Full opinion text
Opinion for the Court by Circuit Judge ROGERS. Opinion dissenting in part by Circuit Judge KAVANAUGH. ROGERS, Circuit Judge: Pursuant to a contract with the Indonesian government, Exxon Mobil Corporation, a United States corporation, and several of its wholly owned subsidiaries (hereinafter “Exxon”) operated a large natural gas extraction and processing facility in the Aceh province of Indonesia in 2000-2001. Plaintiffs-appellants are fifteen Indonesian villagers from the Aceh territory. Eleven villagers filed a complaint in 2001 alleging that Exxon’s security forces committed murder, torture, sexual assault, battery, and false imprisonment in violation of the Alien Tort Statute (“ATS”) and the Torture Victim Protection Act (“TVPA”), and various common law torts. (The Doe I complaint.) Four other Aceh villagers alleged in 2007 that Exxon committed various common law torts. (The Doe VIII complaint.) All plaintiffs-appellants allege that Exxon took actions both in the United States and at its facility in the Aceh province that resulted in their injuries. The district court dismissed the statutory claims, see Doe I v. Exxon Mobil Corp., 393 F.Supp.2d 20 (D.D.C.2005), and discovery proceeded on the tort claims. Those claims, however, were subsequently dismissed for lack of prudential standing. See Doe VIII v. Exxon Mobil Corp., 658 F.Supp.2d 131 (D.D.C.2009). Plaintiffs-appellants challenge the dismissals of their complaints and Exxon filed a cross-appeal, inter alia raising for the first time that as a corporation it was immune from liability under the ATS. For the reasons that follow, we conclude that aiding and abetting liability is well established under the ATS. We further conclude under our precedent that this court should address Exxon’s contention on appeal of corporate immunity and, contrary to its view and that of the Second Circuit, we join the Eleventh Circuit in holding that neither the text, history, nor purpose of the ATS supports corporate immunity for torts based on heinous conduct allegedly committed by its agents in violation of the law of nations. We affirm the dismissal of the TVPA claims in view of recent precedent of this court. We conclude, however, that Exxon’s objections to justiciability are unpersuasive and that the district court erred in ruling that appellants lack prudential standing to bring their non-federal tort claims and in the choice of law determination. Finally, we conclude that Exxon’s challenge to the diversity of parties in the Doe VIII complaint is to be resolved initially by the district court. Therefore, we affirm the dismissal of plaintiffs-appellants’ TVPA claims, reverse the dismissal of the ATS claims at issue in this appeal, along with plaintiffs-appellants’ non-federal tort claims, and remand the cases to the district court. I. Accepting the allegations of the complaints as true, and construing the complaints in favor of plaintiffs-appellants, as we must, see Warth v. Seldin, 422 U.S. 490, 501, 95 S.Ct. 2197, 45 L.Ed.2d 343 (1975), the plaintiffs claim that Exxon’s security forces were comprised of members of the Indonesian military and that Exxon and its subsidiaries, which were incorporated at the time of the filing of the first complaint in New Jersey and Delaware, Doe I Compl. ¶¶ 17, 20, 23, retained these soldiers as guards for its natural gas facility even though Exxon was aware that the Indonesian army had committed human rights abuses in the past, id. ¶¶ 39-47; Doe I Am. Compl. ¶¶ 55-66; Doe VIII Compl. ¶¶ 39-59, and knew that performance of the security contract would lead to human rights violations by Indonesian soldiers against the residents of Aceh. Doe I Compl. ¶¶ 64, 71; Doe I Am. Compl. ¶¶,60, 66, 125; Doe VIII Compl. ¶¶ 51-53, 79. The human rights abuses alleged included genocide, extrajudicial killing, torture, crimes against humanity, sexual violence, and kidnaping. Doe I Compl. ¶ 64. In addition to extrajudicial killings of some of the plaintiffs-appellants’ husbands as part of a “systematic campaign of extermination of the people of Aceh, by [defendants’ [Indonesian] security forces,” id. ¶ 65, the plaintiffs-appellants were “beaten, burned, shocked with cattle prods, kicked and subjected to other forms of brutality and cruelty” amounting to torture, id. ¶ 66, as well as forcibly removed and detained for lengthy periods of time, id. ¶ 67. Plaintiffs-appellants claim that Exxon or its agents, by decisions made in the United States, id. ¶¶ 30, 32-33, and at its Aceh plant, id. ¶¶ 55-57, “committed acts that had the intent and the effect of grossly humiliating and debasing” either them or their deceased husbands by “forcing them to act against them will and conscience, inciting fear and anguish, and breaking their physical and/or moral resistance” by actions that constitute “inhuman or degrading treatment in violation of the law of nations.” Id. ¶ 68. According to the complaints, these actions of the Indonesian military could be attributed to Exxon because they were committed by a unit dedicated only to Exxon’s Aceh facility and Exxon had the authority “to control and direct[ ]” the soldiers’ actions. Id. ¶40. Plaintiffs-appellants claim Exxon was aware of the atrocities committed by the Indonesian military in Aceh, as confirmed by public reports including reports of atrocities committed by Exxon’s dedicated unit, and that Exxon nonetheless provided logistical and material support to the military by hiring mercenaries to provide advice, training, intelligence, and equipment to the unit while Exxon profited from the operation of its Aceh facility. Id. ¶¶ 39-41, 46. By acting together with Indonesian security forces, the plaintiffs-appellants claim that Exxon acted under color of Indonesian law. Id. On October 1, 2001, Exxon moved to dismiss the complaint, and after a hearing on the motion the district court requested the Office of Legal Adviser of the Department of State to inform the court whether the Department deemed adjudication of the case to affect adversely the interests of the United States. On July 29, 2002, the Office of Legal Adviser filed a statement of interest and attached a statement of the Indonesian Ambassador to the United States. Thereafter, the district court dismissed the statutory claims. It ruled that aiding and abetting was not actionable under the ATS, Doe I, 393 F.Supp.2d at 24, that “sexual violence” is not sufficiently recognized as a violation of the law of nations to be actionable under the ATS, and that Exxon could not be. liable for genocide and crimes against humanity because adjudication of such claims would “be an impermissible intrusion in Indonesia’s internal affairs.” Id. at 25. Although concluding that “resolving claims of complicity in arbitrary detention, torture, and extrajudicial killing pose[d] less of a threat of infringing Indonesia’s sovereignty,” id., the district court ruled that the plaintiffs could not assert such claims against Exxon because color-of-law jurisprudence developed in lawsuits under 42 U.S.C. § 1983 was inapplicable in view of Sosa v. Alvarez-Machain, 542 U.S. 692, 124 S.Ct. 2739, 159 L.Ed.2d 718 (2004). Doe I, 393 F.Supp.2d at 25-26. The district court also ruled that joint action with the Indonesian military was not sufficiently alleged, but even if it were the required inquiry would raise justiciability concerns, and to the extent state action could be alleged under a proximate cause theory, that theory was not