each application of [the]
statute”).
   The Government makes two efforts to answer this ques
8         HOLDER v. HUMANITARIAN LAW PROJECT

                    BREYER, J., dissenting

tion. First, the Government says that the plaintiffs’ sup
port for these organizations is “fungible” in the same sense
as other forms of banned support. Being fungible, the
plaintiffs’ support could, for example, free up other re
sources, which the organization might put to terrorist
ends. Brief for Respondents in No. 09–89, pp. 54–56 (here
inafter Government Brief).
   The proposition that the two very different kinds of
“support” are “fungible,” however, is not obviously true.
There is no obvious way in which undertaking advocacy
for political change through peaceful means or teaching
the PKK and LTTE, say, how to petition the United Na
tions for political change is fungible with other resources
that might be put to more sinister ends in the way that
donations of money, food, or computer training are fungi
ble. It is far from obvious that these advocacy activities
can themselves be redirected, or will free other resources
that can be directed, towards terrorist ends. Thus, we
must determine whether the Government has come for
ward with evidence to support its claim.
   The Government has provided us with no empirical
information that might convincingly support this claim.
Instead, the Government cites only to evidence that Con
gress was concerned about the “fungible” nature in general
of resources, predominately money and material goods. It
points to a congressional finding that “foreign organiza
tions that engage in terrorist activity are so tainted by
their criminal conduct that any contribution to such an
organization facilitates that conduct.” §301(a)(7), 110
Stat. 1247, note following 18 U. S. C. §2339B (emphasis
added). It also points to a House Report’s statement that
“supply[ing] funds, goods, or services” would “hel[p] defray
the cost to the terrorist organization of running the osten
sibly legitimate activities,” and “in turn fre[e] an equal
sum that can then be spent on terrorist activities.” H. R.
Rep. No. 104–383, p. 81 (1995) (emphasis added). Finally,
                 Cite as: 561 U. S. ____ (2010)            9

                     BREYER, J., dissenting

the Government refers to a State Department official’s
affidavit describing how ostensibly charitable contribu
tions have either been “redirected” to terrorist ends or,
even if spent charitably, have “unencumber[ed] funds
raised from other sources for use in facilitating violent,
terrorist activities and gaining political support for these
activities.” Declaration of Kenneth R. McKune, App. 134,
136 (emphasis added).
   The most one can say in the Government’s favor about
these statements is that they might be read as offering
highly general support for its argument. The statements
do not, however, explain in any detail how the plaintiffs’
political-advocacy-related activities might actually be
“fungible” and therefore capable of being diverted to ter
rorist use. Nor do they indicate that Congress itself was
concerned with “support” of this kind. The affidavit refers
to “funds,” “financing,” and “goods”—none of which en
compasses the plaintiffs’ activities. Ibid. The statutory
statement and the House Report use broad terms like
“contributions” and “services” that might be construed as
encompassing the plaintiffs’ activities. But in context,
those terms are more naturally understood as referring to
contributions of goods, money, or training and other ser
vices (say, computer programming) that could be diverted
to, or free funding for, terrorist ends. See infra, at 15–16.
Peaceful political advocacy does not obviously fall into
these categories. And the statute itself suggests that
Congress did not intend to curtail freedom of speech or
association. See §2339B(i) (“Nothing in this section shall
be construed or applied so as to abridge the exercise of
rights guaranteed under the First Amendment”); see also
infra, at 18–19.
   Second, the Government says that the plaintiffs’ pro
posed activities will “bolste[r] a terrorist organization’s
efficacy and strength in a community” and “undermin[e]
this nation’s efforts to delegitimize and weaken those
10        HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

