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The Crime of Aggression: The United States Perspective

  • Harold Hongju Koh (a1) (a2) and Todd F. Buchwald (a3) (a2)

At the 2010 Review Conference in Kampala, the states parties to the Rome Statute of the International Criminal Court (ICC) decided to adopt seven amendments to the Rome Statute that contemplate the possibility of the Court exercising jurisdiction over the crime of aggression subject to certain conditions. One condition was that the exercise of jurisdiction would be “subject to a decision to be taken after 1 January 2017 by the same majority of States Parties as is required for the adoption of an amendment to the Statute,” and another was that such jurisdiction could be exercised “only with respect to crimes of aggression committed one year after the ratification or acceptance of the amendments by thirty States Parties.” As these dates approach, we—two lawyers who represented the United States at the Kampala conference and who worked many hours on the United States’ reengagement with the ICC during the Obama administration—thought it an appropriate moment to take stock of where we are, how we got here, and where we might or should be headed with respect to the crime of aggression.

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1 Rome Statute of the International Criminal Court, July 17, 1998, 2187 UNTS 90 [hereinafter Rome Statute]; International Criminal Court, Assembly of States Parties, Review Conference, The Crime of Aggression, ICC Res. RC/Res.6, Arts. 15 bis (2–3), 15 ter (2–3) (June 11, 2010). The resolution on the crime of aggression, as well as the other resolutions from the Kampala conference, is contained in the Review Conference’s Official Records, ICC Doc. RC/11 (2010). Part I includes the proceedings, and Part II the resolutions, declarations, and various annexes. The Web page for the Assembly of States Parties,, provides access to all official records, general debates, and other records and documentation. The Rome Statute itself and other legal texts are available at

2 For a recent comprehensive review, see Koh, Harold Hongju, International Criminal Justice 5.0, 38 Yale J. Int’l L. 525 (2013).

3 See Press Release, United States Mission to the United Nations, Statement by Jamison S. Borek, Deputy Legal Adviser, United States Department of State, at the 50th Session of the United Nations General Assembly, Sixth Committee (Nov. 1, 1995) (regarding the establishment of an international criminal court), at

4 Id.

5 See Rome Statute, supra note 1, Art. 5(2) (“The Court shall exercise jurisdiction over the crime of aggression once a provision is adopted in accordance with articles 121 and 123 defining the crime and setting out the conditions under which the Court shall exercise jurisdiction with respect to this crime.”); id., Art. 123 (Review Conference to be convened seven years after entry into force of the treaty).

6 Is a U.N. International Criminal Court in the U.S. National Interest?, Hearing Before the Subcomm. on Int’l Operations of the S. Comm. on Foreign Relations, 105th Cong. 10–47 (July 23, 1998) (statement of David J. Scheffer, ambassador-at-large for war crimes issues); UN GAOR, 53d Sess., 9th mtg., para. 58, UN Doc A/C.6/53/SR.9 (Nov.4, 1998) (remarks of David J. Scheffer before the 6th Committee of the General Assembly on Oct. 21, 1998).

7 William J. Clinton, Statement on the Rome Treaty on the International Criminal Court, 3 Pub. Papers 2816 (Dec. 31, 2000).

8 Press Release, Senate Foreign Relations Committee Chairman Jesse Helms, Helms on Clinton ICC Signature: “This Decision Will Not Stand” (Dec. 31, 2000), at

9 International Criminal Court: Letter to UN Secretary General Kofi Annan (May 6, 2002), at http://2001–

10 Many of the Court’s supporters particularly criticized the effort by the United States to conclude bilateral “Article 98 agreements,” including the enactment into U.S. law of the American Servicemembers’ Protection Act. See, e.g., Human Rights Watch, United States Efforts to Undermine the International Criminal Court (Oct. 3, 2002), at (stating that “[s]uch impunity agreements violate the Rome Statute and should be opposed”). Many also criticized the U.S. insistence on including language in Security Council resolutions to provide protections that it considered necessary for personnel from non–Rome Statute parties against the Court’s jurisdiction,see SC Res. 1422 (July 12, 2002), 1492 (July 28, 2003), U.S. efforts to prevent references to the ICC in the resolutions adopted by United Nations and other bodies, and the U.S. decisions not to join consensus on the annual UN General Assembly resolutions regarding the Court or to participate in the meetings of the Assembly of States Parties. See, e.g., UN GAOR, 57th Sess., 52d plen. mtg. at 10, UN Doc. A/57/PV.52 (Nov. 19, 2002) (Rafael Martinez for the United States).

11 Most notably, the Bush administration instructed the U.S. Mission in New York to abstain on Security Council Resolution 1593 (Mar. 31, 2005), so as to allow the Council to refer the situation in Darfur to the Court’s prosecutor in March 2005. Soon thereafter, senior U.S. officials made statements that “not only do we not oppose the ICC’s investigation and prosecutions in Sudan but we support its investigation and prosecution of those atrocities.” George Gedda,U.S. Sees ICC in More Benevolent Light, Wash. Post, Dec. 29, 2006 (statement of John B.Bellinger III), at There were numerous other statements to the same effect. See, e.g., U.S. Department of State, Remarks at the Brookings Institution on the Situation in Darfur (Apr. 13, 2006) (statement of Deputy Secretary of State Robert Zoellick), at http://2001–; ‘Meet the Press’ transcript for Dec. 21, 2008, NBC (Dec. 21, 2008) (interview with U.S. Secretary of State Condoleezza Rice), at; see also Wasil Ali, ICC: ‘No Sudanese Official Immune from Prosecution,’ Sudan Trib. (Dec. 18, 2006) (remarks of the chief ICC prosecutor, Luis Moreno Ocampo, noting shift in U.S. policy and “mounting signs of the U.S. warming up to the ICC”), at Toward the end of the Bush administration, Legal Adviser John Bellinger gave a speech acknowledging the valuable role that the Court can play and making clear that the United States does not seek to prevent other countries from deciding to become parties to the Rome Statute. John B. Bellinger III, Speech Before the Council on Foreign Relations (Apr. 25, 2008), at