sufficiently alleged in the complaint. Id. at 26-27. The district court declined to hold, as Exxon urged, that the ATS claims must be dismissed due to plaintiffs-appellants’ failure to exhaust remedies in Indonesia because it was apparent that such efforts would be futile. Id. at 24-25. On appeal, plaintiffs-appellants challenge the dismissal of their ATS and TVPA claims based on prohibitions of extrajudicial killing, torture, and prolonged arbitrary detention, but do not appeal the dismissal of their claims of genocide, crimes against humanity, or sexual violence. They contend, and Exxon does not dispute, that extrajudicial killing, torture, and prolonged arbitrary detention are clearly established norms of international law. They also contend, but Exxon disputes, that the district court erred in ruling that aiding and abetting liability is unavailable under the ATS, in view of subsequent case law in the circuit courts of appeals, and in ruling that color-of-law jurisprudence may not be applied in ATS cases. Responding to Exxon’s new contention on appeal that it is entitled to corporate immunity because customary international law does not recognize corporate liability for human rights violations, appellants contend that Exxon has conflated Sosa’s analysis for norms in a manner that is inconsistent with a well-established distinction in international law, and alternatively it has inaccurately recounted customary international law. Appellants maintain that corporations may be liable directly and also for aiding and abetting under the ATS and the TVPA. Finally, appellants challenge the dismissal of their non-federal tort claims, contending that history demonstrates that there is no per se bar on non-resident alien standing and that they meet the traditional zone-of-interests test for prudential standing. Exxon maintains that appellants cannot meet the zone-of-interests test because the alleged torts occurred on foreign soil and that any state law claims would be subject to foreign affairs preemption, and even if those claims survive, Indonesian law ought to apply. Exxon also raises three justiciability objections: the complaint should be dismissed in deference to the foreign policy views of the Executive Branch; the claims interfere with a peace agreement supported by the United States; and the claims threaten international comity with Indonesia. Exxon further maintains the Doe VIII complaint must be dismissed for lack of diversity jurisdiction. In Part II, we address aiding and abetting liability under the ATS, concluding that it is well established. In Part III, we examine Exxon’s claim of corporate immunity, concluding that corporations can be held liable under the ATS. In Part IV, we affirm the dismissal of appellants’ claims under the TVPA in view of precedent issued by this court after oral argument in these cases. In Part V, we consider Exxon’s contentions that the complaints should be dismissed on justiciability grounds and find them unpersuasive. In Part VI, we resolve appellants’ challenge to the dismissal of their common law claims for lack of prudential standing, concluding that they have such standing; we agree, however, with Exxon that the district court erred in its choice of law determination and that Indonesian law applies under the District of Columbia choice of law rule to appellants’ non-federal tort claims. In Part VII, we remand to the district court questions raised by Exxon with regard to the existence of diversity jurisdiction in Doe VIII. We conclude that none of the four reasons offered by our dissenting colleague for reaching a different conclusion about the reach of the ATS withstand analysis. The dissent’s first objection relates to extraterritoriality when that issue is not presented and, as the historical context makes clear, the ATS reaches harm occurring outside of the United States. The dissent’s objection to corporate liability is based on a misstatement of the definition of customary international law and of Supreme Court precedent, and disregards both a fundamental distinction between causes of action based on conduct that violates the law of nations or treaties and the remedy under domestic law, and a source of international law. The dissent’s third objection that the TVPA precludes the court’s conclusions regarding the ATS is contrary to the Supreme Court’s conclusion about the effect of the TVPA on the ATS and inappropriately addresses an argument forfeited by Exxon. Finally, the dissent’s justiciability objection selectively characterizes not only the complaints but also the State Department’s expression of interest in this litigation. II. The ATS stood largely dormant for nearly two centuries after its enactment in 1789. Two district courts invoked jurisdiction under the ATS. See Adra v. Clift, 195 F.Supp. 857 (D.Md.1961); Bolchos v. Darrel, 3 F.Cas. 810 (D.S.C.1795) (No. 1,607). The first appellate court to uphold a claim under the ATS did so in 1980 when the Second Circuit held in Filartiga v. Pena-Irala, 630 F.2d 876 (2d Cir.1980), that deliberate torture perpetrated under color of official authority violated universally accepted norms of international law on human rights and that the ATS provided federal jurisdiction over a claim by a resident alien against a Paraguayan official for the death of his son in Paraguay. The Supreme Court in Sosa described Filartiga as “the birth of the modern line of [ATS] cases.” 542 U.S. at 724-25, 124 S.Ct. 2739. Even after Filartiga, however, courts and commentators continued to disagree as to the proper interpretation of the ATS, resulting in the exchange between Judge Edwards and Judge Bork in Tel-Oren v. Libyan Arab Republic, 726 F.2d 774 (D.C.Cir.1984). The Supreme Court in Sosa settled this disagreement, adopting an approach consistent with both Filartiga and Judge Edwards’ separate opinion in Tel-Oren. The issue in Sosa was whether a Mexican citizen (Alvarez-Machain) could bring a claim under the ATS against Mexican nationals hired by the U.S. Drug Enforcement Administration (“DEA”) for an alleged violation of the law of nations arising from his “arbitrary arrest.” DEA agents had obtained an arrest warrant from a U.S. district court and hired Mexican nationals (including Sosa) to abduct AlvarezMachain and bring him to the United States to be arrested. 542 U.S. at 698, 124 S.Ct. 2739. The Supreme Court, although concluding the ATS was “intended as jurisdictional,” id. at 714, 124 S.Ct. 2739, and “creatfed] no new causes of action,” id. at 724, 124 S.Ct. 2739, held that “[t]he jurisdictional grant is best read as having been enacted on the understanding that the common law would provide a cause of action for the modest number of international law violations with a potential for personal liability at the time,” id. Further, the Court concluded that “Congress has not in any relevant way amended § 1350 or limited civil common law power by another statute.” Id. at 725, 124 S.Ct. 2739. The Court went on to observe, as we discuss in Part V, that “there are good reasons for a restrained conception of the discretion a federal court should exercise in considering a new cause of action of this kind.” Id. Upon considering the history and purpose of the ATS, the Supreme Court instructed that “courts should require any claim based on the present-day law of nations to rest on a norm of international character accepted by the civilized world and defined with a specificity comparable to the features