groups.” Government Brief 56 (emphasis added). In the
Court’s view, too, the Constitution permits application of
the statute to activities of the kind at issue in part because
those activities could provide a group that engages in
terrorism with “legitimacy.” Ante, at 25. The Court sug
gests that, armed with this greater “legitimacy,” these
organizations will more readily be able to obtain material
support of the kinds Congress plainly intended to ban—
money, arms, lodging, and the like. See ibid.
   Yet the Government does not claim that the statute
forbids any speech “legitimating” a terrorist group.
Rather, it reads the statute as permitting (1) membership
in terrorist organizations, (2) “peaceably assembling with
members of the PKK and LTTE for lawful discussion,” or
(3) “independent advocacy” on behalf of these organiza
tions. Government Brief 66, 61, 13. The Court, too, em
phasizes that activities not “coordinated with” the terror
ist groups are not banned. See ante, at 21, 26, 31
(emphasis added). And it argues that speaking, writing,
and teaching aimed at furthering a terrorist organization’s
peaceful political ends could “mak[e] it easier for those
groups to persist, to recruit members, and to raise funds.”
Ante, at 25.
   But this “legitimacy” justification cannot by itself war
rant suppression of political speech, advocacy, and asso
ciation. Speech, association, and related activities on
behalf of a group will often, perhaps always, help to le
gitimate that group. Thus, were the law to accept a “le
gitimating” effect, in and of itself and without qualifica
tion, as providing sufficient grounds for imposing such a
ban, the First Amendment battle would be lost in untold
instances where it should be won. Once one accepts this
argument, there is no natural stopping place. The argu
ment applies as strongly to “independent” as to “coordi
nated” advocacy. But see ante, at 26–27. That fact is
reflected in part in the Government’s claim that the ban
                 Cite as: 561 U. S. ____ (2010)           11

                     BREYER, J., dissenting

here, so supported, prohibits a lawyer hired by a desig
nated group from filing on behalf of that group an amicus
brief before the United Nations or even before this Court.
See Tr. of Oral Arg. 47–49, 53.
   That fact is also reflected in the difficulty of drawing a
line designed to accept the legitimacy argument in some
instances but not in others. It is inordinately difficult to
distinguish when speech activity will and when it will not
initiate the chain of causation the Court suggests—a chain
that leads from peaceful advocacy to “legitimacy” to in
creased support for the group to an increased supply of
material goods that support its terrorist activities. Even
were we to find some such line of distinction, its applica
tion would seem so inherently uncertain that it would
often, perhaps always, “chill” protected speech beyond its
boundary. In short, the justification, put forward simply
in abstract terms and without limitation, must always, or
it will never, be sufficient. Given the nature of the plain
tiffs’ activities, “always” cannot possibly be the First
Amendment’s answer.
   Regardless, the “legitimacy” justification itself is incon
sistent with critically important First Amendment case
law. Consider the cases involving the protection the First
Amendment offered those who joined the Communist
Party intending only to further its peaceful activities. In
those cases, this Court took account of congressional find
ings that the Communist Party not only advocated theo
retically but also sought to put into practice the overthrow
of our Government through force and violence. The Court
had previously accepted Congress’ determinations that the
American Communist Party was a “Communist action
organization” which (1) acted under the “control, direction,
and discipline” of the world Communist movement, a
movement that sought to employ “espionage, sabotage,
terrorism, and any other means deemed necessary, to
establish a Communist totalitarian dictatorship,” and (2)
12        HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

“endeavor[ed]” to bring about “the overthrow of existing
governments by . . . force if necessary.” Communist Party
of United States v. Subversive Activities Control Bd., 367
U. S. 1, 5–6 (1961) (internal quotation marks omitted).
   Nonetheless, the Court held that the First Amendment
protected an American’s right to belong to that party—
despite whatever “legitimating” effect membership might
have had—as long as the person did not share the party’s
unlawful purposes. See, e.g., De Jonge, 299 U. S. 353;
Scales, 367 U. S., at 228–230; Elfbrandt v. Russell, 384
U. S. 11, 17 (1966); Keyishian v. Board of Regents of Univ.
of State of N. Y., 385 U. S. 589, 605–610 (1967); Robel, 389
U. S. 258 (holding that national security interests did not
justify overbroad criminal prohibition on members of
Communist-affiliated organizations working in any de
fense-related facility). As I have pointed out, those cases
draw further support from other cases permitting pure
advocacy of even the most unlawful activity—as long as
that advocacy is not “directed to inciting or producing
imminent lawless action and . . . likely to incite or produce
such action.” Brandenburg, 395 U. S., at 447. The Gov
ernment’s “legitimating” theory would seem to apply to
these cases with equal justifying force; and, if recognized,
it would have led this Court to conclusions other than
those it reached.