12 Nomination of Hillary R. Clinton to Be Secretary of State, Hearing Before the Senate Comm. on Foreign Relations, 111th Cong. 135 (2009), at

13 See Koh, supra note 2, at 534 (“many in our country still have fundamental concerns about the Rome Statute that have prevented us from becoming a party”).

14 See Nomination of Hillary R. Clinton to Be Secretary of State, supra note 12, at 131.

15 On an official level, the negotiations took place on a”general understanding that ‘nothing is agreed until everything is agreed.’” Report of the Special Working Group on the Crime of Aggression, para. 4, ICC Doc. ICC-ASP/7/SWGCA/2 (Feb. 20, 2009). At an informal level, however, many participants proceeded on the basis that the crime-of-aggression package had consensus support subject only to resolution of the elements that had been included in brackets. See Barriga, Stefan,Against the Odds: Results of the Special Working Group on the Crime of Aggression, in International Criminal Justice: Law and Practice from the Rome Statute to its Review 621, 623 (Bellelli, Roberto ed., 2010 ) (“On the face of it, only two issues remain to be resolved. The first is whether the provisions on aggression should only be binding upon those States Parties that have accepted the amendment (Article 121(5) [of the Rome Statute]), or whether the amendment would enter into force for all States Parties once ratified by seven-eighths of them (Article 121(4) [of the Rome Statute]). The second is the question of the role of the Security Council, and implicitly the role of the Permanent Members of the Council.”).

16 Vijay Padmanabhan, Council on Foreign Relations, Special Report No. 55: From Rome to Kampala: The U.S. Approach to the 2010 International Criminal Court Review Conference 4 (2010).

17 Rapp said:

Having been absent from previous rounds of these meetings, much of what we will do here is listen and learn. Our presence at this meeting, and the contacts that our delegates will seek with as many of you as possible, reflects our interest in gaining a better understanding of the issues being considered here and the workings of the Court.

Stephen J. Rapp, U.S. Ambassador at Large for War Crimes Issues, Speech to Assembly of States Parties (Nov. 19, 2009),at

18 Id.

19 See supra note 15.

20 Under the package that had been produced by the Special Working Group, “trigger” mechanisms included those that exist under Article 13 of the Rome Statute for state referral and proprio motu situations, whereas the question of “filters” would arise at a later stage, after the prosecutor had concluded that there was a reasonable basis to proceed with an investigation. See Barriga, supra note 15, at 632.

21 See Remarks by Mathias, D. Stephen, in The Definition of Aggression and the ICC, 96 Asil Proc. 181, 182 (2002).

22 See id. at 182 (noting that Article 23, paragraph 2, of the draft statute adopted by the International Law Commission provided that no complaint related to an act of aggression could be brought before the Court “unless the Security Council has first determined that a State has committed the act of aggression which is the subject of the complaint”) (emphasis added); International Law Commission, Reportonthe Work of Its Forty-Sixth Session, UN GAOR, 49th Sess., Supp. No. 10, at 84, 86, UN Doc. A/49/10 (1994) (“Any criminal responsibility of an indi vidual for an act or crime of aggression necessarily presupposes that a State had been held to have committed aggression, and such a finding would be for the Security Council acting in accordance with Chapter VII of the Charter... to make.”) (emphasis added).

23 See, for example, the nongovernmental organization of the same name, at

24 See, e.g., Peace and Justice in Post-conflict Societies—the UN Position, 3 Int’l Org. L. Rev. 395, 395 (2006) (legal opinions of the Office of Legal Affairs of the United Nations) (“The UN does not recognize any amnesty for genocide, crimes against humanity, war crimes and other serious violations of international humanitarian law.”).

25 ICC Doc. ICC-ASP/7/SWGCA/2, supra note 15.

26 Definition of Aggression, GA Res. 3314 (XXIX), annex (Dec. 14, 1974).

27 Article 1 of the Resolution 3314 definition states: “Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations, as set out in this Definition.” Id., Art. 1 (emphasis added).

28 Definition of Aggression, supra note 26, para. 3 (emphasis added).

29 Specifically, the first sentence of Article 8 bis (2) omits the key phrase from Article 1—”as set out in this Definition”—a phrase that, by incorporating the seven other articles that contained additional elements modifying what the meaning of the sentence would otherwise be, was clearly intended to establish that not all violations of Article 2(4) constitute acts of aggression.