of the 18th-century paradigms we have recognized,” id., referencing violation of safe conducts, infringement of the rights of ambassadors, and piracy, id. at 724, 124 S.Ct. 2739. The Court recognized that “a judge deciding in reliance on an international norm will find a substantial element of discretionary judgment in the decision,” id. at 726, 124 S.Ct. 2739, but admonished that “federal courts should not recognize private claims under federal common law for violations of any international law norm with less definite content and acceptance among civilized nations than the historical paradigms familiar when § 1350 was enacted,” id. at 732, 124 S.Ct. 2739. Appellants’ aiding and abetting contention meets this test. In dismissing appellants’ statutory claims, the district court relied principally on In re South African Apartheid Litigation, 346 F.Supp.2d 538, 549-51 (S.D.N.Y. 2004), which held that private actors who did not engage in state action committed no violation remediable under the ATS. That authority was overruled in Khulumani v. Barclay National Bank Ltd., 504 F.3d 254 (2d Cir.2007), aff'd for lack of en banc quorum sub nom., Am. Isuzu Motors, Inc. v. Ntsebeza, 553 U.S. 1028, 128 S.Ct. 2424, 171 L.Ed.2d 225 (2008); see also Presbyterian Church of Sudan v. Talisman Energy, Inc., 582 F.3d 244, 256 (2d Cir.2009), cert. denied, — U.S. -, 131 S.Ct. 79, 178 L.Ed.2d 241 (2010). The district court also ruled that there was no liability for aiding and abetting under the ATS, applying the rule of statutory construction in Central Bank of Denver v. First Interstate Bank of Denver, 511 U.S. 164, 181-82, 114 S.Ct. 1439, 128 L.Ed.2d 119 (1994), superseded in part by statute, 15 U.S.C. § 78t(e), that there is no general presumption in favor of aiding and abetting liability. Doe I, 393 F.Supp.2d at 24. Appellants persuasively contend that aiding and abetting liability exists under the ATS. Virtually every court to address the issue, before and after Sosa, has so held, recognizing secondary liability for violations of international law since the founding of the Republic. Appellants cite as examples Talbot v. Jansen, 3 U.S. (3 Dall.) 133, 167-68, 1 L.Ed. 540 (1795) (Iredell, J.), The Amiable Nancy, 1 F. Cas. 765, 768 (C.C.D.N.Y.1817) (No. 331), and Henfield’s Case, 11 F. Cas. 1099 (C.C.D.Pa.1793) (No. 6,360). Further, they note that aiding and abetting liability was a common feature of Founding-era statutes addressing international law offenses, see Crimes Act of 1790, ch. 9, § 10, 1 Stat. 112, 114 (1790) (deeming “an accessary [sic] to ... piracies” anyone who “knowingly and willingly aided” piracy). Exxon maintains, however, that there is no aiding and abetting liability under the ATS because of the presumption against extraterritorial application established at the time of the ATS’s enactment, and the Supreme Court’s instruction in Central Bank, 511 U.S. at 181-82, 114 S.Ct. 1439, that although “aiding and abetting is an ancient criminal law doctrine,” id. at 181, 114 S.Ct. 1439, “when Congress enacts a statute under which a person may sue and recover damages from a private defendant for the defendant’s violation of some statutory norm, there is no general presumption that the plaintiff may also sue aiders and abettors,” id. at 182, 114 S.Ct. 1439. For the following reasons, we hold that there is no extraterritoriality bar as Exxon suggests, that the principle of aiding and abetting liability is well established in customary international law, and that the mens rea and actus reus requirements are those set out by the Nuremberg Tribunals and the international courts created by the United Nations, which reflect the standard under federal common law. A. The issue of extraterritoriality, although briefed, was not decided in Sosa, and it has yet to be decided by a circuit court of appeals. One judge of this court discussed the issue in Tel-Oren, looking to the then-tentative draft Restatement of the Foreign Relations Law of the United States, 726 F.2d at 781 n. 7, 788 (Edwards, J., concurring), which in its final version states that a nation has universal jurisdiction to define and prescribe punishment for certain egregious crimes regardless of any territorial considerations, Restatement (Third) of Foreign Relations Law of the United States § 404, and otherwise a nation may prescribe law as to conduct occurring or having an effect in its territory and “the activities, interests, status, or relations of its nationals outside as well as within its territory,” id. § 402(l)-(2); see also Sosa, 542 U.S. at 761, 124 S.Ct. 2739 (Breyer, J., concurring) (citing Restatement (Third) of Foreign Relations Law of the United States § 401(l)-(2)). The two other judges in Teh-Oren and our recent decision in Ali Shafi v. Palestinian Authority, 642 F.3d 1088 (D.C.Cir.2011), relied on other grounds for dismissing the ATS claims, notwithstanding that both involved claims of harms occurring outside of the United States, as did the claims in Sosa and Filartiga. The Supreme Court, however, recently reaffirmed the “presumption against extraterritoriality” in Morrison v. National Australia Bank Ltd., — U.S. -, 130 S.Ct. 2869, 177 L.Ed.2d 535 (2010), holding that “[rjather than guess anew in each case, we apply the presumption in all cases, preserving a stable background against which Congress can legislate with predictable effects.” Id. at 2881. “This principle represents a canon of construction, or a presumption about a statute’s meaning.” Id. at 2877. “When a statute gives no clear indication of an extraterritorial application, it has none.” Id. at 2878. The ATS provides in full: The district courts shall have original jurisdiction of any civil action by an alien for a tort only, committed in violation of the law of nations or a treaty of the United States. 28 U.S.C. § 1350. The ATS was enacted as part of the Judiciary Act of 1789, ch. 20, § 9, 1 Stat. 73, 77 (1789), and its content has not been materially amended since its enactment. Its terms are “jurisdictional,” the Supreme Court held in Sosa, “enabling] federal courts to hear claims in a very limited category defined by the law of nations and recognized at common law.” 542 U.S. at 712, 124 S.Ct. 2739. At the time of enactment of the ATS, the Court observed, “torts in violation of the law of nations were understood to be within the common law.” Id. And although the Supreme Court has fundamentally altered the breadth and understanding of federal common law since the ATS’s enactment, see id. at 729, 124 S.Ct. 2739 (citing Erie R.R. Co. v. Tompkins, 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188 (1938)), the Court noted in Sosa that in certain areas federal common law will prevail either because of express congressional authorization to devise a body of law, see id. at 726, 124 S.Ct. 2739 (citing Textile Workers v. Lincoln Mills of Ala., 353 U.S. 448, 77 S.Ct. 912, 1 L.Ed.2d 972 (1957)), or by way of judicial decision “to create federal common law rules in interstitial areas of particular federal interest,” id. (citing United States v. Kimbell Foods, Inc., 440 U.S. 715, 726-27, 99 S.Ct. 1448, 59 L.Ed.2d 711 (1979)). The Court concluded that the ATS was enacted on the basis of a “congressional assumption” that courts would develop common law claims “derived from the law of nations,” thus ensuring that any common lawmaking authority as to actionable conduct would, at least, be cabined by the law of nations. Id. at 731 n. 19, 124 S.Ct. 2739. Citing Morrison, Exxon contends that a “strong presumption ... against extending [federal statutes] to encompass conduct in foreign territory” militates against recognizing a common law aiding and abetting claim based on human rights violations committed in a foreign country. Appellees’ Br. 37. Exxon posits a novel form of the canon, for it appears beyond debate that piracy is contemplated by the ATS, see Sosa, 542 U.S. at 719, 124 S.Ct. 2739; Tel-Oren, 726 F.2d at 779 (Edwards, J., concurring) (citing 4 Blackstone’s Commentaries *67); id. at 813-14 (Bork, J., concurring), and piracy can occur outside of the territorial bounds of the United States, see generally United States v. Hasan, 747 F.Supp.2d 599 (E.D.Va.2010), and, the Supreme Court has held, also within the territorial waters of another nation, see United States v. Furlong, 18 U.S. (5 Wheat.) 