                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 04-30249
                Plaintiff-Appellee,
               v.                            D.C. No.
                                           CR-03-00406-L
MICHAEL LEWIS CLARK,
                                             OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
         for the Western District of Washington
        Robert S. Lasnik, District Judge, Presiding

                  Argued and Submitted
            June 6, 2005—Seattle, Washington

                  Filed January 25, 2006

     Before: Procter Hug, Jr., Warren J. Ferguson, and
         M. Margaret McKeown, Circuit Judges.

               Opinion by Judge McKeown;
                Dissent by Judge Ferguson




                            999
1002                UNITED STATES v. CLARK


                          COUNSEL

Michael Filipovic, Assistant Federal Public Defender, Seattle,
Washington, for the defendant-appellant.

John McKay, United States Attorney, Seattle, Washington;
Helen J. Brunner, Assistant United States Attorney, Seattle,
Washington; John J. Lulejian, Assistant United States Attor-
ney, Seattle, Washington; Susan B. Dohrmann, Assistant
United States Attorney, Seattle, Washington, for the plaintiff-
appellee.


                          OPINION

McKEOWN, Circuit Judge:

  In this appeal we are confronted with a question of first
impression regarding the scope of Congress’s power under the
Foreign Commerce Clause.1 At issue is whether Congress




  1
    We commend both counsel for their excellent and comprehensive
briefing on this novel issue.
                     UNITED STATES v. CLARK                    1003
exceeded its authority “to regulate Commerce with foreign
Nations,” U.S. Const. art. I, § 8, cl. 3, in enacting a statute that
makes it a felony for any U.S. citizen who travels in “foreign
commerce,” i.e. to a foreign country, to then engage in an ille-
gal commercial sex act with a minor. 18 U.S.C. § 2423(c). We
hold that Congress acted within the bounds of its constitu-
tional authority.

   Congressional invocation of the Foreign Commerce Clause
comes as no surprise in light of growing concern about U.S.
citizens traveling abroad who engage in sex acts with chil-
dren. The United States reiterated its commitment to quelling
sexual abuse abroad by signing The Yokohama Global Com-
mitment 2001, available at http://www.unicef.org/events/
yokohama/outcome.html (last visited Dec. 29, 2005), which
was concluded at the Second World Congress Against the
Commercial Sexual Exploitation of Children. The Commit-
ment welcomes “new laws to criminalize [child prostitution],
including provisions with extra-territorial effect.” Id. Notably,
in an explanatory statement attached to the Commitment, the
United States emphasized that it “believes that the Optional
Protocol [on child prostitution] and [the International Labour
Organization’s Convention No. 182 regarding child labor]
provide a clear starting point for international action concern-
ing the elimination of commercial sexual exploitation of chil-
dren.” Id.

   Under the Commerce Clause, Congress has power “[t]o
regulate Commerce with foreign Nations, and among the sev-
eral States, and with the Indian Tribes.” This seemingly sim-
ple grant of authority has been the source of much dispute,
although very little of the controversy surrounds the “foreign
Nations” prong of the clause. Cases involving the reach of the
Foreign Commerce Clause vis-a-vis congressional authority
to regulate our citizens’ conduct abroad are few and far
between. See, e.g., United States v. Bredimus, 352 F.3d 200,
207-08 (5th Cir. 2003) (affirming conviction under 18 U.S.C.
§ 2423(b), which reaches any person who travels in foreign
1004                  UNITED STATES v. CLARK
commerce “for the purpose of” engaging in illicit sexual con-
duct).2 It is not so much that the contours of the Foreign Com-
merce Clause are crystal clear, but rather that their scope has
yet to be subjected to judicial scrutiny.

   The Supreme Court has long adhered to a framework for
domestic commerce comprised of “three general categories of
regulation in which Congress is authorized to engage under its
commerce power,” Gonzales v. Raich, 125 S. Ct. 2195, 2205
(2005): (1) the use of the channels of interstate commerce; (2)
the instrumentalities of interstate commerce, or persons or
things in interstate commerce; and (3) activities that substan-
tially affect interstate commerce. See also United States v.
Lopez, 514 U.S. 549, 558-59 (1995); Raich, 125 S. Ct. at 2215
(Scalia, J., concurring) (noting that for over thirty years, “our
cases have mechanically recited that the Commerce Clause
permits congressional regulation of three categories”). This
framework developed in response to the unique federalism
concerns that define congressional authority in the interstate
context. Lopez, 514 U.S. at 557 (“[T]he scope of the interstate
commerce power ‘must be considered in the light of our dual
system of government . . . .’ ”) (quoting NLRB v. Jones &
Laughlin Steel Corp., 301 U.S. 1, 37 (1937)). No analogous
framework exists for foreign commerce.

   Further distinguishing the two spheres “is evidence that the
Founders intended the scope of the foreign commerce power
to be . . . greater” as compared with interstate commerce.
Japan Line, Ltd. v. County of Los Angeles, 441 U.S. 434, 448
(1979). This expansive latitude given to Congress over for-
eign commerce is sensible given that “Congress’ power to
regulate interstate commerce may be restricted by consider-
ations of federalism and state sovereignty,” whereas “[i]t has
  2
   As discussed in § IV(A), the cases arise primarily under the dormant
Foreign Commerce Clause and invoke the interplay between state and fed-
eral authority.
                   UNITED STATES v. CLARK                 1005
never been suggested that Congress’ power to regulate foreign
commerce could be so limited.” Id. at 448 n.13.

   Adapting the interstate commerce categories to foreign
commerce in specific contexts is not an insurmountable task.
See, e.g., United States v. Cummings, 281 F.3d 1046, 1049 n.1
(9th Cir. 2002) (analyzing constitutionality of the Interna-
tional Parental Kidnaping Act, 18 U.S.C. § 1204(a), under
Lopez’s three-category approach). At times, however, this
undertaking can feel like jamming a square peg into a round
hole. Instead of slavishly marching down the path of grafting
the interstate commerce framework onto foreign commerce,
we step back and take a global, commonsense approach to the
circumstance presented here: The illicit sexual conduct
reached by the statute expressly includes commercial sex acts
performed by a U.S. citizen on foreign soil. This conduct
might be immoral and criminal, but it is also commercial.
Where, as in this appeal, the defendant travels in foreign com-
merce to a foreign country and offers to pay a child to engage
in sex acts, his conduct falls under the broad umbrella of for-
eign commerce and consequently within congressional
authority under the Foreign Commerce Clause.

                        BACKGROUND

   Michael Lewis Clark, a seventy-one year old U.S. citizen
and military veteran, primarily resided in Cambodia from
1998 until his extradition in 2003. He typically took annual
trips back to the United States and he also maintained real
estate, bank accounts, investment accounts, a driver’s license,
and a mailing address in this country. Following a family visit
in May 2003, Clark left Seattle and flew to Cambodia via
Japan, Thailand, and Malaysia. He was traveling on a busi-
ness visa that he renewed on an annual basis.

  While in Cambodia, Clark came to the attention of Action
Pour Les Enfants, a non-governmental organization whose
mission is to rescue minor boys who have been sexually
1006                   UNITED STATES v. CLARK
molested by non-Cambodians. Clark came under suspicion
when street kids reported to social workers that he was
molesting young boys on a regular basis. The organization in
turn reported him to the Cambodian National Police. In late
June 2003, the Cambodian police arrested Clark after discov-
ering him in a Phnom Penh guesthouse engaging in sex acts
with two boys who were approximately ten and thirteen years
old. He was charged with debauchery. The United States gov-
ernment received permission from the Cambodian govern-
ment to take jurisdiction over Clark.

   U.S. officials—assisted by the Cambodian National Police
and the Australian Federal Police—conducted an investiga-
tion that led to Clark’s confession and extradition to the
United States. As part of the investigation, the younger boy
told authorities that he had engaged in sex acts with Clark
because he needed money to buy food for his brother and sis-
ter. The older boy stated that Clark had hired him in the past
to perform sex acts, on one occasion paying five dollars.
Other young boys whom Clark had molested reported that
they were paid about two dollars, and Clark stated that he rou-
tinely paid this amount. Clark acknowledged that he had been
a pedophile since at least 1996, “maybe longer,” and had been
involved in sexual activity with approximately 40-50 children
since he began traveling in 1996.