30 Consolidated Text of the Reports of the Contact Groups and of the Drafting Group, in Report of the Special Committee on the Question of Defining Aggression, Annex II, App. A, UN Doc. A/9019, A, at 16 (1973). The draft of the so-called Six Powers (Australia, Canada, Italy, Japan, United Kingdom, and United States) that was considered in the run-up to the adoption of Resolution 3314 included an illustrative list of purposes that were of the type that might be consistent with a conclusion that aparticular use of force constituted aggression. In particular, uses of force might constitute acts of aggression if they were undertaken “[i]n order to: (1) Diminish the territory or alter the boundaries of another State; (2) Alter internationally agreed lines of demarcation; (3) Disrupt or interfere with the conduct of affairs of another State; (4) Secure changes in the government of another State; or (5) Inflict harm or obtain concessions of any sort.” The precise list of purposes in the Six Powers draft is less important than the fact that it was clearly contemplated that purpose should be an element to be considered in determining whether an act of aggression had occurred. Draft Proposals Before the Special Committee, in Report of the Special Committee on the Question of Defining Aggression, supra, Annex I, at 11–12.

31 See Report of the Special Committee on the Question of Defining Aggression, UN GAOR, 29th Sess., Supp. No. 19, UN Doc. A/9619, at 23 (1974).

32 Id. at 36; see also Paulus, Andreas L., Peace Through Justice? The Future of the Crime of Aggression in a Time of Crisis, 50 Wayne L. Rev. 1, 27 (2004) (discussing litigation under German domestic law distinguishing aggression from “a mere violation of the prohibition on the use of force” and noting that the absence of a specific intent “to disturb the peaceful coexistence of peoples” and the “benign motives of NATO action” rendered the German government non-prosecutable).

33 The precise language of Article 2 of the Resolution 3314 definition, to which the provisions of Article 3 are subject, is as follows:

The first use of armed force by a State in contravention of the Charter shall constitute prima facie evidence of an act of aggression although the Security Council may, in conformity with the Charter, conclude that a determination that an act of aggression has been committed would not be justified in the light of other relevant circumstances, including the fact that the acts concerned or their consequences are not of sufficient gravity.

The italicized language at the end of the sentence (our emphasis) made clear that it would not be justified to conclude that any of the enumerated acts would be an act of aggression absent the requisite gravity or “other relevant circumstances.”

34 This last approach—that the two sentences are considered coterminous—was perhaps suggested by the draft Elements of Crimes, the third element of which was as follows: “The act of aggression—the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, orinany other manner inconsistent with the Charter of the United Nations—was committed.” This last approach also appears consistent with the views expressed by delegations during the negotiations that were summarized as follows in the Special Working Group’s report of its June 2008 meeting:

Those delegations that supported the drafting of paragraph 2 expressed their understanding that the list of crimes was, at least to a certain extent, open. Acts other than those listed could thus be considered acts of aggression, provided that they were of a similar nature and gravity to those listed and would satisfy the general criteria contained in the chapeau of paragraph 2. In this connection, it was stressed that the right balance had been struck in the Chairman’s paper by including a generic definition in the chapeau of paragraph 2, along with the non-exhaustive listing of acts of aggression.

Report of the Special Working Group on the Crime of Aggression, para. 34, in ICC Doc. ICC-ASP/6/20/Add.l, Annex II (2008).

35 See Report of the Special Working Group on the Crime of Aggression, ICC Doc.ICC-ASP/7/SWGCA/2,supra note 15, para. 14 (stating that the space between the two sentences was deleted to “enhance clarity”).

36 See GA Res. 3314 (XXIX), supra note 26, annex, Art. 5(2) (“A war of aggression is a crime against international peace.”).

37 Charter of the International Military Tribunal, Art. 6, Aug. 8, 1945, 59 Stat. 1544, 8 UNTS 279 (Nuremberg Charter) (defining “crimes against peace” as “namely, planning, preparation, initiation or waging of a war of aggression, or a war in violation of international treaties, agreements or assurances, or participation in a common plan or conspiracy”); see also Charter of the International Military Tribunal for the Far East, Art. 5, Jan. 19, 1946, TIAS No. 1589 (Tokyo Tribunal); Declaration on Principles of International Law Concerning Friendly Relations and Co-operation Among States in Accordance with the Charter of the United Nations, GA Res. 2625, pmbl. (Oct. 24, 1970) (specifying that it is a “war of aggression [that] constitutes a crime against the peace” (emphasis added)).

38 See, e.g., Report of the Special Committee on the Question of Defining Aggression, supra note 31, at 16 (Japan affirming “that an act of aggression which was not part of a war of aggression gave rise only to State responsibility”).

39 See Proposal Submitted by Germany: The Crime of Aggression, paras. 20–21, PCNICC/2000/WGCA/DP.4 (Nov. 13, 2000).

40 See The Random House Dictionary of the English Language, College Edition 813 (New York, 1980). The entry goes on to give “clear,” “distinct,” and “unmistakable” as synonyms. In a similar vein that appears to focus on considerations related to clarity, Article 46(2) of the Vienna Convention on the Law of Treaties, May 23, 1969, 1155 UNTS 331, provides that a state may not invoke the fact that its consent to be bound by a treaty has been expressed in violation of its internal law regarding competence to conclude treaties unless that violation was, inter alia, manifest; and then proceeds to provide that “[a] violation is manifest if it would be objectively evident to any State conducting itself in the matter in accordance with normal practice and good faith.”

41 Rome Statute, supra note 1, Art. 5(1).

42 Id., Art. 17(1)(d).

43 Id., Art. 53(1)(c).

44 Judicial Decisions, International Military Tribunal (Nuremberg), Judgment and Sentences, 41 AJIL 172, 186 (1947) (emphasis added).