184, 200-01, 5 L.Ed. 64 (1820). Morrison and other Supreme Court cases hold, in contrast to Exxon’s canon, “that legislation of Congress, unless a contrary intent appears, is meant to apply only within the territorial jurisdiction of the United States.” 130 S.Ct. at 2877 (quoting EEOC v. Arabian Am. Oil Co. (“ARAMCO ”), 499 U.S. 244, 248, 111 S.Ct. 1227, 113 L.Ed.2d 274 (1991)); see also Foley Bros., Inc. v. Filardo, 336 U.S. 281, 285, 69 S.Ct. 575, 93 L.Ed. 680 (1949); Blackmer v. United States, 284 U.S. 421, 437, 52 S.Ct. 252, 76 L.Ed. 375 (1932); United States v. Bowman, 260 U.S. 94, 98-99, 43 S.Ct. 39, 67 L.Ed. 149 (1922). It is at least arguable that none of the modern cases cited by Exxon (and our dissenting colleague, Dis. Op. at 74-76) interpret statutes having obvious extraterritorial reach, as the dissent, concedes is true of the ATS, see Dis. Op. at 78-79. “This principle [of a presumption against extraterritorial reach of a statute] represents a canon of construction ... rather than a limit upon Congress’s power to legislate.” Morrison, 130 S.Ct. at 2877. Exxon’s characterization of the presumption against extraterritoriality is incomplete at best, stating the presumption is “against extending [federal statutes] to encompass conduct in foreign territory.” Appellees’ Br. 37. Exxon has cited no authority supporting the existence of a presumption that a statute applies to the high seas (e.g., piracy) but not to foreign territory; indeed, Exxon cites two Supreme Court cases supporting the con- trary: The Apollon, 22 U.S. (9 Wheat.) 362, 370, 6 L.Ed. 111 (1824), and Rose v. Himely, 8 U.S. (4 Cranch) 241, 279, 2 L.Ed. 608 (1808). In The Apollon the Court held that “[t]he laws of no nation can justly extend beyond its own territories, except so far as regards its own citizens,” 22 U.S. at 370 (emphasis added), and in Rose v. Himely “that the legislation of every country is territorial; that beyond its own territory, it can only affect its own subjects or citizens,” 8 U.S. at 279 (emphasis added). To the extent Exxon maintains that the ATS is only partially extraterritorial, it advocates a novel canon of statutory construction, and not one of the settled “background canons of interpretation of which Congress is presumptively aware” when it legislates. Lockhart v. United States, 546 U.S. 142, 148, 126 S.Ct. 699, 163 L.Ed.2d 557 (2005). Our dissenting colleague would bifurcate the canon by requiring a separate query with respect to the high seas and foreign countries. The dissent posits that because piracy by definition occurs on the high seas, application of the canon against extraterritoriality — as that canon has been consistently defined by the Supreme Court for over two hundred years — creates a statutory outcome that is at odds with congressional intent that the ATS grant federal courts jurisdiction over aliens’ piracy-related torts. Dis. Op. at 78-79. Finding the existing canon of no avail, the dissent mutates both the canon and the precedent into a new canon that produces the desired result. To the extent that a canon of construction draws its persuasiveness in large measure from the fact that Congress is “presumptively aware,” Lockhart, 546 U.S. at 148, 126 S.Ct. 699, of such canons of outstanding vintage when it legislates and thus “preserves] a stable background against which Congress can legislate with predictable effects,” Morrison, 130 S.Ct. at 2878, a newly minted canon fashioned in a dissenting opinion more than two hundred years after the First Congress provides no such benefit. Further, a technical but nonetheless important point sheds light on Exxon’s contentions: appellants are not asking this court to apply the ATS itself extraterritorially. In Sosa, the Supreme Court held that the ATS is a jurisdictional statute that provides U.S. district courts with jurisdiction over civil actions brought by aliens seeking relief for torts committed in violation of the law of nations, and does not itself create causes of action. 542 U.S. at 713-14, 124 S.Ct. 2739; 28 U.S.C. § 1350. As a jurisdictional statute, it would apply extraterritorially only if Congress were to establish U.S. district courts in foreign countries. To say that a court is applying the ATS extraterritorially when it hears an action such as appellants have brought makes no more sense than saying that a court is applying 28 U.S.C. § 1331, the federal question statute, extraterritorially when it hears a TVPA claim brought by a U.S. citizen based on torture in a foreign country. Thus, the question here is not whether the ATS applies extraterritorially but is instead whether the common law causes of action that federal courts recognize in ATS lawsuits may extend to harm to aliens occurring in foreign countries. One might hope to resolve this question by considering whether the First Congress would have understood federal courts to have the authority to recognize such causes of action. Unfortunately, the historical record with respect to this question is sparse and has been characterized as ambiguous. The authority most on point is a 1795 legal opinion by U.S. Attorney General William Bradford. See Breach of Neutrality, 1 Op. Att’y Gen. 57 (1795). In the midst of the war between Britain and France that followed the French Revolution, U.S. citizens participated in a French privateer fleet’s attack and plunder of the British colony of Sierra Leone in 1794. See id. at 58. Responding to a protest from the British Ambassador, Attorney General Bradford expressed “some doubt” as to whether the U.S. citizens could be prosecuted in U.S. courts. See id. at 58-59. But Bradford had “no doubt that the company or individuals who ha[d] been injured by the[ ] acts of hostility ha[d] a remedy by a civil suit in the courts of the United States” since Congress in the ATS had granted federal courts “jurisdiction ... in all cases where an alien sues for a tort only, in violation of the laws of nations, or a treaty of the United States.” Id. at 59 (emphasis in original). Bradford’s opinion, however, is not a model of clarity. The paragraph containing Bradford’s discussion of the ATS opens by stating, “So far ... as the transactions complained of originated or took place in a foreign country, they are not within the cognizance of our courts.... ” Id. at 58. In context, this statement might be best read as applying only to the scope of the U.S. courts’ criminal jurisdiction. The majority in the Second Circuit, however, interpreted the statement more broadly, citing it as support for the proposition that at the time of its enactment, the ATS was not understood