  Upon his return to the United States, Clark was indicted
under the provisions of the newly-enacted Prosecutorial Rem-
edies and Other Tools to End the Exploitation of Children
Today Act of 2003 (“PROTECT Act”), Pub. L. No. 108-21,
117 Stat. 650 (2003).3 He pled guilty to two counts under 18
  3
    Although Clark was reportedly the first person charged under the PRO-
TECT Act’s extraterritorial provisions, see Blaine Harden, Veteran
Indicted on Sex Charges; Man Is First Charged Under Protect Law’s Pro-
vision on Tourism, Wash. Post at A5 (Sept. 25, 2003), the U.S. Immigra-
tion and Customs Enforcement’s “Operation Predator” reports that thirteen
arrests had been made as of July 19, 2005, http://www.ice.gov/graphics/
news/factsheets/statistics.htm (last visited Dec. 29, 2005).
                      UNITED STATES v. CLARK                    1007
U.S.C. § 2423(c) and (e)4 but reserved the right to appeal his
pre-trial motion to dismiss based on constitutional, jurisdic-
tional, and statutory construction grounds. See United States
v. Clark, 315 F. Supp. 2d 1127 (W.D. Wash. 2004) (order
denying Clark’s motion to dismiss).

   On appeal, Clark’s challenge centers on the constitutional-
ity of § 2423(c). Adopted in 2003 as part of the PROTECT
Act, § 2423(c) provides as follows:

      (c) Engaging in illicit sexual conduct in foreign
      places. Any United States citizen or alien admitted
      for permanent residence who travels in foreign com-
      merce, and engages in any illicit sexual conduct with
      another person shall be fined under this title or
      imprisoned not more than 30 years, or both.

   This provision was first proposed as part of the Sex Tour-
ism Prohibition Improvement Act of 2002, H.R. Rep. No.
107-525 (2002). The “Constitutional Authority Statement” in
the Report accompanying this Act expressly identified the
Commerce Clause, article I, section 8 of the Constitution, as
the authority for the legislation. Id. at 5. The purpose of the
bill was “to make it a crime for a U.S. citizen to travel to
another country and engage in illicit sexual conduct with
minors.” Id. The provision was not enacted, however, until it
was added to the PROTECT Act the following year. See H.R.
Rep. No. 108-66, at 5 (2003) (Conf. Rep.), as reprinted in
2003 U.S.C.C.A.N. 683. This section was incorporated verba-
tim into the 2003 legislation but the Report on the PROTECT
Act does not include the prior reference to constitutional
authority.

  Before the PROTECT Act became law in 2003, § 2423(b)
  4
    Subsection (e) provides that an attempt or conspiracy to violate
§ 2423(c) shall be punishable in the same manner as a completed viola-
tion.
1008                    UNITED STATES v. CLARK
required the government to prove that the defendant “travel-
[ed] in foreign commerce, or conspire[d] to do so, for the pur-
pose of engaging in” specified sexual conduct with a person
under eighteen years of age. Violent Crime Control and Law
Enforcement Act of 1994, Pub. L. 103-322, 108 Stat. 1796,
Sec. 160001 (1994) (codified as amended at 18 U.S.C.
§ 2423(b)) (emphasis added). The PROTECT Act replaced
this single section with new subsections (b) through (g), with
the new subsection (b) remaining substantively the same as
the former subsection (b). Subsection (c) is an entirely new
section which deletes the “for the purpose of” language.5 The
conference report accompanying the PROTECT Act explains
that Congress removed the intent requirement from § 2423(c)
so that “the government would only have to prove that the
defendant engaged in illicit sexual conduct with a minor while
in a foreign country.” H.R. Rep. No. 108-66 at 51; see also
H.R. Rep. No. 107-525, at 2 (same statement in report for
failed 2002 bill). Consequently, for § 2423(c) to apply, the
two key determinations are whether the defendant “travel[ed]
in foreign commerce” and “engages in any illicit sexual con-
duct.”

   The statute defines “illicit sexual conduct” in two ways:
First, the definition includes “a sexual act (as defined in sec-
tion 2246 [18 U.S.C. § 2246]) with a person under 18 years
of age that would be in violation of chapter 109A [18 U.S.C.
§§ 2241 et seq.] if the sexual act occurred in the special mari-
time and territorial jurisdiction of the United States.” 18
U.S.C. § 2423(f)(1). Chapter 109A, in turn, criminalizes vari-
ous forms of sexual abuse including, for example, aggravated
sexual abuse by force, threat, or other means, 18 U.S.C.
  5
    Subsection (d) covers persons who provide ancillary services to facili-
tate travel “for the purpose of” engaging in illegal acts; subsection (e) cov-
ers attempt and conspiracy; subsection (f) cross-references the definition
of “illegal sexual conduct” with other statutes; and subsection (g) provides
a defense where the defendant in a commercial sex act case reasonably
believed that the person was 18 years old. 18 U.S.C. § 2423(d)-(g).
                        UNITED STATES v. CLARK                        1009
§ 2241(a)-(b); sexual abuse by threatening or placing that
other person in fear, 18 U.S.C. § 2242; and sexual abuse of a
minor or ward, 18 U.S.C. § 2243. These violations share the
common characteristic that there is no economic component
to the crime. In other words, they are non-commercial sex
acts.

    In contrast, the second prong of the definition covers “any
commercial sex act (as defined in section 1591 [18 U.S.C.
§ 1591]) with a person under 18 years of age.” 18 U.S.C.
§ 2423(f)(2). “Commercial sex act,” in turn, is defined as
“any sex act, on account of which anything of value is given
to or received by any person.” 18 U.S.C. § 1591(c)(1). Clark
acknowledges that his conduct qualifies as illicit sexual con-
duct, and he admitted in his plea agreement that he “intended
to pay each of the boys and each of the boys expected such
payment in exchange for the sexual encounter.” Accordingly,
it is this second “commercial sex act” prong that is at issue in
Clark’s appeal.

                                ANALYSIS

   Clark does not dispute that he traveled in “foreign com-
merce,” nor does he dispute that he engaged in illicit commer-
cial sexual conduct. The challenge he raises is to
congressional authority to regulate this conduct. In addition to
his Commerce Clause challenge, Clark attacks his conviction
on international law, statutory construction, and Due Process
grounds.6 In recognition of the principle that courts have a
“strong duty to avoid constitutional issues that need not be
resolved in order to determine the rights of the parties to the
case under consideration,” County Court of Ulster County v.
Allen, 442 U.S. 140, 154 (1979), we begin our analysis with
Clark’s non-constitutional claims.
  6
   Clark initially raised issues related to his sentence but has since with-
drawn this aspect of his appeal.
1010                    UNITED STATES v. CLARK
I.       SECTION 2423(C) COMPORTS           WITH THE       PRINCIPLES     OF
         INTERNATIONAL LAW

   We start with Clark’s argument that extraterritorial applica-
tion of § 2423(c) violates principles of international law.7 On
de novo review, United States v. Felix-Gutierrez, 940 F.2d
1200, 1203-04 (9th Cir. 1991), we hold that extraterritorial
application is proper based on the nationality principle.

   [1] The legal presumption that Congress ordinarily intends
federal statutes to have only domestic application, see Small
v. United States, 125 S. Ct. 1752, 1755 (2005), is easily over-
come in Clark’s case because the text of § 2423(c) is explicit
as to its application outside the United States. See 18 U.S.C.
§ 2423(c) (titled “Engaging in illicit sexual conduct in foreign
places” and reaching people “who travel[ ] in foreign com-
merce”); see also Sale v. Haitian Ctrs. Council, Inc., 509 U.S.
155, 176 (1993) (explaining that there must be “affirmative
evidence of intended extraterritorial application”). By its
terms, the provision is exclusively targeted at extraterritorial
conduct.