45 We have heard anecdotal evidence that such a chilling effect has already hindered international efforts to stop the ongoing slaughter in Syria. Such a chilling effect could well encourage international actors to engage in behavior against which force would otherwise appropriately be used, and thereby have the perverse effect of undermining rather than strengthening international peace and security. Cf. Taft, William H., Self-Defense and the Oil Platforms Decision, 29 Yale J. Int’l L. 291, 299–300 (2004).

46 Another Understanding related to the definition of “crime of aggression” as opposed to “act of aggression.” Specifically, paragraph 7 provided:

It is understood that in establishing whether an act of aggression constitutes a manifest violation of the Charter of the United Nations, the three components of character, gravity and scale must be sufficient to justify a “manifest” determination. No one component can be significant enough to satisfy the manifest standard by itself.

This Understanding was designed to underscore that the three factors in determining whether an act of aggression is a manifest violation of the UN Charter—character, gravity, and scale—must be read conjunctively; that is, the use of the word “and” in Article 8 bis (1) is based on an understanding that any one element could not be sufficient for this purpose and that all must be present. This does not directly address, of course, the more fundamental concerns, as described above, about the way that the Court may ultimately interpret the word “manifest.” The Kampala participants declined to adopt proposed language that more straightforwardly stated that “it is only a war of aggression that is a crime against international peace.” Still, it remained our view that it is on that basis that the Court would need to proceed if a crime of aggression case was ever prosecuted—a point made by Resolution 3314 itself.

47 Non-paper by the United States,reproduced in The Travaux Préparatoires of the Crime of Aggresion 751–52 (Stefan Barriga & Claus Kress eds., 2012); see also Statement at the Review Conference of the International Criminal Court (June 4, 2010), at (statement by Legal Adviser Harold Hongju Koh, U.S. Department of State, arguing for Understandings that would “make clear that those who undertake efforts to prevent war crimes, crimes against humanity or genocide—the very crimes that the Rome Statute is designed to deter—do not commit ‘manifest’ violations of the UN Charter within the meaning of Article 8 bis. Regardless of how states may view the legality of such efforts, those who plan them are not committing the ‘crime of aggression’ and should not run the risk of prosecution.”).

48 See, e.g., Heller, Kevin Jon, The Uncertain Legal Status of the Aggression Understandings, 10 J. Int’l Crim. Just. 229 (2012) (arguing that the Court would have the right to ignore the Understandings unless they are adopted by all of the states parties to the Rome Statute).

49 See, e.g., Report of the Working Group on the Review Conference, ICC Doc. ICC-ASP/8/20/Add.1, Annex II (2010).

50 Statement at the Review Conference of the International Criminal Court, supra note 47.

51 See, e.g., Williams, Sharon A., Article 12, in Commentary on the Rome Statute of the International Criminal Court 329, 340 (Triffterer, Otto ed., 1999) (“When an alien commits a crime... on the ter ritory of another State, a prosecution in the latter State is not dependent on the State of nationality being a Party to the pertinent treaty or otherwise consenting.... There is no rule of international law prohibiting the territorial State from voluntarily delegating to the ICC its sovereign ability to prosecute.” (footnotes omitted)).

52 Article 8 of the draft code provided:

Without prejudice to the jurisdiction of an international criminal court, each State Party shall take such measures as may be necessary to establish its jurisdiction over [genocide, crimes against humanity, crimes against UN personnel, and war crimes], irrespective of where or by whom those crimes were committed. Jurisdiction over the crime set out in article 16[aggression] shall rest with an international criminal court. However, a State referred to in article 16 is not precluded from trying its nationals for the crime set out in that article.

Code of Crimes Against the Peace and Security of Mankind, in Report of the International Law Commission on the Work of Its Forty-Eighth Session, UN GAOR, 51st Sess., Supp. No. 10, UN Doc. A/51/10, at 27.

53 Id., Art. 8, cmt. 14 (emphasis (of full sentence) added).

54 Id., cmt. 15 (emphasis added).

55 See Coracini, Astrid R., Evaluating Domestic Legislation on the Customary Crime of Aggression Under the Rome Statute’s Complementarity Regime, in The Emerging Practice of the International Criminal Court 733 (Stahn, Carsten & Sluiter, Goran eds., 2009).

56 It is also noteworthy that the definitions in the relevant national legislation do not necessarily match the definitions adopted by the Special Working Group. See Van Schaack, Beth, Par in Parem Imperium Non Habet, 10 J. Int’l Crim. Just. 133, 138–141, 152 (2012) (“Legislators incorporating the crime into national penal codes may drop or change definitional elements of the crime, enabling more expansive prosecutions than have been deemed acceptable by the [Assembly of States Parties].”).

57 See Dapo Akande, Prosecuting Aggression: The Consent Problem and the Role of the Security Council, 31–32 (Oxford Inst. for Ethics, Law & Armed Conflict, Working Paper, 2010), at (footnotes omitted). Akande states:

Even if one were to take the view that the Nuremburg Tribunal was nota national or quasi- national tribunal but instead was a tribunal operating exclusively on the plane of international law, there would still be the question whether it operated in the absence of the consent of the State whose acts it judged when it considered the waging of aggressive war. At the relevant time Germany had surrendered to the Allied powers and had been occupied by those countries. Strictly speaking, Germany had lost its sovereignty, in the sense of its independence, as a matter of international law, and the Allied powers had assumed governmental control over it. In fact, and in law, they had joint supreme authority or sovereignty over Germany. This means that Allied powers possessed the right and power to exercise for Germany all acts and all competences which the German government could have exercised and possessed. From this perspective, the establishment of the Nuremberg Tribunal cannot be regarded as departing from the principle of consent or indeed of establishing a new principle whereby an international tribunal can be established which pronounces, as an essential aspect of its jurisdiction, on the obligations and responsibilities of a State, without the consent of that State. Clearly, the Allied powers, which were the governing authorities of Germany, consented to the exercise of jurisdiction over German acts by the Nuremburg Tribunal, for they established it.