to grant federal courts jurisdiction over international law violations committed within the territorial jurisdiction of foreign nations but “only for the actions taken by Americans on the high seas.” See Kiobel v. Royal Dutch Petroleum Co., 621 F.3d 111, 142 n. 44 (2d Cir.2010). In Sosa the Supreme Court viewed the Attorney General’s opinion as “clear that a federal court was open for the prosecution of a tort action growing out of the episode,” 542 U.S. at 721, 124 S.Ct. 2739, but noted uncertainty about whether Bradford assumed there had been a violation of a treaty and concluded that “it appears likely Bradford understood the ATS to provide jurisdiction over what must have ‘ amounted to common law causes of action,” id. Extraterritorial application of the ATS would reflect the contemporaneous understanding that, by the time of the Judiciary Act of 1789, a transitory tort action arising out of activities beyond the forum state’s territorial limits could be tried in the forum state. See Stoddard v. Bird, 1 Kirby 65, 68 (Conn.Super.Ct.1786) (Ellsworth, J.); Mostyn v. Fabrigas, (1774) 98 Eng. Rep. 1021 (K.B.) 1025-26; Casto, Law of Nations, supra note 8, at 503-04 & n. 205. It also would reflect an understanding that a violation of the law of nations could occur within the territorial jurisdiction of a foreign country and be civilly remediable in the United States courts. As early as 1781, Lord Mansfield held in Lindo v. Rodney, 2 Doug. 614 (K.B.), reprinted in Le Caux v. Eden, (1781) 99 Eng. Rep. 375 (K.B.), that “[b]y the law of nations, and treaties, every nation is answerable to the other for all injuries done, by sea or land, or in fresh waters, or in port,” id. at 389 n. 1, and that “every reason which created a Prize Court as to things taken upon the high seas, holds equally when they are thus taken at land,” id., citing treaties as old as 1498, id. at 389, and parliamentary acts from the reign of King George II, id. at 392. Congress adopted this definition of “piracy” in the Act of May 15, 1820, ch. 3, § 3, 3 Stat. 600 (1820). Chancellor Kent, “the great commentator on American law,” Holy Trinity Church v. United States, 143 U.S. 457, 470, 12 S.Ct. 511, 36 L.Ed. 226 (1892), and then “the country’s foremost legal scholar,” Douglas v. Seacoast Prods., Inc., 431 U.S. 265, 278 n. 13, 97 S.Ct. 1740, 52 L.Ed.2d 304 (1977), in “his landmark work,” Sun Oil Co. v. Wortman, 486 U.S. 717, 726, 108 S.Ct. 2117, 100 L.Ed.2d 743 (1988), described both Lindo and the piracy statute as “only declaratory of the law of nations.” 1 James Kent, Commentaries on American Law 189 (New York 8th ed. 1854) (hereinafter “Kent’s Commentaries”). The Crimes Act of 1790 had similarly contemplated violations of the law against piracy committed on land. Id. at 187-89. The dissent, in maintaining that the ATS ought to apply wherever piracy can occur, see Dis. Op. at 78-79, makes no attempt to reconcile its view with early definitions of piracy that are not limited to the high seas. True, the 1790 Act did not provide for primary liability for actions taken on the land of another nation, instead providing punishment as a principal only for crimes of piracy committed “upon the high seas, or in any river, basin or bay, out of the jurisdiction of any particular [U.S.] state,” ch. 9, § 8, 1 Stat. at 113-14; Furlong, 18 U.S. at 200-01. Moreover, amici suggest that the provisions were never invoked by prosecutors in cases involving actions taken within the territory of another nation, Brief of Washington Legal Foundation and Allied Educational Foundation as Amici Curiae in Support of Defendants-Appellees (“Wash. Legal Found. Br.”) 11 n.8, although the facts of Furlong, see supra note 7, weaken this point. Consequently, the historical record, clear on the notion that U.S. courts at the nation’s founding could exercise jurisdiction over at least some international law violations committed beyond our domestic shores and in the territorial waters of another nation, Furlong, 18 U.S. at 200-01, is nonetheless ambiguous regarding whether jurisdiction could be exercised over law of nations violations occurring on the land of another nation. To the extent the historical record is inconclusive, two modern developments convince us that it is entirely appropriate to permit appellants to proceed with their aiding and abetting claims even though much of the conduct relating to the international law violations alleged in their complaint occurred in Indonesia. First, modern ATS litigation has primarily focused on atrocities committed in foreign countries, and Congress in enacting the TVPA expressly endorsed federal courts’ exercise of jurisdiction over such lawsuits. The Report of the Senate Committee on the Judiciary states that the “TVPA would establish an unambiguous basis for a cause of action that has been successfully maintained” in ATS lawsuits such as Filartiga, explaining that in that case “two citizens of Paraguay alleged that a former Paraguayan inspector general of police had tortured and killed a member of their family in Paraguay.” S.Rep. No. 102-249, at 4 (1991). The TVPA thus “enhance[d] the remedy already available under” the ATS by extending that civil remedy also to U.S. citizens who may have been tortured abroad. Id. at 5. Expressing approval for the ATS, the Senate Committee report thus noted that “[consequently, that statute should remain intact.” Id. The Report of the House Committee on the Judiciary is to the same effect. See H.R. Rep. No. 102-367, at 3 (1991). Second, although the United States argued in Sosa that the ATS in no way “applies to alleged torts, such as the one [at issue in Sosa — arbitrary detention], that occur outside of the United States,” Brief for United States at 8, Sosa, 542 U.S. 692 (2004) (No. 03-339); see also id. at 46-50; Reply Brief for United States at 19-20, Sosa, 542 U.S. 692 (2004) (No. 03-339), no Justice indicated agreement with the United States’ position, cf. Sosa, 542 U.S. at 762-63,124 S.Ct. 2739 (Breyer, J., concurring). Given Congress’s ratification of ATS lawsuits involving foreign conduct and the Supreme Court’s failure to disapprove of such lawsuits in Sosa, we conclude that the extraterritoriality canon does not bar appellants from seeking relief based on Exxon’s alleged aiding and abetting of international law violations committed in Indonesia. The arguments of our dissenting colleague offer no basis for a contrary conclusion. First, the dissent notes that injuries of the sort alleged here, by aliens occurring abroad, could be remedied “by foreign sovereigns under their countries’ laws.” Dis. Op. at 77. Perhaps so, but the unchallenged finding by the district court is that the plaintiffs could not litigate their claims in Indonesia, even assuming, as Exxon argued before the district court, that international law required exhaustion of local remedies, because they had demonstrated such efforts would be futile, an exception to prudential exhaustion. Doe I, 393 F.Supp.2d at 25 (citing Hammontree v. NLRB, 925 F.2d 1486, 1517 (D.C.Cir.1991); Rasoulzadeh v. Assoc. Press, 574 F.Supp. 854, 861 (S.D.N.Y.1983), aff'd unthout op. 767 F.2d 908 (2d Cir.1985)). In Rosa, the Supreme Court referenced the exhaustion argument by amicus European Commission but noted that it need not reach the question although stating it “would certainly consider this requirement in an appropriate case.” 542 U.S. at 733 n. 21,124 S.Ct. 2739. Since then the only circuit to address