   [2] Having addressed this threshold issue, we ask whether
the exercise of extraterritorial jurisdiction in this case com-
ports with principles of international law. See United States v.
     7
    Clark’s challenge is distinct from the more common scenario where a
party challenges only the extraterritorial reach of a statute without contest-
ing congressional authority to enact the statute. See, e.g., Small v. United
States, 125 S. Ct. 1752, 1754 (2005) (holding that the phrase “convicted
in any court” in a statute criminalizing firearm possession by a convicted
felon, 18 U.S.C. § 922(g)(1), does not apply to extraterritorial convic-
tions); Timberlane Lumber Co. v. Bank of Am., 549 F.2d 597, 608-15 (9th
Cir. 1976) (discussing the extraterritorial reach of U.S. antitrust laws to
activities in foreign countries), superseded by statute as stated in
McGlinchy v. Shell Chemical Co., 845 F.2d 802, 813 n.8 (9th Cir. 1988);
United States v. Cotten, 471 F.2d 744, 750 (9th Cir. 1973) (holding that
a statute proscribing theft of government property applied extraterritori-
ally, and that the “law certainly represents an exercise by the Government
of its right to defend itself from obstructions and frauds”).
                         UNITED STATES v. CLARK                            1011
Vasquez-Velasco, 15 F.3d 833, 839 (9th Cir. 1994) (“In deter-
mining whether a statute applies extraterritorially, we also
presume that Congress does not intend to violate principles of
international law.”) (citing McCulloch v. Sociedad Nacional
de Marineros de Honduras, 372 U.S. 10, 21-22 (1963)); see
also United States v. Neil, 312 F.3d 419, 421 (9th Cir. 2002).
Of the five general principles that permit extraterritorial crim-
inal jurisdiction,8 the nationality principle most clearly applies
to Clark’s case. The nationality principle “permits a country
to apply its statutes to extraterritorial acts of its own nation-
als.” United States v. Hill, 279 F.3d 731, 740 (9th Cir. 2002).
Jurisdiction based solely on the defendant’s status as a U.S.
citizen is firmly established by our precedent. See, e.g.,
United States v. Walczak, 783 F.2d 852, 854 (9th Cir. 1986)
(holding that jurisdiction over a U.S. citizen who violated a
federal statute while in Canada was proper under the national-
ity principle); McKeel v. Islamic Repub. of Iran, 722 F.2d
582, 588 (9th Cir. 1983) (noting that nationality principle per-
mits states to punish the wrongful conduct of its citizens);
United States v. King, 552 F.2d 833, 851 (9th Cir. 1976)
(commenting that nationality principle would apply to U.S.
citizen defendants). Clark’s U.S. citizenship is uncontested.9
Accordingly, extraterritorial application of § 2423(c) to
Clark’s conduct is proper based on the nationality principle.10
  8
     The five jurisdictional bases are territorial, national, protective, univer-
sal, and passive personality. See Restatement (Third) of Foreign Relations
Law of the United States § 402 (1987); United States v. Hill, 279 F.3d
731, 739 (9th Cir. 2002) (listing the five principles).
   9
     Because Clark is a U.S. citizen, we do not reach the issue whether reli-
ance on the nationality principle is also proper when “alien[s] admitted for
permanent residence” are prosecuted under § 2423(c). 18 U.S.C.
§ 2423(c).
   10
      Although the district court found that extraterritorial jurisdiction was
proper under both the nationality principle and universality principle,
Clark, 315 F. Supp. 2d at 1131, we decline to address whether the univer-
sality principle also applies in Clark’s case because extraterritorial appli-
cation of a criminal law need be justified by only one of the five principles
of extraterritorial authority. See Chua Han Mow v. United States, 730 F.2d
1308, 1312 (9th Cir. 1984).
1012                 UNITED STATES v. CLARK
   Clark also seeks to invalidate the statute because, in his
view, extraterritorial application is unreasonable. See Restate-
ment (Third) of Foreign Relations Law of the United States
§ 403 (1987); Vasquez-Velasco, 15 F.3d at 840-41 (holding
that extraterritorial application of U.S. statute to violent
crimes associated with drug trafficking was reasonable under
international law). The record provides no support for this
argument. Clark cites no precedent in which extraterritorial
application was found unreasonable in a similar situation.
Cambodia consented to the United States taking jurisdiction
and nothing suggests that Cambodia objected in any way to
Clark’s extradition and trial under U.S. law. Clark himself
stated to a U.S. official in Cambodia that he “wanted to return
to the United States” because he saw people dying in the
Cambodian prison “and was very much afraid that if [he]
stayed in that prison, [he] would not survive.” Having been
saved from immediate prosecution in Cambodia, it is some-
what ironic that he now challenges the law in a United States
court.

II.    CLARK’S CONDUCT FALLS WITHIN              THE   SCOPE    OF
       § 2423(C)

   Clark posits that § 2423(c) can be saved from constitutional
scrutiny by interpreting it to require that the illicit sexual con-
duct take place while the defendant is literally still traveling.
The district court declined to dismiss the indictment on this
ground, explaining that “Clark is attempting to add elements
to the crime . . . that simply do not exist in the statute.” Clark,
315 F. Supp. 2d at 1130. We agree. Despite Clark’s efforts to
distance himself from the statute, we are unable to resolve this
appeal by excising Clark’s conduct from the reach of
§ 2423(c). Cf. Jones v. United States, 529 U.S. 848, 850-51
(2000) (avoiding constitutional challenge by construing stat-
ute’s text to hold that certain owner-occupied residences do
not qualify as property “used in” commerce).
                      UNITED STATES v. CLARK                     1013
   The statute is plain on its face: Section 2423(c) reaches
“[a]ny United States citizen or alien admitted for permanent
residence who travels in foreign commerce, and engages in
any illicit sexual conduct with another person.” It does not
require that the conduct occur while traveling in foreign com-
merce. In Clark’s case, the lapse in time between his most
recent transit between the United States and Cambodia and
his arrest was less than two months. We see no plausible read-
ing of the statute that would exclude its application to Clark’s
conduct because of this limited gap.11 Because the statute is
unambiguous and Clark’s conduct falls squarely within the
class of persons whose conduct Congress intended to crimi-
nalize under this statute, we do not invoke the rule of lenity.
Jones, 529 U.S. at 858 (“ambiguity concerning the ambit of
criminal statutes should be resolved in favor of lenity”) (cita-
tion omitted).

   The legislative history also supports the plain reading that
we adopt. The conference report explains that Congress elimi-
nated the intent requirement so that “the government would
only have to prove that the defendant engaged in illicit sexual
conduct with a minor while in a foreign country.” H.R. Rep.
No. 108-66 at 51. From a practical perspective, it seems non-
sensical for Congress to limit the scope of § 2423(c) to the
unlikely scenario where the abuse occurs while the perpetrator
is literally en route. This reading would eviscerate § 2423(c)
by severely limiting its use to only those people who commit
the offense while physically onboard an international flight,
cruise, or other mode of transportation. We decline to adopt
Clark’s strained reading of the statute.

III.   NO DUE PROCESS VIOLATION

  The next question is whether extraterritorial application of
  11
    Whether a longer gap between the travel and the commercial sex act
could trigger constitutional or other concerns is an issue we leave for
another day.
1014                    UNITED STATES v. CLARK
§ 2423(c) violates the Due Process Clause of the Fifth
Amendment because there is an insufficient nexus between
Clark’s conduct and the United States. We hold that, based on
Clark’s U.S. citizenship, application of § 2423(c) to his extra-
territorial conduct is neither “arbitrary [n]or fundamentally
unfair.” United States v. Davis, 905 F.2d 245, 249 (9th Cir.
1990).12

   [3] Clark is correct that to comply with the Due Process
Clause of the Fifth Amendment, extraterritorial application of
federal criminal statutes requires the government to demon-
strate a sufficient nexus between the defendant and the United
States “so that such application would not be arbitrary or fun-
damentally unfair.” Davis, 905 F.2d at 248-49. Indeed, “even
resort to the Commerce Clause can[not] defy the standards of
due process.” Sec’y of Agric. v. Cent. Roig Refining Co., 338
U.S. 604, 616 (1950).

   [4] In Blackmer v. United States, 284 U.S. 421 (1932), the
Supreme Court explained that the extraterritorial application
of U.S. law to its citizens abroad did not violate the Fifth
Amendment. The Court declared that despite moving his resi-
dence to France, the U.S.-citizen defendant “continued to owe
allegiance to the United States. By virtue of the obligations of
citizenship, the United States retained its authority over him,
and he was bound by its laws made applicable to him in a for-
eign country.” Id. at 436. This longstanding principle that citi-
zenship alone is sufficient to satisfy Due Process concerns
still has force. Citing Blackmer, we recently affirmed that
“[t]here is no doubt that the United States may exercise juris-
diction over American nationals living abroad, regardless of
where the crime is committed.” United States v. Corey, 232
F.3d 1166, 1179 n.9 (9th Cir. 2000).
  12
     Although Clark’s citizenship alone is sufficient to satisfy Due Process
concerns, his U.S. investments, ongoing receipt of federal retirement bene-
fits and use of U.S. military flights also underscore his multiple and con-
tinuing ties with this country.
                        UNITED STATES v. CLARK                        1015
   Clark offers no authority that calls into question this princi-
ple. Instead, he relies on cases that involved foreign nationals,
which meant that the courts had no choice but to look beyond
nationality to establish the defendants’ ties with the United
States. See, e.g., United States v. Klimavicius-Viloria, 144
F.3d 1249, 1254 (9th Cir. 1998) (defendant and crew “were
all Columbians”); Davis, 905 F.2d at 247 (“Davis is not a citi-
zen of the United States.”).

   [5] Clark is a U.S. citizen, a bond that “implies a duty of
allegiance on the part of the member and a duty of protection
on the part of the society. These are reciprocal obligations,
one being a compensation for the other.” Luria v. United
States, 231 U.S. 9, 22 (1913). Predicated on this imputed alle-
giance, application of § 2423(c) to Clark’s extraterritorial
conduct does not violate the Due Process Clause.13 Having
concluded that none of Clark’s other arguments resolve this
appeal, we turn to Clark’s Commerce Clause challenge.