   Nor can the Government overcome these considerations
simply by narrowing the covered activities to those that
involve coordinated, rather than independent, advocacy.
Conversations, discussions, or logistical arrangements
might well prove necessary to carry out the speech-related
activities here at issue (just as conversations and discus
sions are a necessary part of membership in any organiza
tion). The Government does not distinguish this kind of
“coordination” from any other. I am not aware of any form
of words that might be used to describe “coordination” that
                  Cite as: 561 U. S. ____ (2010)           13

                     BREYER, J., dissenting

would not, at a minimum, seriously chill not only the kind
of activities the plaintiffs raise before us, but also the
“independent advocacy” the Government purports to per
mit. And, as for the Government’s willingness to distin
guish independent advocacy from coordinated advocacy,
the former is more likely, not less likely, to confer legiti
macy than the latter. Thus, other things being equal, the
distinction “coordination” makes is arbitrary in respect to
furthering the statute’s purposes. And a rule of law that
finds the “legitimacy” argument adequate in respect to the
latter would have a hard time distinguishing a statute
that sought to attack the former.
   Consider the majority’s development of the Govern
ment’s themes. First, the majority discusses the plaintiffs’
proposal to “ ‘train members of [the] PKK on how to use
humanitarian and international law to peacefully resolve
disputes.’ ” Ante, at 31–32 (quoting 552 F. 3d, at 921, n. 1).
The majority justifies the criminalization of this activity in
significant part on the ground that “peaceful negotia
tion[s]” might just “bu[y] time . . . , lulling opponents into
complacency.” Ante, at 32. And the PKK might use its
new information about “the structures of the international
legal system . . . to threaten, manipulate, and disrupt.”
Ibid.
   What is one to say about these arguments—arguments
that would deny First Amendment protection to the peace
ful teaching of international human rights law on the
ground that a little knowledge about “the international
legal system” is too dangerous a thing; that an opponent’s
subsequent willingness to negotiate might be faked, so
let’s not teach him how to try? What might be said of
these claims by those who live, as we do, in a Nation com
mitted to the resolution of disputes through “deliberative
forces”? Whitney v. California, 274 U. S. 357, 375 (1927)
(Brandeis, J., concurring).
   In my own view, the majority’s arguments stretch the
14        HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

concept of “fungibility” beyond constitutional limits.
Neither Congress nor the Government advanced these
particular hypothetical claims. I am not aware of any case
in this Court—not Gitlow v. New York, 268 U. S. 652
(1925), not Schenck v. United States, 249 U. S. 47 (1919),
not Abrams, 250 U. S. 616, not the later Communist Party
cases decided during the heat of the Cold War—in which
the Court accepted anything like a claim that speech or
teaching might be criminalized lest it, e.g., buy negotiating
time for an opponent who would put that time to bad use.
    Moreover, the risk that those who are taught will put
otherwise innocent speech or knowledge to bad use is
omnipresent, at least where that risk rests on little more
than (even informed) speculation. Hence to accept this
kind of argument without more and to apply it to the
teaching of a subject such as international human rights
law is to adopt a rule of law that, contrary to the Constitu
tion’s text and First Amendment precedent, would auto
matically forbid the teaching of any subject in a case
where national security interests conflict with the First
Amendment. The Constitution does not allow all such
conflicts to be decided in the Government’s favor.
    The majority, as I have said, cannot limit the scope of its
arguments through its claim that the plaintiffs remain
free to engage in the protected activity as long as it is not
“coordinated.” That is because there is no practical way to
organize classes for a group (say, wishing to learn about
human rights law) without “coordination.” Nor can the
majority limit the scope of its argument by pointing to
some special limiting circumstance present here. That is
because the only evidence the majority offers to support its
general claim consists of a single reference to a book about
terrorism, which the Government did not mention, and
which apparently says no more than that at one time the
PKK suspended its armed struggle and then returned to
it.
                  Cite as: 561 U. S. ____ (2010)           15