the question concluded that “certain ATS claims are appropriately considered for exhaustion under both domestic prudential standards and core principles of international law,” Sarei v. Rio Tinto, PLC, 550 F.3d 822, 824 (9th Cir.2008) (en banc), noting that “[u]nder international law, ordinarily a state is not required to consider a claim by another state for an injury to its national until that person has exhausted domestic remedies, unless such remedies are clearly sham or inadequate, or their application is unreasonably prolonged,” id. at 829 (quoting Restatement (Third) of Foreign Relations Law of the United States § 713 cmt. f, and citing id. § 703 cmt. d, and Interhandel (Switz. v. U.S.), 1959 I.C.J. 6, 26 (Mar. 29)); the Ninth Circuit also recognized the futility exception applied by the district court here, id. at 830. Because Exxon has not challenged the district court’s finding of futility, this court has no occasion to decide the question. To the extent Exxon suggests subsequent events in Indonesia may have rendered the finding outdated, that issue may be addressed on remand, see infra Part V. C. Second, in deeming “very odd” that the First Congress would be interested in protecting “a Frenchman injured in London,” Dis. Op. at 77, the dissent ignores that the calculus can change where a U.S. citizen is a cause of the harm. E.g., The Apollon, 22 U.S. 362; Furlong, 18 U.S. at 200-01; Rose, 8 U.S. 241. “Congress in prescribing standards of conduct for American citizens may project the impact of its laws beyond the territorial boundaries of the United States,” Steele v. Bulova Watch Co., 344 U.S. 280, 282-83, 73 S.Ct. 252, 97 L.Ed. 319 (1952), especially where a defendant engaged in acts here that “were essential steps in the course of business consummated abroad,” id. at 287, 73 S.Ct. 252. The Supreme Court has not found an extraterritorial bar when a federal statute provided for criminal or civil liability for a scheme devised and executed in the United States intended to inflict harm abroad, e.g., to a Frenchman in London. See Laker Airways Ltd. v. Sabena, Belgian World Airlines, 731 F.2d 909, 921-22 (D.C.Cir.1984); cf. Pasquantino v. United States, 544 U.S. 349, 371-72, 125 S.Ct. 1766, 161 L.Ed.2d 619 (2005). Here, appellants claim that Exxon engaged in acts in the United States that were part and parcel of the harm they suffered. Considering the identity of the person causing harm to the Frenchman in London further illuminates the First Congress’s intent. After all, where the individuals of any state violate this general law [of nations], it is then the interest as well as duty of the government, under which they live, to animadvert upon them with a becoming severity, that the peace of the world may be maintained. For in vain would nations, in their collective capacity, observe these universal rules, if private subjects were at liberty to break them at their own discretion, and involve the two states in a war. It is therefore incumbent upon the nation injured, first, to demand satisfaction and justice to be done on the offender, by the state to which he belongs; and, if that be refused or neglected, the sovereign then avows himself an accomplice or abettor of his subject’s crime, and draws upon his community the calamities of foreign war. 4 Blackstone’s Commentaries *67-68. Blackstone’s representation that a foreign country could deem the United States an “accomplice or abettor,” id. at *68, of a violation of the law of nations if it does not censure a U.S. citizen who has violated that law makes the First Congress’s judgment hardly “odd” at all. B. The rule of statutory construction set forth in Central Bank does not preclude recognition of aiding and abetting liability for claims under the ATS. In Central Bank, the Supreme Court held that although § 10(b) of the Securities and Exchange Act, 15 U.S.C. § 78j, did not prohibit aiding and abetting liability, “the private plaintiff may not bring a 10b-5 suit against a defendant for acts not prohibited by the text of § 10(b),” 511 U.S. at 173, 114 S.Ct. 1439. The Court declined to create a presumption against aiding and abetting liability, but instructed that when Congress enacts a statute, there is no presumption in favor of aiding and abetting liability. Id. at 182, 114 S.Ct. 1439. Our conclusion that there is aiding and abetting liability under the ATS is not based on a presumption in favor of aiding and abetting liability. The ATS provides jurisdiction for the federal courts to hear lawsuits regarding torts “committed in violation of the law of nations.” 28 U.S.C. § 1350. Congress thus directed that the courts derive the rule of law from the law of nations, and that law extends responsibility for conduct violating its norms to aiders and abettors. The “Supreme Court’s instruction in Central Bank that “when Congress enacts a statute under which a person may sue and recover damages from a private defendant for the defendant’s violation of some statutory norm, there is no general presumption that the plaintiff may also sue aiders and abettors,’ is thus inapposite.” Khulumani, 504 F.3d at 282 (Katzmann, J., concurring) (quoting Central Bank, 511 U.S. at 182, 114 S.Ct. 1439) (internal citation omitted); see also id. at 288 n. 5 (Hall, J., concurring); William R. Casto, The New Federal Common Law of Tort Remedies for Violations of International Law, 37 Rutgers L.J. 635, 650 (2006) (hereinafter “Casto, Federal Common Law ”). Ample authority supports the conclusion that the First Congress considered aiding and abetting itself to be a violation of the law of nations. All three branches of government had addressed the subject and were in accord. Congress in 1790 enacted a piracy law providing for aiding and abetting liability. Crimes Act of 1790, § 10, 1 Stat. at 114. President George Washington, in response to the state of hostilities in Europe following the French Revolution, issued the Proclamation of Neutrality in 1793, warning “the citizens of the United States carefully to avoid all acts and proceedings” that would contravene that neutrality and “mak[ing] known that” citizens would render themselves “liable to punishment or forfeiture under the law of nations by committing, aiding, or abetting hostilities against any” power involved in the general conflict “or by carrying to any of them those articles which are deemed contraband by the modern usage of nations.” Proclamation No. 3 (1793), reprinted in 11 Stat. 753 (1859) (emphasis added). So too, the 1795 opinion of Attorney General Bradford stated that civil recovery could be had in federal court against U.S. citizens who “aided and abetted” the French privateer fleet in its plunder of Sierra Leone. 