IV.    CONGRESS’S FOREIGN COMMERCE CLAUSE POWER
       EXTENDS TO REGULATING COMMERCIAL SEX ACTS
       ABROAD

   In considering whether Congress exceeded its power under
the Foreign Commerce Clause in enacting § 2423(c), we
  13
     Clark also raises notice and vagueness challenges, neither of which
withstands scrutiny. Section 2423(c) was enacted in April 2003—while
Clark was visiting the United States—and the commercial sex act did not
occur until June 2003. Mere “ignorance of the law will not excuse.”
Shevlin-Carpenter Co. v. Minn., 218 U.S. 57, 68 (1910). Clark might have
been ignorant of the law, but he had constitutionally sufficient notice. We
are not persuaded by Clark’s argument that the statute’s “travels in foreign
commerce” language gave him “no reasonable basis” to anticipate being
haled into a U.S. court. For a criminal statute to survive a vagueness chal-
lenge, we require only that “a reasonable person of ordinary intelligence
would understand what conduct the statute prohibits.” United States v.
Lee, 183 F.3d 1029, 1032 (9th Cir. 1999). A reasonable person would eas-
ily understand § 2423(c) to cover Clark’s travel to Cambodia and sexual
conduct with minors there.
1016                    UNITED STATES v. CLARK
ground our analysis in the fundamental principle that “[i]t is
an essential attribute of [Congress’s power over foreign com-
merce] that it is exclusive and plenary.” Bd. of Trustees of
Univ. of Ill. v. United States, 289 U.S. 48, 56 (1933). We are
further mindful of the Supreme Court’s caution that “[d]ue
respect for the decisions of a coordinate branch of Govern-
ment demands that we invalidate a congressional enactment
only upon a plain showing that Congress has exceeded its
constitutional bounds.” United States v. Morrison, 529 U.S.
598, 607 (2000). No plain showing has been made here. In
light of Congress’s sweeping powers over foreign commerce,
we conclude that Congress acted within its constitutional
bounds in criminalizing commercial sex acts committed by
U.S. citizens who travel abroad in foreign commerce.14
  14
     Our review of the constitutionality of § 2423(c) is focused on congres-
sional authority under the Commerce Clause. As pointed out by the Gov-
ernment, the Supreme Court once remarked in a case involving the
delegation of legislative power to the Executive that “[t]he broad state-
ment that the federal government can exercise no powers except those spe-
cifically enumerated in the Constitution, and such implied powers as are
necessary and proper to carry into effect the enumerated powers, is cate-
gorically true only in respect of our internal affairs.” United States v.
Curtiss-Wright Export Corp., 299 U.S. 304, 315-16 (1936). Standing
alone, however, this reference does not establish that the Foreign Com-
merce Clause has no meaning or is without bounds. Nor does it necessar-
ily mean that congressional regulation of external affairs has no limits.
The Government has not argued—nor is there any indication in the
legislation—that Congress enacted § 2423(c) based on an implied foreign
affairs power. Cf. United States v. Hernandez-Guerrero, 147 F.3d 1075,
1077 (9th Cir. 1998) (noting that in exercising immigration power, which
falls into the arena of foreign affairs, “Congress is not subject to the rigid
constraints that govern its authority in domestic contexts”). Nonetheless,
given our charge to uphold the statute absent a plain showing that it is
unconstitutional, United States v. Morrison, 529 U.S. 598, 607 (2000), we
acknowledge that Congress’s plenary authority over foreign affairs may
also provide a sufficient basis for § 2423(c). See, e.g., Curtiss-Wright
Export Corp., 299 U.S. at 315; United States v. Belmont, 301 U.S. 324,
331 (1937) (“[C]omplete power over international affairs is in the national
government . . .”).
                        UNITED STATES v. CLARK                        1017
   At the outset, we highlight that § 2423(c) contemplates two
types of “illicit sexual conduct”: non-commercial and com-
mercial. Clark’s conduct falls squarely under the second
prong of the definition, which criminalizes “any commercial
sex act . . . with a person under 18 years of age.” 18 U.S.C.
§ 2423(f)(2).15 In view of this factual posture, we abide by the
rule that courts have a “strong duty to avoid constitutional
issues that need not be resolved in order to determine the
rights of the parties to the case under consideration,” County
Court of Ulster County, 442 U.S. at 154, and limit our holding
to § 2423(c)’s regulation of commercial sex acts.16
  15
       That the authorities arrested Clark before the money had actually
changed hands is immaterial to our analysis. Clark does not dispute that
he hired the boys to engage in sex acts with the promise of monetary pay-
ment, and the statute does not require that the victims be paid by the
defendant prior to arrest. See 18 U.S.C. § 2423(e) (providing that an
attempt to violate § 2423(c) shall be punishable in the same manner as a
completed violation). In fact, the second count to which Clark pled guilty
was that he traveled in foreign commerce and “thereafter attempted to
engage in illicit sexual conduct.”
    16
       We do not decide the constitutionality of § 2423(c) with respect to
illicit sexual conduct covered by the non-commercial prong of the statute,
such as sex acts accomplished by use of force or threat. See 18 U.S.C.
§ 2423(f) (defining “illicit sexual conduct” in part by reference to crimes
listed under 18 U.S.C. §§ 2241 et seq.). The situation presented by
§ 2423(c) is distinct from challenges in which courts have carved out a
discrete subset of conduct from a statute based on distinctions deduced
from the statutory scheme. See, e.g., Raich, 125 S. Ct. at 2211 (disagreeing
with this court’s isolation of a “separate and distinct” class of activities
beyond the reach of the federal statute and instead concluding that the sub-
divided class “was an essential part of the larger regulatory scheme”);
United States v. McCoy, 323 F.3d 1114, 1115 (9th Cir. 2003) (holding a
statute unconstitutional as applied to the limited category of simple intra-
state possession of child pornography that had not traveled in interstate
commerce). Here, the statute is plain on its face in dividing the definition
of “illicit sexual conduct” into two distinct, numbered prongs. We address
only the prong that applies to Clark’s conduct. This decision to limit our
holding to commercial sex acts is an expression of judicial restraint, not
an attempt to atomize a cohesive statutory scheme.
1018                UNITED STATES v. CLARK
  A.   THE COMMERCE CLAUSE: STRUCTURE AND HISTORY

   Chief Justice Marshall observed long ago that “[t]he
objects, to which the power of regulating commerce might be
directed, are divided into three distinct classes—foreign
nations, the several states, and Indian Tribes. When forming
this article, the convention considered them as entirely dis-
tinct.” Cherokee Nation v. Georgia, 30 U.S. 1, 18 (1831).
Looking to the text, the single clause indeed embodies three
subclauses for which distinct prepositional language is used:
“To regulate Commerce with foreign Nations, and among the
several States, and with the Indian Tribes.” U.S. Const. art. I,
§ 8, cl. 3.

   Among legal scholars there has been considerable debate
over the intrasentence unity—or disunity, as the case may be
—of the three subclauses, considering that they share the
common language “[t]o regulate Commerce.” Some commen-
tators take the view that Congress’s powers over commerce
with foreign nations and Indian tribes are broader than over
interstate commerce. See, e.g., Kenneth M. Casebeer, The
Power to Regulate “Commerce with Foreign Nations” in a
Global Economy and the Future of American Democracy: An
Essay, 56 U. Miami L. Rev. 25, 33-41 (2001); 1 R. Rotunda
& J. Nowak, Treatise on Constitutional Law § 4.2 (3d ed.
1999) (“Even during periods when the Justices were debating
whether to significantly restrict the congressional power to
regulate intrastate activities under the commerce power, there
was no serious advocacy of restrictions on the federal powers
in these other areas.”).

  Other scholars maintain that Congress has coextensive
powers under the Commerce Clause’s subdivisions. See e.g.,
Louis Henkin, Foreign Affairs and the Constitution 70 n.9
(1972) (“It is generally accepted, however, that the power of
Congress is the same as regards both [foreign and interstate
commerce.”); Saikrishna Prakash, Our Three Commerce
Clauses and the Presumption of Intrasentence Uniformity, 55
                    UNITED STATES v. CLARK                   1019
Ark. L. Rev. 1149, 1173 (2003) (“In practice, we have three
different Commerce Clauses when text and history indicate
that we ought to have but one.”). Despite the long-running
lively debate among scholars, no definitive view emerges
regarding the relationship among the three subclauses. None-
theless, Supreme Court precedent points to the conclusion that
the Foreign Commerce Clause is different than the Interstate
Commerce Clause. See Japan Line, 441 U.S. at 448 (“[T]here
is evidence that the Founders intended the scope of the for-
eign commerce power to be . . . greater” as compared with
interstate commerce.).