                     BREYER, J., dissenting

    Second, the majority discusses the plaintiffs’ proposal to
“ ‘teach PKK members how to petition various representa
tive bodies such as the United Nations for relief.’ ” Ante, at
32 (quoting 552 F. 3d, at 921, n. 1; emphasis added). The
majority’s only argument with respect to this proposal is
that the relief obtained “could readily include monetary
aid,” which the PKK might use to buy guns. Ante, at 32.
The majority misunderstands the word “relief.” In this
context, as the record makes clear, the word “relief” does
not refer to “money.” It refers to recognition under the
Geneva Conventions. See App. 57–58 (2003 Complaint);
id., at 79–80 (1998 Complaint); id., at 113 (Fertig Declara
tion); see also Tr. of Oral Arg. 63 (plaintiffs’ counsel deny
ing that plaintiffs seek to teach about obtaining relief in
the form of money).
    Throughout, the majority emphasizes that it would
defer strongly to Congress’ “informed judgment.” See, e.g.,
ante, at 30. But here, there is no evidence that Congress
has made such a judgment regarding the specific activities
at issue in these cases. See infra, at 20–21. In any event,
“whenever the fundamental rights of free speech and
assembly are alleged to have been invaded, it must remain
open [for judicial determination] whether there actually
did exist at the time a clear danger; whether the danger, if
any, was imminent; and whether the evil apprehended
was one so substantial as to justify the stringent restric
tion interposed by the legislature.” Whitney, supra, at
378–379 (Brandeis, J., concurring). In such circum
stances, the “judicial function commands analysis of
whether the specific conduct charged falls within the
reach of the statute and if so whether the legislation is
consonant with the Constitution.” Landmark Communi
cations, Inc. v. Virginia, 435 U. S. 829, 844 (1978). Hence,
a legislative declaration “does not preclude enquiry into
the question whether, at the time and under the circum
stances, the conditions existed which are essential to
16        HOLDER v. HUMANITARIAN LAW PROJECT

                    BREYER, J., dissenting

validity under the Federal Constitution.” Whitney, supra,
at 378; see also Landmark, supra, at 843 (“Deference to a
legislative finding cannot limit judicial inquiry when First
Amendment rights are at stake”).
   I concede that the Government’s expertise in foreign
affairs may warrant deference in respect to many matters,
e.g., our relations with Turkey. Cf. ante, at 27–28. But it
remains for this Court to decide whether the Government
has shown that such an interest justifies criminalizing
speech activity otherwise protected by the First Amend
ment. And the fact that other nations may like us less for
granting that protection cannot in and of itself carry the
day.
   Finally, I would reemphasize that neither the Govern
ment nor the majority points to any specific facts that
show that the speech-related activities before us are fun
gible in some special way or confer some special legitimacy
upon the PKK. Rather, their arguments in this respect
are general and speculative. Those arguments would
apply to virtually all speech-related support for a dual
purpose group’s peaceful activities (irrespective of whether
the speech-related activity is coordinated). Both First
Amendment logic and First Amendment case law prevent
us from “sacrific[ing] First Amendment protections for so
speculative a gain.” Columbia Broadcasting System, Inc.
v. Democratic National Committee, 412 U. S. 94, 127
(1973); see also Consolidated Edison Co., 447 U. S., at 543
(rejecting proffered state interest not supported in record
because “[m]ere speculation of harm does not constitute a
compelling state interest”).
                            II
  For the reasons I have set forth, I believe application of
the statute as the Government interprets it would gravely
and without adequate justification injure interests of the
kind the First Amendment protects. Thus, there is “a
                  Cite as: 561 U. S. ____ (2010)           17