1 U.S. Op. Att’y Gen. at 58; see also Sosa, 542 U.S. at 721, 124 S.Ct. 2739. An early decision of the Supreme Court upheld aiding and abetting liability for the unlawful capture of a neutral ship. See Talbot, 3 U.S. at 167-68; see also Henfield’s Case, 11 F. Cas. 1099. Because aiding and abetting liability implicates the character of the “specific conduct allegedly committed by the defendants sued,” Khulumani, 504 F.3d at 269 (Katzmann, J. concurring), adopted in Presbyterian Church of Sudan, 582 F.3d at 258, the conduct must represent a violation of an international law norm with at least as “definite content and acceptance among civilized nations [as] the historical paradigms familiar” in 1789, Sosa, 542 U.S. at 732, 124 S.Ct. 2739. To the extent the district court in Doe I, 393 F.Supp.2d at 24, concluded that aiding and abetting liability would be an “ ‘innovative interpretation[]’ of the Alien Tort Statute” that could result in “collateral consequences and possible foreign relations repercussions,” the Second Circuit has since held that there can be aiding and abetting liability under the ATS, see Presbyterian Church of Sudan, 582 F.3d at 258-59; Khulumani, 504 F.3d at 260 (per curiam). The Eleventh Circuit has also held that aiding and abetting liability is available under the ATS. See Sinaltrainal v. Coca-Cola Co., 578 F.3d 1252, 1258 n. 5 (11th Cir.2009); Romero v. Drummond Co., Inc., 552 F.3d 1303, 1315 (11th Cir.2008); Aldana v. Del Monte Fresh Produce N.A., 416 F.3d 1242, 1248 (11th Cir.2005). Both courts reached this conclusion upon looking to customary international law, see Presbyterian Church of Sudan, 582 F.3d at 258; Aldana, 416 F.3d at 1247-48, to which we now turn. Decisions of the courts established by the U.N. Security Council, the International Military Tribunal at Nuremberg established in the Agreement for the Prosecution and Punishment of the Major War Criminals of the European Axis, Aug. 8, 1945, U.N.T.S. 280 (hereinafter “London Charter”), and the several Nuremberg tribunals are recognized as an authoritative source of customary international law. See, e.g., Flores v. S. Peru Copper Corp., 414 F.3d 233, 244 n. 18 (2d Cir.2003); United States v. Yousef, 327 F.3d 56, 105 nn.39-40 (2d Cir.2003); cf. Hamdan v. Rumsfeld, 548 U.S. 557, 610 & n. 40, 126 S.Ct. 2749, 165 L.Ed.2d 723 (2006); Princz v. Federal Republic of Germany, 26 F.3d 1166, 1174 (D.C.Cir.1994), cert. denied, 513 U.S. 1121, 115 S.Ct. 923, 130 L.Ed.2d 803 (1995). See generally Theodor Meron, Reflections on the Prosecution of War Crimes by International Tribunals, 100 Am. J. Int’l L. 551, 559 (2006). The General Assembly of the United Nations has unanimously affirmed the principles of international law recognized by the London Charter and the Nuremberg tribunals. See Affirmation of the Principles of International Law Recognized by the Charter of the Nürnberg Tribunal, G.A. Res. 95(1), U.N. Doc. A/236 (Dec. 11, 1946) (“Nuremberg Principles Resolution I”). Exxon does not dispute that the London Charter and the cases prosecuted thereunder constitute sources of customary international law. “[Criminal responsibility of those who aid and abet violations of international law” has been “accepted as one of the core principles of the post-World War II war crimes trials.” Khulumani, 504 F.3d at 273 (Katzmann, J., concurring). The London Charter extended responsibility for crimes to “accomplices participating in the formulation or execution of a common plan or conspiracy to commit” any of the crimes triable by the Tribunal. London Charter art. 6, 82 U.N.T.S. 282. At the direction of the U.N. General Assembly, the International Law Commission (“ILC”) in 1950 formulated “principles recognized in the Charter ... and in the judgment of the Tribunal,” as a codification of certain legal principles applied by the Nuremberg tribunals. See Nuremberg Principles Resolution I; see also Prosecutor v. Akayesu, Case No. ICTR-96-4-T, Trial Chamber Judgement, ¶ 526 (Sept. 2, 1998); Prosecutor v. Milosevic, Case No. IT-02-54, Trial Chamber Decision on Preliminary Motions, ¶¶ 29-30 (Nov. 8, 2001). Principle VII provided that “[c]omplicity in the commission of a crime against peace, a war crime, or a crime against humanity ... is a crime under international law.” ILC, Principles of International Law Recognized in the Charter of the Nürnberg Tribunal and in the Judgment of the Tribunal, G.A.O.R., 5th session, Supp. No. 12, U.N. Doc. A/1316, Principle VII (1950) (“ILC Principles”). Implementing the London Charter, the joint Allied body coordinating the governance of postwar Germany promulgated Control Council Law No. 10 to impose criminal liability on whomever was “an accessory to the commission of any such crime or ordered or abetted the same.” Allied Control Council Law No. 10, art. II, § 2 (Dec. 20, 1945) (“Control Council Law No. 10”), in 1 Enactments and Approved Papers of the Control Council and Coordinating Committee 306 (1945) (“Enactments”); see Khulumani, 504 F.3d at 272 (Katzmann, J., concurring); Flick v. Johnson, 174 F.2d 983, 985-86 (D.C.Cir. 1949). The U.N. Security Council resolutions establishing the International Criminal Tribunal for the Former Yugoslavia (“ICTY”) and the International Criminal Tribunal for Rwanda (“ICTR”) likewise imposed liability on any “person who planned, instigated, ordered, committed or otherwise aided and abetted in the planning, preparation or execution” of a crime. Statute of the International Criminal Tribunal for the Former Yugoslavia, art. 7, U.N. Doc. S/25704 annex (May 3, 1993) (“ICTY Statute”), adopted in S.C. Res. 827, U.N. Doc. S/RES/827 (May 25, 1993); Statute of the International Criminal Tribunal for Rwanda, art. 6, S.C. Res. 955, U.N. Doc. S/RES/955 annex (Nov. 8, 1994) (“ICTR Statute”). The Secretary General of the United Nations explained that “in assigning to the International Tribunal the task of prosecuting persons responsible for serious violations of international humanitarian law, the Security Council would not be creating or purporting to ‘legislate’ that law. Rather, the International Tribunal would have the task of applying existing international humanitarian law.” Report of the Secretary-General Pursuant to Paragraph 2 of Security Council Resolution 808, ¶ 29, U.N. Doc. S/25704 (May 3, 1993) (“Sec’y General ICTY Report”). The ICTY’s jurisdiction was limited to “rules of international humanitarian law which are beyond any doubt part of customary [international] law.” Id. ¶ 34; see Khulumani, 504 F.3d at 275 (Katzmann, J., concurring) (citing Prosecutor v. Furundzija, Case No. IT-95-17/1 Trial Chamber Judgement, ¶¶ 249, 275 (Dec. 10, 1998); Prosecutor v. Tadic, Case No. IT-94-1-T, Trial Chamber Opinion and Judgement, ¶¶ 689-92, 730, 735, 738 (May 7, 1997)). The ICTY emphasized that it was required to determine “the objective basis for such individual responsibility as a matter of customary international law ... since the International Tribunal is only empowered to apply international humanitarian law that is ‘beyond any doubt customary law.’ ” Tadic, Trial Chamber Opinion and Judgement, ¶ 662 (quoting Sec’y General ICTY Report ¶ 34). The ICTR has a similar mandate to that of the ICTY but also encompasses several treaties. See Report of the Secretary-General Pursuant to Paragraph 5 of the Security Council Resolution 955, ¶ 12, U.N. Doc. S/1995/134 (Feb. 13,1995). Federal courts have, in turn, relied on international criminal law norms in estabhshing the content of the law of nations. See, e.g., Khulumani, 504 F.3d at 270 (Katzmann, J., concurring); Kadic, 70 F.3d at 241-43; see also Sosa, 542 U.S. at 762-63, 124 S.Ct. 2739 (Breyer, J., concurring). These authorities and sources confirm that aiding and abetting liability is clearly established in the law of nations and consequently such liability is available under the ATS. C. The question remains what intent must be proved for aiding and abetting liability under the ATS. Appellants suggest that the federal common law standard for aiding and abetting — knowing assistance that has a substantial effect on the commission of the human rights violation — is well established and that the standard under customary international law is essentially the same. Exxon urges the court to follow the Second Circuit in Presbyterian Church of Sudan, 582 F.3d at 259, by requiring proof that the defendant acted with the purpose of committing the alleged human rights violation, maintaining that “[i]f a federal common law aiding and abetting cause of action is to be recognized under the ATS, then Sosa requires that the scope of the federal common law rule derive from international law.” Appellees’ Br. 40. In Sosa, the Supreme Court stated that the ATS’s “jurisdictional grant is best read as having been enacted on the understanding that the common law would provide a cause of action.” 