   Regardless of how separate the three subclauses may be in
theory, the reality is that they have been subject to markedly
divergent treatment by the courts. This approach is not sur-
prising given the considerably different interests at stake
when Congress regulates in the various arenas. Most notably,
regardless of whether the subject matter is drugs, gender-
motivated violence, or gun possession, a prominent theme
runs throughout the interstate commerce cases: concern for
state sovereignty and federalism. On the other hand, “[t]he
principle of duality in our system of government does not
touch the authority of the Congress in the regulation of for-
eign commerce.” Bd. of Trustees of Univ. of Ill., 289 U.S. at
57. This distinction provides a crucial touchstone in applying
the Foreign Commerce Clause, for which Congress’s author-
ity to regulate has not been defined with the precision set
forth by Lopez and Morrison in the interstate context.

   We start with the component that has dominated judicial
consideration of the Commerce Clause: “among the several
States.” After decades of expansive reading by the courts, see,
e.g., Katzenbach v. McClung, 379 U.S. 294, 303-04 (1964)
(“[W]here we find that the legislators . . . have a rational basis
for finding a chosen regulatory scheme necessary to the pro-
tection of commerce, our investigation is at an end.”), the
mid-1990s saw a retrenchment in Commerce Clause jurispru-
dence beginning with the watershed case of Lopez. In Lopez,
1020                UNITED STATES v. CLARK
the Court held that a statute which criminalized possession of
a firearm in a school zone was beyond Congress’s Commerce
Clause authority. 514 U.S. at 552. In so holding, the Court
stressed its concern that an overly expansive view of the Inter-
state Commerce Clause “would effectually obliterate the dis-
tinction between what is national and what is local and create
a completely centralized government.” Id. at 557 (quoting
NLRB v. Jones & Laughlin Steel Corp., 301 U.S. at 37). The
Court reiterated these concerns five years later in Morrison in
striking down a provision under the Violence Against Women
Act: “[T]he concern . . . that Congress might use the Com-
merce Clause to completely obliterate the Constitution’s dis-
tinction between national and local authority seems well
founded.” Morrison, 529 U.S. at 615.

   In addition to announcing a shift to a more constrained
view of Congress’s power over interstate commerce, Lopez
and Morrison ossified the three-category framework that the
Court had long applied to interstate commerce cases. See
Lopez, 514 U.S. at 558-59; Morrison, 529 U.S. at 609-14; see
also Raich, 125 S. Ct. at 2215 (Scalia, J., concurring) (noting
that for over thirty years, “our cases have mechanically
recited that the Commerce Clause permits congressional regu-
lation of three categories”). As noted earlier, these three
familiar categories are (1) the use of the channels of interstate
commerce; (2) the instrumentalities of interstate commerce, or
persons or things in interstate commerce; and (3) activities
that substantially affect interstate commerce. See Lopez, 514
U.S. at 558-59. Within the interstate commerce arena, the
guiding force of Lopez and Morrison quickly took firm hold,
and lower courts have adhered closely to the three-prong
structure. See, e.g., United States v. Adams, 343 F.3d 1024,
1027-28 (9th Cir. 2003) (reciting the three categories set out
in Lopez and Morrison and applying the third to a statute
criminalizing the intrastate possession of child pornography).

   This past term the Court introduced a new wrinkle in inter-
state commerce’s jurisprudential fabric when it held that the
                     UNITED STATES v. CLARK                   1021
Controlled Substances Act was a valid exercise of Congress’s
powers under the Commerce Clause. See Raich, 125 S. Ct. at
2201. Raich did not alter the fundamental three-prong rubric,
but the Court took a more generous view of Congress’s power
over interstate commerce than seen in Lopez and Morrison.
Over the dissent’s pointed objections, the majority concluded
that “Congress had a rational basis for concluding that leaving
home-consumed marijuana outside federal control would sim-
ilarly affect price and market conditions.” Id. at 2207. This
“rational basis” for finding a nexus between home-consumed
marijuana and the interstate market put the regulation
“squarely within Congress’ commerce power.” Id. In tension
with the majority’s broad reading of Congress’s power over
interstate commerce, the dissent emphasized that setting
“outer limits” to Congress’s Commerce Clause powers “pro-
tect[s] historic spheres of state sovereignty from excessive
federal encroachment.” Id. at 2220 (O’Connor, J., dissenting).

   Although the Supreme Court’s view of the Interstate Com-
merce Clause has “evolved over time,” id. at 2205, Indian
Commerce Clause jurisprudence has been more of a straight
line proposition. See, e.g., United States v. Lara, 541 U.S.
193, 200 (2004) (“[T]he Constitution grants Congress broad
general powers to legislate in respect to Indian tribes, powers
that we have consistently described as ‘plenary and exclusive’
. . . This Court has traditionally identified the Indian Com-
merce Clause, U.S. Const., Art. I, § 8, cl. 3, and the Treaty
Clause, Art. II, § 2, cl. 2, as sources of that power.”) (citations
omitted). Indeed, the Supreme Court has commented on the
“very different applications” of the Interstate and Indian Com-
merce Clause powers, explaining that interstate commerce
jurisprudence “is premised on a structural understanding of
the unique role of the States in our constitutional system that
is not readily imported to cases involving the Indian Com-
merce Clause.” Cotton Petroleum Corp. v. New Mexico, 490
U.S. 163, 192 (1989). In contrast to the federal government’s
relationship with the states, its relationship with Indian tribes
is “based on a history of treaties and the assumption of a
1022               UNITED STATES v. CLARK
‘guardian-ward’ status.” Morton v. Mancari, 417 U.S. 535,
551 (1974). The Commerce Clause stands as one of the main
textual grants of Congress’s plenary power to regulate this
special relationship between the federal government and
Indian tribes. Id. at 551-52. In this context, the Court has
defined Congress’s authority under the Indian Commerce
Clause without reference to the rigid categories of Lopez and
Morrison. See, e.g., Lara, 541 U.S. at 196, 200-207 (uphold-
ing Congress’s authority to adjust tribal sovereignty in crimi-
nal matters under the Indian Commerce Clause without
considering the three-category framework).

   As with the Indian Commerce Clause, the Foreign Com-
merce Clause has followed its own distinct evolutionary path.
Born largely from a desire for uniform rules governing com-
mercial relations with foreign countries, the Supreme Court
has read the Foreign Commerce Clause as granting Congress
sweeping powers. See Bd. of Trustees of Univ. of Ill., 289 U.S.
at 59 (“[W]ith respect to foreign intercourse and trade[,] the
people of the United States act through a single government
with unified and adequate national power.”); see also Rotunda
& Nowak § 4.2 (“The Court has always recognized a plenary
power in Congress to deal with matters touching upon foreign
relations or foreign trade.”); Robert J. Delahunty, Federalism
Beyond the Water’s Edge: State Procurement Sanctions and
Foreign Affairs, 37 Stan. J. Int’l L. 1, 16-26 (2001) (describ-
ing the origins of the Foreign Commerce Clause). This view
was laid down nearly two centuries ago when Chief Justice
Marshall stated that “[i]t has, we believe, been universally
admitted, that [the words of the Commerce Clause] compre-
hend every species of commercial intercourse between the
United States and foreign nations.” Gibbons v. Ogden, 22
U.S. (9 Wheat) 1, 193 (1824).

  The Court has been unwavering in reading Congress’s
power over foreign commerce broadly. See, e.g., California
Bankers Ass’n v. Shultz, 416 U.S. 21, 46 (1974) (stating that
Congress’s plenary authority over foreign commerce “is not
                    UNITED STATES v. CLARK                  1023
open to dispute”); Buttfield v. Stranahan, 192 U.S. 470, 492-
93 (1904) (describing the “complete power of Congress over
foreign commerce”); Hartford Fire Ins. Co. v. California, 509
U.S. 764, 813-14 (1993) (Scalia, J., dissenting) (“Congress
has broad power under Article I, § 8, cl. 3, ‘to regulate Com-
merce with foreign Nations,’ and this Court has repeatedly
upheld its power to make laws applicable to persons or activi-
ties beyond our territorial boundaries where United States
interests are affected.”). There is no counterpart to Lopez or
Morrison in the foreign commerce realm that would signal a
retreat from the Court’s expansive reading of the Foreign
Commerce Clause. In fact, the Supreme Court has never
struck down an act of Congress as exceeding its powers to
regulate foreign commerce.