                     BREYER, J., dissenting

serious doubt” as to the statute’s constitutionality. Cro
well, 285 U. S., at 62. And where that is so, we must
“ascertain whether a construction of the statute is fairly
possible by which the question may be avoided.” Ibid.; see
also Ashwander, 297 U. S., at 346–348 (Brandeis, J.,
concurring); Zadvydas v. Davis, 533 U. S. 678, 689 (2001);
United States v. X-Citement Video, Inc., 513 U. S. 64, 78
(1994); United States v. Jin Fuey Moy, 241 U. S. 394, 401
(1916).
  I believe that a construction that would avoid the consti
tutional problem is “fairly possible.” In particular, I would
read the statute as criminalizing First-Amendment
protected pure speech and association only when the
defendant knows or intends that those activities will assist
the organization’s unlawful terrorist actions. Under this
reading, the Government would have to show, at a mini
mum, that such defendants provided support that they
knew was significantly likely to help the organization
pursue its unlawful terrorist aims.
  A person acts with the requisite knowledge if he is
aware of (or willfully blinds himself to) a significant likeli
hood that his or her conduct will materially support the
organization’s terrorist ends. See Allen v. United States,
164 U. S. 492, 496 (1896); cf. ALI, Model Penal Code
§2.02(2)(b)(ii) (1962). See also United States v. Santos, 553
U. S. 507, 521 (2008) (plurality opinion); cf. Model Penal
Code §2.02(7) (willful blindness); S. Rep. No. 95–605, pt. 1,
pp. 59–60 (1977). A person also acts with the requisite
intent if it is his “conscious objective” (or purpose) to fur
ther those same terrorist ends. See United States v. Bai
ley, 444 U. S. 394, 408 (1980); Model Penal Code
§§2.02(2)(a) and 2.02(5) (“When acting knowingly suffices
to establish an element, such element also is established if
a person acts purposely”). On the other hand, for the
reasons I have set out, see supra, at 9–12, knowledge or
intent that this assistance (aimed at lawful activities)
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                     BREYER, J., dissenting

could or would help further terrorism simply by helping to
legitimate the organization is not sufficient.
   This reading of the statute protects those who engage in
pure speech and association ordinarily protected by the
First Amendment. But it does not protect that activity
where a defendant purposefully intends it to help terror
ism or where a defendant knows (or willfully blinds him
self to the fact) that the activity is significantly likely to
assist terrorism. Where the activity fits into these catego
ries of purposefully or knowingly supporting terrorist
ends, the act of providing material support to a known
terrorist organization bears a close enough relation to
terrorist acts that, in my view, it likely can be prohibited
notwithstanding any First Amendment interest.              Cf.
Brandenburg, 395 U. S. 444. At the same time, this read
ing does not require the Government to undertake the
difficult task of proving which, as between peaceful and
nonpeaceful purposes, a defendant specifically preferred;
knowledge is enough. See Bailey, supra, at 405 (defining
specific intent).
   This reading is consistent with the statute’s text. The
statute prohibits “knowingly provid[ing] material support
or resources to a foreign terrorist organization.”
§2339B(a)(1) (emphasis added). Normally we read a crimi
nal statute as applying a mens rea requirement to all of
the subsequently listed elements of the crime. See Flores-
Figueroa v. United States, 556 U. S. ___, ___ (2009) (slip
op., at 6–7). So read, the defendant would have to know or
intend (1) that he is providing support or resources, (2)
that he is providing that support to a foreign terrorist
organization, and (3) that he is providing support that is
material, meaning (4) that his support bears a significant
likelihood of furthering the organization’s terrorist ends.
   This fourth requirement flows directly from the statute’s
use of the word “material.” That word can mean being of a
physical or worldly nature, but it also can mean “being of
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                     BREYER, J., dissenting