542 U.S. at 724, 124 S.Ct. 2739. From this statement appellants draw the conclusion that federal common law provides the standard for aiding and abetting liability. Judge Edwards similarly observed in Tel-Oren, 726 F.2d at 777-78, that “the law of nations never has been perceived to create or define the civil actions to be made available by each member of the community of nations; by consensus, the states leave that determination to their respective municipal laws.” Appellants also cite the United States’ amicus brief in the Second Circuit urging that the “validity of a federal-common-law claim under Sosa should generally be treated as a merits question, with the ATS conferring subject-matter jurisdiction so long as the allegations of a violation of customary international law are not plainly insubstantial.” Brief for the United States as Amicus Curiae at 20, Abdullahi v. Pfizer, Inc., 562 F.3d 163 (2d Cir.2009). Appellants suggest that “[t]he application of domestic common law standards is essential because international law does not ordinarily provide for the means of its own enforcement in domestic courts,” Appellants’ Br. 33, and in their view, the Supreme Court in Sosa, 542 U.S. at 731, 124 S.Ct. 2739, “endorsed Judge Edwards’ view that domestic rules govern the litigation of ATS claims in U.S. courts,” Appellants’ Br. 33-34. The history of the ATS examined by the Supreme Court in Sosa, 542 U.S. at 731, 124 S.Ct. 2739, indicated the First Congress’s understanding that federal common law would supply the rules in ATS cases. Amici law professors in Sosa noted that when the ATS was enacted there was no clear distinction between common law and customary international law. See Brief of Professors of Federal Jurisdiction and Legal History as Amici Curiae in Support of Respondents, Sosa v. Alvarez-Machain, 542 U.S. 692 (2004) (No. 03-339), reprinted in 28 Hastings Int’l & Comp. L.Rev. 99,109 (2004) (“Sosa Legal History Amicus Br.”). Courts routinely treated causes of action arising under international law as they did other common law torts — by applying general common law principles. See, e.g., Talbot, 3 U.S. (3 Dall.) at 155-58 (Paterson, J.); id. at 161 (Iredell, J.); id. at 169 (Rutledge, C. J.); United States v. Benner, 24 F. Cas. 1084, 1087 (C.C.E.D.Pa.1830) (No. 14,568). Appellants maintain that the application of common law rules to ATS cases is consistent with the way in which federal courts implement other federal statutes. See, e.g., United States v. Kimbell Foods, Inc., 440 U.S. 715, 727, 99 S.Ct. 1448, 59 L.Ed.2d 711 (1979); see also Tex. Indus., Inc. v. Radcliff Materials, Inc., 451 U.S. 630, 641, 101 S.Ct. 2061, 68 L.Ed.2d 500 (1981). The Eleventh Circuit has adopted this approach, holding that a knowledge standard applies because that is the standard under federal common law. See Cabello v. Fernandez-Larios, 402 F.3d 1148, 1157-60 (11th Cir.2005); cf. Doe v. Islamic Salvation Front, 257 F.Supp.2d 115, 120 n. 12 (D.D.C.2003). That a particular cause of action cognizable under the ATS is to be recognized as a federal common law claim, however, does not identify the source of law to which the court must look for a standard. The Supreme Court in Sosa mandated that courts recognize only “a narrow set of common law actions derived from the law of nations.” 542 U.S. at 721, 124 S.Ct. 2739. In so doing, a court must identify a norm for conduct of no less “definite content and acceptance among civilized nations than the historical paradigms familiar when § 1350 was enacted,” id. at 732, 124 S.Ct. 2739, to which the international community expresses approbation or disapprobation. Aiding and abetting liability, while supplemental to some other alleged tort liability, is based on conduct distinct from the conduct of the principal actor. Consistent with Sosa, the question is whether the international community would express definite disapprobation toward aiding and abetting conduct only when based on a particular standard. The court therefore looks to customary international law to determine the standard for assessing aiding and abetting liability, much as we did in addressing availability of aiding and abetting liability itself. Important sources are the international tribunals mandated by their charter to apply only customary international law. Two such tribunals, the International Criminal Tribunals for the Former Yugoslavia and Rwanda, are considered authoritative sources of customary international law. See, e.g., Hamdan, 548 U.S. at 611 n. 40, 126 S.Ct. 2749; Abagninin v. AMVAC Chem. Corp., 545 F.3d 733, 739 (9th Cir.2008); Ford ex rel. Estate of Ford v. Garcia, 289 F.3d 1283, 1293 (11th Cir.2002). They have declared the knowledge standard suffices under customary international law. The ICTY, in addressing whether the accomplice must “share the mens rea of the principal or whether mere knowledge” will suffice, concluded that “the latter will suffice.” Furundzija, Trial Chamber Judgement, ¶ 236. It is not necessary that the aider and abettor “shares the mens rea of the perpetrator, in the sense of positive intention to commit the crime,” provided he “ha[s] knowledge that his actions will assist the perpetrator in the commission of the crime.” Id. ¶ 245. The Trial Chamber’s judgment states: [T]he actus reus [of aiding and abetting] consists of practical assistance, encouragement, or moral support which has a substantial effect on the perpetration of the crime. The mens rea required is the knowledge that these acts assist the commission of the offense. Id. ¶ 249; see also id. ¶¶ 238-40, 245-46 (citing inter alia, In re Tesch, 1 Law Reports of Trials of War Criminals 93); Prosecutor v. Krstic, Case No. IT -98-33-A, Appeals Judgement, ¶¶ 139-41 (Apr. 19, 2004); Prosecutor v. Delalic, Case No. IT-96-21-1, Trial Chamber Judgement, ¶¶ 325-29 (Nov. 16, 1998); Tadic, Trial Chamber Judgement, ¶¶ 674, 692. The ICTR is in agreement. See Prosecutor v. Ntakirutimana, Case No. ICTR-96-13-I, Appeals Judgement, ¶ 501 (Dec., 13, 2004); Prosecutor v. Musema, Case No. ICTR96-13-1, Trial Chamber Judgement, ¶¶ 180-82 (Jan. 27, 2000). The parties do not suggest that the approach of the ICTY and the ICTR is inconsistent with the federal standard for aiding and abetting liability. In Halberstam v. Welch, 705 F.2d 472 (D.C.Cir.1983), which the Supreme Court described as “a comprehensive opinion on the subject [of aiding and abetting],” Central Bank, 511 U.S. at 181, 114 S.Ct. 1439, this court defined the scope of aiding and abetting for tort liability in the civil context as follows: (1) the party whom the defendant aids must perform a wrongful act that causes an injury; (2) the defendant must be generally aware of his role as part of an overall illegal or tortious activity at the time that he provides the assistance; (3) the defendant must knowingly and substantially assist th