See also the Berlin Declaration of June 5, 1945, 60 Stat. 1649, 1650 (“The Governments of the United States of America, the Union of Soviet Socialist Republics and the United Kingdom, and the Provisional Government of the French Republic hereby assume supreme authority with respect to Germany, including all powers possessed by the German Government, the High Command and any state, municipal, or local government authority.”). The situation was different with respect to Japan, the government of which continued to exist after World War II and consented to the establishment of the Tokyo Tribunal. See Boister, Neil, The Tokyo Trial, in Routledge Handbook of International Criminal Law 18 (Schabas, William A. & Bernaz, Nadia eds., 2011).

58 See Barriga, Stefan & Grover, Leena, A Historic Breakthrough on the Crime of Aggression, 105 AJIL 517, 532 n.38 (2011) (noting agreement that Kampala adopted a consent-based regime and that differences of view involve only how that consent needs to be expressed).

59 It was with this possibility in mind that paragraph 5 was included in the Understandings attached as Annex III to the resolution that the states parties adopted in Kampala. Paragraph 5 provided: “It is understood that the amendments shall not be interpreted as creating the right or obligation to exercise domestic jurisdiction with respect to an act of aggression committed by another State.” While on its face this Understanding does not preclude arguments that a state might otherwise have authority to prosecute the crime of aggression (and surely nothing in inter national law would prevent it from doing so with respect to its own leaders), it does separate the crime of aggression from the atrocity crimes in the Rome Statute—genocide, crimes against humanity, and war crimes—with respect to which many in the international community look to the Rome Statute as verifying that it is appropriate and desirable for states to prosecute such cases.

60 For a thorough discussion of the many still-unaddressed issues involved in reconciling the principle of complementarity and the crime of aggression, see generally Julie Veroff, Note, Reconciling the Crime of Aggression and Complementarity: Unaddressed Tensions and a Way Forward, 125 Yale. L.J. (forthcoming).

61 Article 5(2) went on to provide that “[s]uch a provision shall be consistent with the relevant provisions of the Charter of the United Nations.”

62 See, e.g., Report of the Preparatory Committee on the Establishment of an International Criminal Court, UN Doc. A/CONF.183/2/Add.1 (Apr. 14, 1998).

63 See Rome Statute of the International Criminal Court, Art.121(5), July17,1998, UN Doc.A/CONF.183/9*, 37 ILM 999 (1998). An online copy is available at

64 See Vienna Convention on the Law of Treaties, supra note 40.

65 Draft Articles on the Law of Treaties with Commentaries, [1966] 2 Y.B. Int’l L. Comm’n 187, 272.

66 The UN secretary-general, for whom the head of the Office of Legal Affairs serves as legal counsel, had been designated as the depositary for the treaty. Rome Statute, supra note 1, Art. 121(5). See also Vienna Convention on the Law of Treaties, supra note 40, Art. 79 (describing role of depositary in the correction of errors in the texts of treaties).

67 Letter from Philippe Kirsch to Hans Corell, UN Under-Secretary-General and Legal Counsel (Sept. 3, 1998), partially reprinted in Pellet, Allain, Entry into Force and Amendment of the Statute, 1 The Rome Statute of the International Criminal Court: A Commentary (Cassese, Antonio, Gaeta, Paolo & Jones, John R. W. D. eds., 2002), at 145, 181.

68 See Zimmerman, Andreas, Amending the Amendment Provisions of the Rome Statute: The Kampala Compromise on the Crime of Aggression and the Law of Treaties, 10 J. Int’l Crim. Just. 209, 218 (2012) (“[W]hile contracting parties were generally willing to automatically submit to the Court’s jurisdiction by way of their ratification of the Statute (which, in itself, constituted a major step forward as compared to, for instance, the jurisdiction of other international courts and tribunals, such as the International Court of Justice), they were only willing to do so to the extent they had accepted the substantive law governing the exercise by the Court of its jurisdiction. Otherwise, they wanted to shield themselves, as well as their nationals, from the exercise of jurisdiction by the Court on the basis of any amendments they could not foresee and, ultimately, could not prevent from entering into force.”).

69 See Draft Amendments to the Rome Statute of the International Criminal Court on the Crime of Aggression, para. 1 (Feb. 2009), reprinted in The Princeton Process on the Crime of Aggression: Materials of the Special Working Group on the Crime of Aggression 2003 –2009, at 60–62(Stefan Barriga, Wolf-gang Danspeckgruber & Christian Wenaweser eds., 2009).

70 At the same time, there was a general view that Articles 121(4) and 121(5) were alternatives; that is, one or the other, but not both, could apply at the same time. Barriga, supra note 15, at 635 (footnotes omitted) (“So far, any attempts to consider the two provisions as complementary rather than mutually exclusive have been rejected, and it is thus likely that in the final decision on the matter, the Review Conference will simply have to choose one or the other option.”). Yet this conclusion, too, was not completely obvious.