   Federalism and state sovereignty concerns do not restrict
Congress’s power over foreign commerce, see Japan Line,
441 U.S. at 448 n.13, and the need for federal uniformity “is
no less paramount” in assessing the so-called “dormant”
implications of congressional power under the Foreign Com-
merce Clause. Id. at 449; see also Bd. of Trustees of Univ. of
Ill., 289 U.S. at 59 (instrumentality of a state was not entitled
to import articles duty free because “with respect to foreign
intercourse and trade[,] the people of the United States act
through a single government with unified and adequate
national power”). By contrast, under the dormant Interstate
Commerce Clause, “reconciliation of the conflicting claims of
state and national power is to be attained only by some
appraisal and accommodation of the competing demands of
the state and national interests involved.” Southern Pac. Co.
v. Ariz. ex rel. Sullivan, 325 U.S. 761, 768-69 (1945).

   [6] Clark’s case illustrates the predominance of national
interests and the absence of state sovereignty concerns in For-
eign Commerce Clause jurisprudence. No state has voiced an
interest in the proceedings nor is there an indication of any
state interest at stake in determining the constitutionality of
§ 2423(c). Because this case is divorced from the common
1024                UNITED STATES v. CLARK
federal/state interplay seen in the Interstate Commerce Clause
cases, we find ourselves in sparsely charted waters. We thus
look to the text of § 2423(c) to discern whether it has a consti-
tutionally tenable nexus with foreign commerce.

  B.   SECTION 2423(C)’S REGULATION OF COMMERCIAL SEX
       ACTS IS A VALID EXERCISE OF CONGRESS’S FOREIGN
       COMMERCE CLAUSE POWERS

   Taking a page from Raich, we review the statute under the
traditional rational basis standard. Raich, 125 S.Ct. at 2211.
The question we pose is whether the statute bears a rational
relationship to Congress’s authority under the Foreign Com-
merce Clause.

   [7] Although it is important to view the statute as a whole,
parsing its elements illustrates why the statute fairly relates to
foreign commerce. The elements that the government must
prove under § 2423(c)’s commercial sex acts prong are
straightforward. First, the defendant must “travel[ ] in foreign
commerce.” 18 U.S.C. § 2423(c). Second, the defendant must
“engage[ ] in any illicit sexual conduct with another person,”
id., which in this case contemplates “any commercial sex act
. . . with a person under 18 years of age.” 18 U.S.C.
§ 2423(f)(2). We hold that § 2423(c)’s combination of requir-
ing travel in foreign commerce, coupled with engagement in
a commercial transaction while abroad, implicates foreign
commerce to a constitutionally adequate degree.

   [8] Beginning with the first element, the phrase “travels in
foreign commerce” unequivocally establishes that Congress
specifically invoked the Foreign Commerce Clause. The
defendant must therefore have moved in foreign commerce at
some point to trigger the statute. In Clark’s case, he traveled
from the United States to Cambodia.

  [9] “Foreign commerce” has been defined broadly for pur-
poses of Title 18 of the U.S. Code, with the statutory defini-
                    UNITED STATES v. CLARK                  1025
tion reading, in full: “The term ‘foreign commerce’, as used
in this title, includes commerce with a foreign country.” 18
U.S.C. § 10. Admittedly, this definition is not particularly
helpful given its rearrangement of the words being defined in
the definition itself. Courts have understandably taken the
broad wording to have an expansive reach. See, e.g., United
States v. Montford, 27 F.3d 137, 139-40 (5th Cir. 1994) (dis-
cerning that “Congress intended foreign commerce to mean
travel to or from, or at least some form of contact with, a for-
eign state”); Londos v. United States, 240 F.2d 1, 6 (5th Cir.
1957) (concluding that foreign commerce under § 10 “means
passing to and fro”). We likewise see no basis on which to
impose a constrained reading of “foreign commerce” under
§ 2423(c). Clark got on a plane in the United States and jour-
neyed to Cambodia. This act is sufficient to satisfy the “trav-
els in foreign commerce” element of § 2423(c).

   [10] Once in Cambodia, the second element of § 2423(c)
was also met, namely, “engage[ment] in any illicit sexual con-
duct with another person,” 18 U.S.C. § 2423(c), which in this
case was commercial sex under § 2423(f)(2). As the Supreme
Court recognized centuries ago, the Commerce Clause “com-
prehend[s] every species of commercial intercourse between
the United States and foreign nations.” Gibbons, 22 U.S. at
193; see also Bd. of Trustees of Univ. of Ill., 289 U.S. at 56-
57 (same). Section 2423(c) regulates a pernicious “species of
commercial intercourse”: commercial sex acts with minors.

   [11] The statute expressly includes an economic component
by defining “illicit sexual conduct,” in pertinent part, as “any
commercial sex act . . . with a person under 18 years of age.”
18 U.S.C. § 2423(f)(2). “Commercial sex act” is defined as
“any sex act, on account of which anything of value is given
to or received by any person.” 18 U.S.C. § 1591(c)(1). Thus,
in the most sterile terms, the statute covers the situation where
a U.S. citizen engages in a commercial transaction through
which money is exchanged for sex acts.
1026                   UNITED STATES v. CLARK
   [12] The essential economic character of the commercial
sex acts regulated by § 2423(c) stands in contrast to the non-
economic activities regulated by the statutes at issue in Lopez
and Morrison. See Morrison, 529 U.S. at 613 (“Gender-
motivated crimes of violence are not, in any sense of the
phrase, economic activity.”); Lopez, 514 U.S. at 561 (explain-
ing that firearm possession statute was purely a criminal stat-
ute). In both Lopez and Morrison, the Supreme Court voiced
strong concerns over Congress’s use of the Commerce Clause
to enact “a criminal statute that by its terms has nothing to do
with ‘commerce’ or any sort of economic enterprise, however
broadly one might define those terms.” Morrison, 529 U.S. at
610 (quoting Lopez, 514 U.S. at 561). Like the statute regulat-
ing illicit drugs at issue in Raich, the activity regulated by the
commercial sex prong of § 2423(c) is “quintessentially econom-
ic,”17 125 S. Ct. at 2211, and thus falls within foreign trade
and commerce.18
  17
      The evolving definition of “economics” presents a slight quirk to the
analysis. Although the definition in the 1966 Webster’s Third New Inter-
national Dictionary cited by the Supreme Court in Raich only refers to
“the production, distribution, and consumption of commodities,” more
recent versions of Webster’s have added “services” to the definition. See,
e.g., Merriam Webster’s Collegiate Dictionary 364 (10th ed. 1993) (defin-
ing “economics” as the social science concerned with “the production, dis-
tribution, and consumption of goods and services”); Merriam-Webster
Online Dictionary, available at www.m-w.com (same) (last visited Dec.
29, 2005).
   18
      It is now universally acknowledged that foreign trade or commerce
includes both goods and services. See, e.g., Agreement Establishing the
Multilateral Trade Organization [World Trade Organization], Dec. 15,
1993, 33 I.L.M. 13, pmbl. (“Recognizing that their relations in the field
of trade and economic endeavour should be conducted with a view to . . .
expanding the production and trade in goods and services”); General
Agreement on Trade in Services, Dec. 15, 1993, 33 I.L.M. 44, pmbl.
(“Recognizing the growing importance of trade in services for the growth
and development of the world economy”); cf. Gulf Oil Corp. v. Copp Pav-
ing Co., Inc., 419 U.S. 186, 195 (1974)(holding that, under the Interstate
Commerce Clause, the “ ‘in commerce’ language of the Clayton and
Robinson-Patman Act provisions . . . appears to denote only persons or
                       UNITED STATES v. CLARK                       1027
   As in Raich, the fact that § 2423(c) has a criminal as well
as an economic component does not put it beyond Congress’s
reach under the Foreign Commerce Clause. Indeed, § 2423(c)
is far from unique in using the Foreign Commerce Clause to
regulate crimes with an economic facet. See, e.g., United
States v. Kay, 359 F.3d 738, 741 (5th Cir. 2004) (describing
“particular instrumentalities of interstate and foreign com-
merce that defendants used or caused to be used in carrying
out the purported bribery” in violation of the Foreign Corrupt
Practices Act); United States v. Hsu, 155 F.3d 189, 195-96
(3rd Cir. 1998) (discussing statute enacted as part of the Eco-
nomic Espionage Act of 1996 that criminalizes the theft of
trade secrets related to products “produced for or placed in
interstate or foreign commerce”); United States v. Gertz, 249
F.2d 662, 666-67 (9th Cir. 1957) (explaining that statute
criminalizing the forging or counterfeiting of foreign currency
is based on the Foreign Commerce Clause).

   [13] The combination of Clark’s travel in foreign com-
merce and his conduct of an illicit commercial sex act in
Cambodia shortly thereafter puts the statute squarely within
Congress’s Foreign Commerce Clause authority. In reaching
this conclusion, we view the Foreign Commerce Clause inde-
pendently from its domestic brethren.