real importance or great consequence.” Webster’s Third
New International Dictionary 1392 (1961). Here, it must
mean the latter, for otherwise the statute, applying only to
physical aid, would not apply to speech at all. See also
§2339A(b)(1) (defining “ ‘material support or resources’ ” as
“any property, tangible or intangible” (emphasis added)).
And if the statute applies only to support that would likely
be of real importance or great consequence, it must have
importance or consequence in respect to the organization’s
terrorist activities. That is because support that is not
significantly likely to help terrorist activities, for purposes
of this statute, neither has “importance” nor is of “great
consequence.”
   The statutory definition of “material support” poses no
problem. The statute defines “material support” through
reference to a list of terms, including those at issue here—
“training,” “expert advice or assistance,” “personnel,” and
“service.” §2339B(g)(4); §2339A(b)(1). Since these latter
terms all fall under the definition of the term “material
support,” these activities fall within the statute’s scope
only when they too are “material.” Cf. Stevens, 559 U. S.,
at ___ (slip op., at 12) (citing Leocal v. Ashcroft, 543 U. S.
1, 11 (2004) (definitional phrase may take meaning from
the term to be defined)).
   Thus, textually speaking, a statutory requirement that
the defendant knew the support was material can be read
to require the Government to show that the defendant
knew that the consequences of his acts had a significant
likelihood of furthering the organization’s terrorist, not
just its lawful, aims.
   I need not decide whether this is the only possible read
ing of the statute in cases where “material support” takes
the form of “currency,” “property,” “monetary instru
ments,” “financial securities,” “financial services,” “lodg
ing,” “safehouses,” “false documentation or identification,”
“weapons,” “lethal substances,” or “explosives,” and the
20        HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

like. §2339A(b)(1). Those kinds of aid are inherently more
likely to help an organization’s terrorist activities, either
directly or because they are fungible in nature. Thus, to
show that an individual has provided support of those
kinds will normally prove sufficient for conviction (assum
ing the statute’s other requirements are met). But where
support consists of pure speech or association, I would
indulge in no such presumption. Rather, the Government
would have to prove that the defendant knew he was
providing support significantly likely to help the organiza
tion pursue its unlawful terrorist aims (or, alternatively,
that the defendant intended the support to be so used).
   The statute’s history strongly supports this reading.
That history makes clear that Congress primarily sought
to end assistance that takes the form of fungible donations
of money or goods. See, e.g., H. R. Rep. No. 104–383, at
38, 43–45, 81; supra, at 8–9. It shows that Congress,
when referring to “expert services and assistance” for
example, had in mind training that was sufficiently fungi
ble to further terrorism directly, such as an aviation ex
pert’s giving “advice” that “facilitat[es] an aircraft hijack
ing” or an accountant’s giving “advice” that will “facilitate
the concealment of funds used to support terrorist activi
ties.” Hearing on Administration’s Draft Anti-Terrorism
Act of 2001 before the House Committee on the Judiciary,
107th Cong., 1st Sess., 61 (2001).
   And the Chairman of the Senate Committee on the
Judiciary, when reporting the relevant bill from Commit
tee, told the Senate:
     “This bill also includes provisions making it a crime to
     knowingly provide material support to the terrorist
     functions of foreign groups designated by a Presiden
     tial finding to be engaged in terrorist activities.” 142
     Cong. Rec. S3354 (1996) (statement of Sen. Hatch)
     (emphasis added).
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                     BREYER, J., dissenting