71 See, e.g., Article 15 bis (1) (“The Court may exercise jurisdiction over the crime of aggression in accordance with article 13, paragraphs (a) and (c), subject to the provisions of this article.”). Both Articles 15 bis and 15 ter modify the Court’s ability to exercise jurisdiction over the crime of aggression under Article 13, with the consequence that the otherwise applicable rules under Article 13 are made subject to the provisions of these two new articles. Thus, the rules would limit the Court’s jurisdiction in state referral and proprio motu cases, meaning that the Court may exercise jurisdiction only after thirty states ratified and only after a decision, referred to in the amendments, taken by the states parties after January 1, 2017.

72 Specifically, the pattern here is the same as with the Statute of the International Court of Justice, under which all parties to the ICJ Statute have agreed that the Court will have compulsory jurisdiction only over those states that make a declaration under Article 36.

73 ICC Res. RC/Res.6, supra note 1.

74 Vienna Convention on the Law of Treaties, supra note 40, Art. 31(1).

75 Id., Art. 32.

76 See, e.g., Wenaweser, Christian, Reaching the Kampala Compromise on Aggression: The Chair’s Perspective, 23 Leiden J. Int’l L. 883, 887 (2010) (highlighting importance in the amendments of “the wholesale exemption for non–states parties”); Barriga, Stefan, Exercise of Jurisdiction and Entry into Force of the Amendments on the Crime of Aggression, in From Rome to Kampala: The First 2 Amendments to the Rome Statute 31, 41 (Dive, Gérad, Goes, Benjamin & Vandermeersch, Damien eds., 2012) (“article 15 bis (5) is very unambiguous” as to whether the Court lacks jurisdiction if a non–state party is the alleged aggressor); Blokker, Niels & Kress, Claus, A Consensus Agreement on the Crime of Aggression: Impressions from Kampala, 23 Leiden J. Int’l L. 889, 893 (2010) (“the ICC will be precluded from exercising jurisdiction over the crime of aggression with respect to acts of aggression by and against non–state parties”); Kress, Claus & von Holtzendorff, Leonie, The Kampala Compromise on the Crime of Aggression, 8 J. Int’l Crim. Just. 1179, 1212–13 (2010) (“the Court will not be able to exercise its jurisdiction over an alleged crime of aggression arising from an act of aggression of a non–State Party”); Handbook: Ratification and Implementation of the Kampala Amendments to the Rome Statute of the Icc: Crime of Aggression, War Crimes 10 (Liechtenstein Institute on Self-Determination, Woodrow Wilson Schoolof Public and International Affairs, Princeton University, n.d.) (Accordingto Article 15 bis (5), “Non–States Parties are thus excluded both as potential aggressor and victim States.”).

77 See Barriga, supra note 76, at 38–39 (“Notably, article 5(2) does not state that the conditions for the exercise of jurisdiction over the crime of aggression shall include the limits of article 121(5), second sentence. Instead, it leaves it up to the provision to be adopted by States Parties to set out the conditions for the exercise of jurisdiction, and in doing so confers broad powers upon States Parties to find an aggression-specific solution for this issue.”); Wenaweser, supra note 76, at 885–86 (jurisdictional regime under the amendments is “on the basis of the acceptance already given by states parties”); Kress & von Holtzendorff, supra note 76, at 1215 (“Article 5(2) of the ICC Statute must be taken to entitle States Parties to devise the sui generis –regime which has made its way into draft Article 15 bis (4) of the ICC Statute” even if the legal foundation “is perhaps not rock solid.”).

The proponents of the Article 5(2)/Article 12 theory argue that the language of Article 15 bis (4)—providing that the Court may exercise jurisdiction over the crime of aggression “in accordance with article 12”—requires that either the alleged aggressor or the alleged victim has ratified the amendments. See, e.g., Barriga & Grover, supra note 58, at 532 (“Since [the amendment] enters into force for each ratifying state party individually under 121(5), the Court would have no jurisdiction whenever the amendment has not entered into force for any of the states parties involved.”). However, if the Article 5(2)/Article 12 theory is based on the proposition that states parties already accepted the Court’s jurisdiction over the crime of aggression when they became parties to the Rome Statute, it is not self-evident why ratification of the aggression amendments by either the alleged aggressor or the alleged victim would be necessary in order for the Court to be able to exercise jurisdiction. The fact that the proponents do not appear toaccept this seemingly natural extension of their theory as a plausible result would seem further to undercut the logic of the Article 5(2)/Article 12 theory.

78 The complete text of Article 5(1) is as follows:

The jurisdiction of the Court shall be limited to the most serious crimes of concern to the international community as a whole. The Court has jurisdiction in accordance with this Statute with respect to the following crimes:

  1. (a)

    (a) The crime of genocide;

  2. (b)

    (b) Crimes against humanity;

  3. (c)

    (c) War crimes;

  4. (d)

    (d) The crime of aggression.

79 See Parliament of the Commonwealth of Australia, Joint Standing Committee on Treaties, Report 45: The Statute of the International Criminal Court 46 (May 2002), at

In relation to the crime of aggression, advice from the Attorney-General and the Minister for Foreign Affairs was that the crime has not yet been defined and that it cannot be added to the Court’s jurisdiction until a definition is adopted by the State Parties. The earliest that the crime could be added to the Court’s jurisdiction is 7 years after the establishment of the Court. At this time, a State Party may decline to accept the definition, in which case the Court may not exercise jurisdiction over that crime when committed by the nationals of that State Party or on its territory.