   Likewise, although our precedent illustrates that the inter-
state categories may be adapted for use in specific foreign
commerce contexts, see, e.g., Cummings, 281 F.3d at 1049
n.1, the categories have never been deemed exclusive or man-
datory, nor has the Supreme Court suggested their application
in relation to the Foreign Commerce Clause. Cf. Prakash, 55

activities within the flow of interstate commerce—the practical, economic
continuity in the generation of goods and services for interstate markets
and their transport and distribution to the consumer.”) (emphasis added).
But see Lopez, 514 U.S. at 585-89 (arguing that “commerce” as under-
stood at the time of the ratification of the Constitution encompassed only
bartering and trafficking in goods) (Thomas, J., concurring).
1028                UNITED STATES v. CLARK
Ark. L. Rev. at 1166 (“Apparently, the Supreme Court has
never discussed the applicability of the three-part Lopez test
to gauging the limits of the foreign commerce power.”). The
categories are a guide, not a straightjacket. In Cummings, we
upheld the constitutionality of the International Parental Kid-
naping Crime Act (“IPKCA”), 18 U.S.C. § 1204(a). See 281
F.3d at 1051. In so holding, we applied the interstate com-
merce framework but noted that Congress has “broader
power” in the foreign commerce area, and this context “is
quite relevant to our inquiry.” Id. at 1049 n.1. Critical to this
understanding was the Supreme Court’s now familiar state-
ment in Japan Line that “the Founders intended the scope of
the foreign commerce power to be . . . greater” as compared
with interstate commerce. Id. (quoting Japan Line, 441 U.S.
at 448).

   At times, forcing foreign commerce cases into the domestic
commerce rubric is a bit like one of the stepsisters trying to
don Cinderella’s glass slipper; nonetheless, there is a good
argument that, as found by the district court, § 2423(c) can
also be viewed as a valid regulation of the “channels of com-
merce.” Our previous decisions have recognized that Con-
gress legitimately exercises its authority to regulate the
channels of commerce where a crime committed on foreign
soil is necessarily tied to travel in foreign commerce, even
where the actual use of the channels has ceased. See Cum-
mings, 281 F.3d at 1050-51.

   Clark emphasizes that § 2423(b) requires that the foreign
travel be with the specific intent to engage in illicit sex,
whereas § 2423(c) does not have such a specific intent
requirement. Although the intent element distinguishes the
two statutory crimes, we do not see that it distinguishes the
scope of Congress’s Constitutional authority. Under
§ 2423(b), the crime is contained solely within the “travels in
foreign commerce” provision of the statute. Under the crime
charged in this case, § 2423(c) and (f)(2), the crime requires
both foreign travel and engaging in an illicit commercial sex
                   UNITED STATES v. CLARK                 1029
act. These are two different statutes with separate justifica-
tions under the Commerce Clause.

   [14] In sum, Clark has failed to demonstrate “a plain show-
ing that Congress . . . exceeded its constitutional bounds,”
Morrison, 529 U.S. at 607, in enacting §§ 2423(c) and (f)(2).
Traveling to a foreign country and paying a child to engage
in sex acts are indispensable ingredients of the crime to which
Clark pled guilty. The fact that §§ 2423(c) and (f)(2) meld
these economic and criminal components into a single statute
does not put the conduct beyond Congress’s reach under the
Foreign Commerce Clause. The rational nexus requirement is
met to a constitutionally sufficient degree. Congress did not
exceed its power “to regulate Commerce with foreign
Nations,” U.S. Const. art. I, § 8, cl. 3, in criminalizing com-
mercial sex acts with minors committed by U.S. citizens
abroad.

  AFFIRMED.



FERGUSON, Circuit Judge, dissenting:

   The Constitution cannot be interpreted according to the
principle that the end justifies the means. The sexual abuse of
children abroad is despicable, but we should not, and need
not, refashion our Constitution to address it. The majority
holds that “travel in foreign commerce, coupled with engage-
ment in a commercial transaction while abroad, implicates
foreign commerce to a constitutionally adequate degree.”
Maj. op. at 1024. I respectfully disagree.

  The Constitution authorizes Congress “[t]o regulate Com-
merce with foreign Nations.” Art. I, § 8, cl. 3. The activity
regulated by 18 U.S.C. § 2423(c), illicit sexual conduct, does
not in any sense of the phrase relate to commerce with foreign
nations. Rather, § 2423(c) is a criminal statute that punishes
1030                    UNITED STATES v. CLARK
private conduct fundamentally divorced from foreign com-
merce. Article I, section 8, clause 3, while giving Congress
broad authority over our commercial relations with other
nations, is not a grant of international police power. I respect-
fully dissent from the majority’s assertion that the Commerce
Clause authorizes Congress to regulate an activity with a bare
economic component, as long as that activity occurs subse-
quent to some form of international travel. I also note that the
conduct in this case will not go unpunished, as the reasonable
course of action remains of recognizing Cambodia’s authority
to prosecute Clark under its own criminal laws.

                                     I.

   Our national government is a government of “enumerated
powers,” see U.S. Const. art. I, § 8, which presupposes pow-
ers that are not enumerated, and therefore not accorded to
Congress, see Gibbons v. Ogden, 22 U.S. (9 Wheat.) 1, 85
(1824). As such, the Commerce Clause is “subject to outer
limits.” United States v. Lopez, 514 U.S. 549, 556-57 (1995).
Through a long line of cases, the Supreme Court has devel-
oped a tri-category framework that helps courts ascertain
these outer limits, and whether a particular enactment exceeds
them. See, e.g., Gonzales v. Raich, 125 S. Ct. 2195, 2205
(2005). In the foreign commerce context, the majority would
replace this time-tested framework with its own broad stan-
dard: whether a statute “has a constitutionally tenable nexus
with foreign commerce.” Maj. op. at 1024. The majority
views the foreign commerce prong of the Commerce Clause
“independently from its domestic brethren,” id. at 1027,
though Congress’s authority in both spheres is governed by
the same constitutional language: “[t]o regulate Commerce,”
art. I, § 8, cl. 3. In so doing, the majority goes farther than our
precedent counsels and dispenses with the tri-category frame-
work that has grounded Commerce Clause analysis in the
modern era.1
  1
   Though the majority asserts that it is applying “the traditional rational
basis standard,” maj. op. at 1024 (citing Raich, 125 S. Ct. at 2211), this
                        UNITED STATES v. CLARK                        1031
   The majority portrays the raison d’etre of the tri-category
framework as addressing “unique federalism concerns that
define congressional authority in the interstate context.” Maj.
op. at 1004 (emphasis added) (citing Lopez, 514 U.S. at 557).
It is thus able to conclude that this framework is generally
inapplicable to foreign commerce cases. A fairer understand-
ing of the tri-category framework is that it has evolved not
only in response to federalism concerns that courts have read
into Congress’s Interstate Commerce power, but also to give
content to what it means generally “[t]o regulate Commerce,”
art. I, § 8, cl. 3. Cf. Lopez, 514 U.S. at 551 (citing not only
federalism concerns in invalidating 18 U.S.C. § 922(q), but
also the fact that the statute “neither regulates a commercial
activity nor contains a requirement that the [gun] possession
be connected in any way to interstate commerce”); United
States v. Morrison, 529 U.S. 598, 610 (2000) (noting that “the
noneconomic, criminal nature of the conduct at issue” was
central to the Supreme Court’s decision in Lopez). While
Congress’s authority to regulate foreign commerce may well
be broader than its authority to regulate interstate commerce,
see, e.g., Japan Line, Ltd. v. County of Los Angeles, 441 U.S.
434, 448 (1979), its authority in the foreign sphere is not dif-
ferent in kind. In both spheres, Congress is only authorized
“[t]o regulate Commerce,” art. I, § 8, cl. 3, and not those
activities that are fundamentally divorced from commerce. So

statement is misleading to the extent that rationality review in the Com-
merce Clause context is applied as part of the “substantial effects” test,
which is a more demanding inquiry than the open-ended “nexus” inquiry
that the majority proposes. Compare Lopez, 514 U.S. at 561-63, with maj.
op. at 1024-29. Courts apply rationality review to assess whether Congress
had a “rational basis” for concluding that a particular activity “substan-
tially affects” interstate commerce, Raich, 125 S. Ct. at 2208, not to
inquire generally “whether the statute bears a rational relationship to Con-
gress’s authority under the [ ] Commerce Clause,” maj. op. at 1024. Raich
is further distinguished by the fact that Congress’s power to effectuate a
comprehensive regulatory scheme was central to that opinion, see 125
S. Ct. at 2206-07, while no comparably general regulation of foreign com-
merce exists in this case.
1032                  UNITED STATES v. CLARK
while the majority correctly notes that “[f]ederalism and state
sovereignty concerns do not restrict Congress’s power over
foreign commerce,” maj. op. at 1023, it fails properly to con-
sider the restrictions on the scope of Congress’s Foreign
Commerce power that emanate from the constitutional text
itself, which the tri-category framework also helps elucidate.