He then added:
    “I am convinced we have crafted a narrow but effec
    tive designation provision which meets these obliga
    tions while safeguarding the freedom to associate,
    which none of us would willingly give up.” Id., at
    S3360.
Consistent with this view, the statute itself says:
    “Nothing in this section shall be construed or applied
    so as to abridge the exercise of rights guaranteed un
    der the First Amendment to the Constitution of the
    United States.” §2339B(i).
   In any event, the principle of constitutional avoidance
demands this interpretation. As Part II makes clear,
there is a “serious” doubt—indeed, a “grave” doubt—about
the constitutionality of the statute insofar as it is read to
criminalize the activities before us. Crowell, 285 U. S., at
62; see also Ashwander, 297 U. S., at 346–348 (Brandeis,
J., concurring); Jin Fuey Moy, 241 U. S., at 401. We there
fore must “read the statute to eliminate” that constitu
tional “doub[t] so long as such a reading is not plainly
contrary to the intent of Congress.” X-Citement Video,
Inc., 513 U. S., at 78.
   For this reason, the majority’s statutory claim that
Congress did not use the word “knowingly” as I would use
it, ante, at 12–13, and n. 3, is beside the point. Our conse
quent reading is consistent with the statute’s text; it is
consistent with Congress’ basic intent; it interprets but
does not significantly add to what the statute otherwise
contains. Cf. e.g., United States v. Thirty-seven Photo
graphs, 402 U. S. 363, 373–374 (1971) (constitutionally
compelled to add requirement that “forfeiture proceedings
be commenced within 14 days and completed within 60
days” despite absence of any statutory time limits); NLRB
v. Catholic Bishop of Chicago, 440 U. S. 490, 507 (1979)
22        HOLDER v. HUMANITARIAN LAW PROJECT

                     BREYER, J., dissenting

(constitutionally compelled to interpret “employer” as
implicitly excluding “church-operated schools” despite
silence and eight other different but explicit exceptions).
We should adopt it.
                              III
   Having interpreted the statute to impose the mens rea
requirement just described, I would remand the cases so
that the lower courts could consider more specifically the
precise activities in which the plaintiffs still wish to en
gage and determine whether and to what extent a grant of
declaratory and injunctive relief were warranted. I do not
see why the majority does not also remand the cases for
consideration of the plaintiffs’ activities relating to “advo
cating” for the organizations’ peaceful causes. See ante, at
19–20, 32–33.
   The majority does not remand, apparently because it
believes the plaintiffs lose automatically in that these
“advocacy” claims are too general. It adds that the plain
tiffs did not “suggest what exactly their ‘advocacy’ would
consist of.” Ante, at 33. But the majority is wrong about
the lack of specificity. The record contains complaints and
affidavits, which describe in detail the forms of advocacy
these groups have previously engaged in and in which
they would like to continue to engage. See App. 56–63,
78–87, 95–99, 110–123.
   Moreover, the majority properly rejects the Govern
ment’s argument that the plaintiffs’ speech-related activi
ties amount to “conduct” and should be reviewed as such.
Government Brief 44–57. Hence, I should think the ma
jority would wish the lower courts to reconsider this aspect
of the cases, applying a proper standard of review. See,
e.g., Philip Morris USA v. Williams, 549 U. S. 346, 357–
358 (2007); Johnson v. California 543 U. S. 499, 515
(2005); cf. Ricci v. DeStefano, 557 U. S. ___, ___ (2009) (slip
op., at 25) (GINSBURG, J., dissenting) (“When this Court
                 Cite as: 561 U. S. ____ (2010)          23

                    BREYER, J., dissenting

formulates a new legal rule, the ordinary course is to
remand and allow the lower courts to apply the rule in the
first instance”).
                              IV
   In sum, these cases require us to consider how to apply
the First Amendment where national security interests
are at stake. When deciding such cases, courts are aware
and must respect the fact that the Constitution entrusts to
the Executive and Legislative Branches the power to
provide for the national defense, and that it grants par
ticular authority to the President in matters of foreign
affairs. Nonetheless, this Court has also made clear that
authority and expertise in these matters do not automati
cally trump the Court’s own obligation to secure the pro
tection that the Constitution grants to individuals. Cf.
Hamdi v. Rumsfeld, 542 U. S. 507, 536 (2004) (“We have
long since made clear that a state of war is not a blank
check . . . when it comes to the rights of th[is] Nation’s
citizens”). In these cases, for the reasons I have stated, I
believe the Court has failed to examine the Government’s
justifications with sufficient care. It has failed to insist
upon specific evidence, rather than general assertion. It
has failed to require tailoring of means to fit compelling
ends. And ultimately it deprives the individuals before us
of the protection that the First Amendment demands.
   That is why, with respect, I dissent.