80 Message relatif au Statut de Rome de la Cour pénale internationale, à la loi fédéerale sur la coopéeration avec la Courpénale internationale ainsi qu’à une réevision du droit péenal [Message on the Rome Statute of the International Criminal Court, the Federal Law on Cooperation with the International Criminal Court, as Well as a Revision of the Criminal Law], La Feuille Fédérale 359, 393 (2000 VII) (dated Nov. 15, 2000) (emphasis added) (authors’ translation), at

Interestingly, the issue also came up much earlier in the context of commentators who argued that the fact that the definition of the crime of aggression remained to be decided should not deter the United States from becoming a party to the Rome Statute. Such commentators argued that, if amendments defining aggression were later adopted, the Court’s jurisdiction would not apply against the nationals of a state that did not ratify the amendments. See, e.g., Sands, Philippe J.,The Future of International Adjudication, 14 Conn. J. Int’l L. 1, 9 (1999) (emphasis added):

The specter was raised that in the event that the United States decided to launch a military attack against another state, the prosecutor of the International Criminal Court might be able to commence proceedings directly against a United States President for aggression. In my view the fear is misplaced: it is clear from the Statute that the definition of aggression has not been settled and jurisdiction on this head will not apply until there is a definition of aggression established by amendment of the Statute. Since such amendment cannot take effect without ratification by seven-eighths of the parties to the Statute and will not cover nationals of states not ratifying, there is no prospect of a charge of aggression being laid against a United States national in the absence of United States ratification of the amendment.

81 One argument that has been raised is that paragraph 1 of Resolution RC/Res.6 says that the amendments “shall enter into force in accordance with article 121, paragraph 5” but does not say that jurisdiction created pursuant to it will operate in the same way as would be the case under (other) amendments that enter into force under that pro vision. Under this argument, the language in paragraph 1 of Resolution RC/Res.6 means that the first sentence of Article 121(5) applies but that, somehow, the second sentence does not apply.See Astrid R. Coracini,More Thoughts on “What Exactly Was Agreed in Kampala on the Crime of Aggression, “ Ejil: Talk! (July 2, 2010), at But it is hard to understand why the second sentence—which is a sentence specifically about the effect on jurisdiction of amendments that enter into force in accordance with the first sentence—would be inapplicable. The amendment adopted by the Kampala conference earlier during the night of adopting the aggression amendments—ICC Resolution RC/res/.5 (June 10, 2010), often referred to as the Belgian Amendment— used the same phrase in specifying that the amendment “is subject to ratification or acceptance and shall enter into force in accordance with article 121, paragraph 5,” and there has been no serious argument that the second sentence of Article 121(5) should not apply to it. Perhaps more importantly, the drafts of the aggression amendments developed by the Special Working Group in the run-up to Kampala all contained a version of the same sentence, with the language bracketed to show that the only thing unclear was whether it was Article 121(4)or Article 121(5)in accordance with which the amendments would enter into force. See, e.g., Report of the Special Working Group on the Crime of Aggression, App. I, in ICC Doc.ICC-ASP/7/20/Add.1, ch.II, Annex II(language by which Review Conference would adopt the amendments, “which are subject to ratification or acceptance and shall enter into force in accordance with article 121, paragraph [4/5]of the Statute”).See Conference Room Paper on the Crime of Aggression,in UN Doc. RC/WGCA/1, Annex III (May 25, 2010). The debate about whether to refer to Article 121(4) or Article 121(5) was consistently cast in terms of (1) the effect it would have on the conditions for exercising jurisdiction and (2) the implications that a decision to refer to Article 121(5) would have because the second sentence would then apply. All this preparatory work makes it even less plausible that the reference to “Article 121(5)” should be interpreted to mean that the first sentence of that article applies but that the second sentence is irrelevant.

82 ICC Res. RC/Res.6, supra note 1, para. 1.

83 Id., para. 3 (emphasis added).

84 Id., para. 4 (emphasis added).

85 Id., para. 5 (emphasis added).

86 Id., Annex I (emphasis added).

87 See, e.g., Article 15 bis (2) (jurisdiction can only be exercised one year after ratification or acceptance of the amendments by thirty states); Article 15 ter(2) (same); ICC Res. RC/Res.6, supra note 1, Annex III (referring to the Understandings as “Understandings regarding the amendments to the Rome Statute”) (emphasis added). Similarly, the depositary notifications by the secretary-general upon notification of ratification similarly refer to the provisions as “amendments,” see, e.g., Depositary Notification, UN Doc. C.N.249.2012.TREATIES-XVIII.10.b (June 11. 2010), at (Liechtenstein); Depositary Notification, UN Doc. C.N.636.2012.TREATIES-XVIII.10.b (June 11, 2010), at (Trinidad and Tobago), and, in fact, the secretary-general’s authority to circulate documents under Article 121(7) of the Rome Statute, supra note 1, is specified as an authority to circulate amendments.

88 It is also worth noting that Article 123(3) of the Rome Statute, supra note 1, provides that “[t]he provisions of article 121, paragraphs 3 to 7, shall apply to the adoption... of any amendment to the Statute considered at a Review Conference.” It was, of course, specifically understood that the amendments to be considered at the Review Conference would include those on the crime of aggression.

89 Rome Statute, supra note 1, Art. 122(2). Unlike the situation under Article 5(2), Article 122 does not say that the adoption of the amendments must take place “in accordance with articles 121 and 123.”