                                  II.

   Under the tri-category framework, and contrary to the Dis-
trict Court’s conclusion, § 2423(c) is not a regulation of the
channels of foreign commerce. Section 2423(c) lacks any of
the tangible links to the channels of commerce that would jus-
tify upholding it under Congress’s Foreign Commerce power.

   The Supreme Court has held that Congress’s authority to
regulate the channels of commerce encompasses keeping
those channels “free from immoral and injurious uses.” Heart
of Atlanta Motel, Inc. v. United States, 379 U.S. 241, 256
(1964) (internal quotation marks omitted). Thus, Congress has
the authority to criminalize the international transport of chil-
dren for the purpose of sexual exploitation in the U.S. because
such transport is an immoral and injurious use of the channels
of commerce. Cf. United States v. Hersh, 297 F.3d 1233, 1238
(11th Cir. 2002) (upholding the conviction of a defendant who
transported a Honduran boy to Florida to engage in sexual
relations). Congress also has the authority to criminalize
travel “for the purpose” of engaging in illicit sexual conduct,
since travel with such harmful intent constitutes an injurious
use of the channels of foreign commerce. See, e.g., United
States v. Bredimus, 352 F.3d 200, 207-08 (5th Cir. 2003).2 We
have not necessarily limited Congress’s reach under its chan-
nels of commerce authority based on the cessation of move-
ment. Thus, this Court found it a proper congressional
  2
  The statute upheld in Bredimus was the former 18 U.S.C. § 2423(b),
which preceded the present statute and which included an intent require-
ment.
                    UNITED STATES v. CLARK                   1033
exercise in United States v. Cummings to prevent persons
from retaining children abroad after they first made use of the
channels of foreign commerce wrongfully to remove the chil-
dren from the U.S. 281 F.3d 1046, 1050 (9th Cir. 2002); see
also United States v. Shahani-Jahromi, 286 F. Supp. 2d 723,
734 (E.D. Va. 2003) (holding that wrongful retention of a
child in a foreign country, which impeded that child’s travel
back to the U.S. through the channels of commerce, provided
a sufficient basis for Congress to exercise its Foreign Com-
merce power).

   Under this rubric, the current 18 U.S.C. § 2423(b) contains
a defensible link to the channels of foreign commerce, as it
covers people who “[t]ravel with intent to engage in illicit
sexual conduct.” See, e.g., Nick Madigan, Man, 86, Convicted
Under New Law Against Americans Who Go Abroad to
Molest Minors, N.Y. Times, Nov. 20, 2004, at A12 (defendant
was arrested at Los Angeles International Airport with “doz-
ens of pornographic photographs of himself with Filipino
girls, sex toys and 100 pounds of chocolate and candy”). The
activity regulated by § 2423(b), intention to engage in illicit
sexual conduct, is at least tenably related to the channels of
commerce in that the defendant engages in travel with illegiti-
mate ends. The person indicted under § 2423(b) has a plane
ticket in hand, has paid a travel agent to set up the trip, or has
otherwise committed an act that is both wrongful (because of
the criminal intent) and tangibly related to the channels of
commerce.

   By contrast, § 2423(c) neither punishes the act of traveling
in foreign commerce, or the wrongful use or impediment of
use of the channels of foreign commerce. Rather, it punishes
future conduct in a foreign country entirely divorced from the
act of traveling except for the fact that the travel occurs at
some point prior to the regulated conduct. The statute does
not require any wrongful intent at the time the channel is
being used, nor does it require a temporal link between the
1034                UNITED STATES v. CLARK
“travel[ ] in foreign commerce,” 18 U.S.C. § 2423(c), and the
underlying regulated activity.

   The majority suggests that § 2423(c) “can [ ] be viewed as
a valid regulation of the ‘channels of commerce,’ ” maj. op.
at 1028, because Congress’s channels of commerce authority
extends to regulating crimes committed abroad that are “nec-
essarily tied to travel in foreign commerce,” id. But whereas
the requisite ties to the channels of commerce exist in the case
the majority cites, Cummings, 281 F.3d 1046, these ties are
entirely absent in § 2423(c). The statute in Cummings prohib-
ited conduct — wrongful retention of children abroad — that
was necessarily tied to injurious uses of the channels of com-
merce. The defendant in Cummings illegally transported his
children to Germany so that he could retain them there, and
his wrongful retention of them necessarily impeded their law-
ful use of the channels of commerce to return to the U.S. By
contrast, § 2423(c) regulates an activity that is in no way con-
nected to the wrongful use, or impediment of use, of the chan-
nels of foreign commerce. Section 2423(c) only requires that
the regulated conduct occur at some point subsequent — per-
haps even years subsequent — to international travel. The
travel may well be lawful — the statute does not require any
criminal intent during travel, nor does it otherwise connect the
regulated activity to an abuse of the channels of commerce.

   The mere act of boarding an international flight, without
more, is insufficient to bring all of Clark’s downstream activi-
ties that involve an exchange of value within the ambit of
Congress’s Foreign Commerce power. On some level, every
act by a U.S. citizen abroad takes place subsequent to an
international flight or some form of “travel[ ] in foreign com-
merce.” 18 U.S.C. § 2423(c). This cannot mean that every act
with a bare economic component that occurs downstream
from that travel is subject to regulation by the United States
under its Foreign Commerce power, or the Commerce Clause
will have been converted into a general grant of police power.
It is telling to note that, theoretically, the only U.S. citizens
                    UNITED STATES v. CLARK                  1035
who could fall outside the reach of § 2423(c) if they engage
in illicit sexual conduct abroad are those who never set foot
in the United States (i.e., U.S. citizens by virtue of their par-
ent’s citizenship), and thus never travel in “Commerce with
foreign Nations.” Art. I, § 8, cl. 3. In short, § 2423(c) is
divorced from its asserted Commerce Clause underpinnings.
The statute does not set another “guidepost” regarding Con-
gress’s Foreign Commerce power, contra United States v.
Clark, 315 F. Supp. 2d 1127, 1135 (W.D. Wash. 2004) — it
exceeds it.

                              III.

   Rather than engaging in a losing “channels of commerce”
analysis, the majority applies a general “rational nexus” stan-
dard in this case, maj. op. at 1029, and strains to find more
foreign commerce in § 2423(c) than the act of boarding an
international flight. Specifically, the majority characterizes
the crime regulated by § 2423(c), illicit sexual conduct, as
sufficiently related to “Commerce with foreign Nations,” art.
I, § 8, cl. 3, to bring it under Congress’s Foreign Commerce
authority.

   First, the underlying regulated activity is not “quintessen-
tially economic,” maj. op. at 1026, simply because it has a
bare economic aspect. Just as “[g]ender-motivated crimes of
violence are not, in any sense of the phrase, economic activi-
ty,” Morrison, 529 U.S. at 613, neither is “illicit sexual con-
duct.” The plain purpose of § 2423(c) is to regulate criminal
conduct, not commerce. As the Supreme Court cautioned in
Lopez, “depending on the level of generality, any activity can
be looked upon as commercial.” 514 U.S. at 565.

   Further, the underlying act, even if considered economic or
commercial, is certainly not a presence of commerce with for-
eign nations. In the most sterile terms, an act of paid sex with
a minor that takes place overseas is not an act of commerce
with other nations. Under the interpretation of the majority,
1036                UNITED STATES v. CLARK
the purchase of a lunch in France by an American citizen who
traveled there by airplane would constitute a constitutional act
of engaging in foreign commerce. Under such an interpreta-
tion, Congress could have the power to regulate the overseas
activities of U.S. citizens many months or years after they had
concluded their travel in foreign commerce, as long as the
activities involved some sort of exchange of value — even if
the partner in exchange was a U.S. entity that funneled the
value back into the American economy. Analogously, the stat-
ute here does not even facially limit its application to sex with
foreign minors in an effort to create a tenable link to “Com-
merce with foreign Nations.” Art. I, § 8, cl. 3. This observa-
tion may seem slightly absurd, but so is the task of trying to
show how sexual abuse of a minor overseas by a U.S. citizen
constitutes an act of “Commerce with foreign Nations.” Id.

                              IV.

   Viewed as a whole, it is clear that § 2423(c) does not relate
to “Commerce with foreign Nations.” Id. Nor is § 2423(c) a
constitutional exercise of Congress’s authority to regulate the
channels of commerce. Sexual exploitation of children by for-
eigners is thoroughly condemnable, but the question before us
is whether Congress properly invoked its power “[t]o regulate
Commerce with foreign Nations,” id., in enacting § 2423(c) to
address this problem. It did not. I therefore respectfully dis-
sent.