90 Statement at the Review Conference of the International Criminal Court, supra note 47.

91 Statement of Japan, in Statements by States Parties in Explanation of Position Before the Adoption of Resolution RC/Res.6, in ICC Doc. RC/11, supra note 1, Annex VII, at 121.

92 See Barriga, supra note 76, at 32, 42. The records from Kampala reflect that provisions that would have suggested that such declarations had to be submitted before a date certain, or before ratification, were considered but that the parties declined to include such provisions in the amendments that were ultimately included in Resolution RC/Res.6. See, e.g., Declaration (Draft of 9 June 2010 16h00), in Trahan, J., The Rome Statute’s Amendment on the Crime of Aggression: Negotiations at the Kampala Review Conference, 11 Int’l Crim. L. Rev. 49, App. D (2011). In this compromise proposal between the proposal submitted by Argentina, Brazil, and Switzerland (Appendix A) and that submitted by Canada (Appendix B), Article 15 bis (4ter) would state that a declaration of nonacceptance “may be submitted to the Secretary General of the United Nations at any time before December 31, 2015 or, in the case ofStates that ratify or accede to the Rome Statute after that date, upon ratification or accession.”See Trahan, supra, at 73 n.97, Apps. A, B.

93 ICC Res. RC/Res.6, supra note 1, para. 1. Some have pointed to the language in paragraph 1 as suggesting that the parties at Kampala must have intended the Court to have jurisdiction with respect to alleged acts of aggression committed by states parties that did not ratify or accept the amendments unless they lodged such a declaration. Besides not being logically true—for example, the very discussion above demonstrates how states parties might want to use an advance opt-out to protect themselves from the Court exercising jurisdiction with respect to acts of aggression alleged to have been committed before they accept or ratify the amendments—such a result would, as we have seen above, be inconsistent with Article 121(5) of the Rome Statute. It thus would have been possible to achieve this result only if the parties had amended Article 121(5)—something that, to our knowledge, none of the proponents have claimed to have been agreed at Kampala, and something that could not have been done with respect to those states that decline to ratify or accept the amendments.

94 A number of states could potentially agree upon the wording of such an opt-out and enter it at the same time, For a description of how such a collective opt-out might be fashioned, see Esbrook, Leslie, Exempting Humanitarian Intervention from the Definition of the Crime of Aggression: Ten Procedural Options for 2017, 55 Va. J. Int’l L. (forth coming 2015).

95 Article 4 of the Constitutive Act of the African Union (2000), at, provides for “the right of the Union to intervene in a Member State pursuant to a decision of the Assembly in respect of grave circumstances, namely: war crimes, genocide and crimes against humanity,” and “the right of Member States to request intervention from the Union in order to restore peace and security.” For a fuller discussion of this “regional framework” possibility, see generally Esbrook, supra note 94.

96 At this writing, twenty-three states parties have ratified the aggression amendments.

97 ICC Doc. RC/11, supra note 1, at 127 (statement of U.S. Legal Adviser Harold Hongju Koh).

98 Id. at 122.

99 See, e.g., id. at 123 (Norway: emphasizing the need for “an assessment as to whether any further clarification would be called for as a precondition for the entry into force”). Indeed, there was not even consensus on whether it would be appropriate to allow aggression cases to proceed on the basis of state referral or proprio motu. See id. at 122 (France: Article 15 bis “restricts the role of the United Nations Security Council and contravenes the Charter of the United Nations”); id. at 124 (“The United Kingdom has fundamental issues of principles at stake with regard to aggression” and, in that respect, “draw[s] attention to Article 39 of the United Nations Charter.”).

100 Id. at 126 –27.

101 An important, bipartisan report submitted by then Senators Kerry and Lugar of the U.S. Senate Committee on Foreign Relations underscored the importance of these provisions from the perspective of the U.S. domestic audience. Among other things, the report noted:

The proposed aggression regime is flawed in several respects, but nonetheless contains important protections for U.S. interests. Most significantly, U.S. persons, including U.S. officials and military members, could not be investigated or prosecuted for aggression by the ICC without the consent of the United States. The proposed regime will not enter into force for at least seven years, and will do so only after a further decision by the ICC’s parties to bring it into force. U.S. participation atthe Kampala Conference played an important role in securing these protections.

International Criminal Court, Review Conference, Kampala, Uganda, May 31–June 11, 2010: A Joint Committee Staff Trip Report Prepared for the Use of the Committee on Foreign Relations, United States Senate, 111th Cong., 2d Sess., at v (Sept. 2, 2010). With respect to the delay provision, the report stated:

Because the aggression regime will not go into effect for at least seven years, the United States will have opportunities to further address concerns not resolved by the outcome. It could seek greater clarity in the definition of aggression, either through changes to the definition or the elements of crimes accompanying it, or through further understandings. It will also have the opportunity to consult with allies and to develop plans to mitigate risks an ICC aggression regime might pose to the ability to plan and carry out coalition military operations.

Id. at 10.

With respect to the definitions, the report stated:

Interpretive understandings adopted in connection with the definition serve to mitigate some of its deficiencies, but the definition remains an unsound basis for addressing these issues. Were the definition to influence the future development of international law outside the context of the ICC, future U.S. leaders could face increased criticism in connection with some decisions regarding the use of force, including claims that their decisions amount to criminal conduct.


* This article is written in their personal capacities and does not necessarily represent the views of the U.S. Department of State or the U.S. government. The authors are grateful to Mara Revkin of Yale Law School for her fine research assistance.

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