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A Historic Breakthrough on the Crime of Aggression

  • Stefan Barriga (a1) and Leena Grover (a2)

At 12:20 in the morning on Saturday, June 12, 2010, the Review Conference of the Rome Statute of the International Criminal Court in Kampala, Uganda, adopted by consensus a comprehensive package of amendments on the crime of aggression. States parties to the Rome Statute thereby delivered on their promise, reflected in Article 5 (2) of the Statute, to define the crime of aggression and to agree on the conditions for the Court’s exercise of jurisdiction over that crime. Despite a thorough and more than decadelong preparatory process, few, if any, had predicted such a substantive outcome on the crime of aggression in light of the serious disagreements on major questions, which persisted until the last days of the conference. The key elements of the final package are a definition of the crime of aggression, which limits criminal responsibility to leaders who are responsible for the most serious forms of the illegal use of force between states, and a complicated set of conditions for exercising jurisdiction. Investigations would be based on either a Security Council referral or state consent.

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1 International Criminal Court, Assembly of States Parties, Review Conference, The Crime of Aggression, ICC Doc. RC/Res.6 (June 11, 2010) [hereinafter Aggression Resolution]. The official records of the Review Conference, ICC Doc. RC/11 [hereinafter Review Conference Official Records], are available at Part I includes the proceedings, and Part II the resolutions, declarations, and various annexes. The Web site for the Assembly of States Parties,, provides access to all official records, general debates, and other records and documentation. The Rome Statute, July 17, 1998, 2187 UNTS 90, as well as other legal texts, information about situations and cases, and press releases, is available at

2 Article 121 contains a series of rules for amending the Rome Statute, and Article 123 requires the convening of a Review Conference to consider amendments to the Rome Statute seven years after its entry into force. On the controversial inclusion of the crime of aggression in the Rome Statute, see Zimmermann, Andreas, Article 5: Crimes Within the Jurisdiction of the Court , in Commentary on the Rome Statute of the International Criminal Court 129, 135-37 (Triffterer, Otto ed., 2008).

3 Within the Preparatory Commission, Silvia Fernández de Gurmendi served as coordinator of the Working Group on the Crime of Aggression. The Coordinator’s Paper and a list of proposals and documents relating to the crime of aggression are contained in UN Doc. PCNICC/2002/2/Add.2 (2002). See also Clark, Roger S., Rethinking Aggression as a Crime and Formulating Its Elements: The Final Work-Product of the Preparatory Commission for the International Criminal Court , 15 LEIDEN J. Int’l L. 859 (2002).

4 International Criminal Court, Assembly of States Parties, Continuity of Work in Respect of the Crime of Aggression, ICC Doc. ICC-ASP/1/Res.l (2002).

5 The final Princeton meeting on the crime of aggression was held at the Princeton Club in New York in June 2009.

6 The Princeton Process on the Crime of Aggression: Materials of the Special Working Group on the Crime of Aggression, 2003–2009 (Barriga, Stefan, Danspeckgruber, Wolfgang, & Wenaweser, Christian eds., 2009 ). This volume contains all the reports and other materials pertaining to this process up to June 2009. A collection of the complete travaux préparatoires (spanning the period from 1995 to 2010) and most relevant historical documents, as well as introductory commentary, is forthcoming from Cambridge University Press in The Travaux PrÉparatoires of the Crime of Aggression (Stefan Barriga & Claus Kreß eds., forthcoming).

7 Report of the Special Working Group on the Crime of Aggression, ICC Doc. ICC-ASP/7/20/Add. 1, Annex II, App. I (2009).

8 See United States Mission to the United Nations, Statement by Harold Hongju Koh, Legal Advisor, United States Department of State, Regarding Crime of Aggression at the Resumed Eighth Session of the Assembly of States Parties of the International Criminal Court (Mar. 23, 2010), at

9 Other aspects of the U.S. position—favoring both a consent-based regime and an exclusive role for the Security Council in “filtering” aggression cases—caused less of a stir as they conformed to well-known positions of other permanent members of the Security Council.

10 The details of the formal positions are as follows. Ambassador Wenaweser served as chair of the Special Working Group from its first meeting in September 2003 to its conclusion in February 2009 and as president of the Assembly of States Parties (and therefore the Review Conference) beginning in November 2008. In June 2009, Prince Zeid took over as chair of the working group-level negotiations on the crime of aggression. From that time until the end of the Review Conference, Ambassador Wenaweser and Prince Zeid worked closely together on the aggression negotiations. Ambassador Wenaweser formally took over the negotiations only in the final days of the conference in his capacity as president.

11 In the run-up to Kampala, the U.S. delegation was by far the most active non–state party in this process and was instrumental in organizing intersessional discussions in Glen Cove, New York (March 2010), and in Mexico City (May 2010). At the Review Conference itself, no state party or non–state party had more delegates in attendance dealing with the crime of aggression.

12 They suggested, in essence, that the definition of the crime of aggression in the Rome Statute would not automatically be considered a statement of customary international law, that the amendments themselves would not authorize domestic prosecutions regarding the use of force by other states, and that the Court’s jurisdiction could be delayed for several years. See Non-paper by the Chair: Further Elements for a Solution on the Crime of Aggression, Review Conference Official Records, supra note 1, pt. II, Annex III, App. IV, at 67.

13 Prince Zeid revised his initial “Conference Room Paper,” submitted in preparation of the Review Conference, twice in Kampala. These papers were attached to the Report of the Working Group on the Crime of Aggression, ICC Doc. RC/5, in Review Conference Official Records, supra note 1, pt. II, Annex III, at 45. Subsequently, Ambassador Wenaweser submitted three further non-papers, the last of which formed the basis for the Aggression Resolution (RC/Res.6) as adopted.

14 A genuine humanitarian intervention without Security Council authorization would, by its gravity and character, not fulfill the criterion of a manifest Charter violation since its legality under general international law is at least debatable. See Claus, Kreß, Time for Decision: Some Thoughts on the Immediate Future of the Crime of Aggression: A Reply to Andreas Paulus , 20 Eur. J. Int’l L. 1129 (2010).

15 For his account on this negotiation track and on the aggression negotiations as a whole, see Claus, Kreß & Leonie von, Holtzendorff, The Kampala Compromise on the Crime of Aggression , 8 J. Int’l Crim. Just. 11791217 (2010).

16 Remarkably, the delegation of Iran was willing to engage directly and constructively on this issue only a few hours after the UN Security Council had decided to strengthen the sanctions regime against Iran.

17 Aggression Resolution, supra note 1, Understanding 6.

18 Aggression Resolution, supra note 1, Understanding 7. An earlier draft suggested by the U.S. delegation would have explicitly required that each of the three criteria, considered by itself, would have to establish a “manifest violation.” The Canadian delegation disagreed; on its understanding of the language in draft Article 8 bis, the “manifest violation” could reflect a cumulative assessment. Accordingly, even though the individual elements might, each by itself, be something short of “manifest,” the elements considered together might be considered such.

19 Understanding 4 of the Aggression Resolution, supra note 1, provides:

It is understood that the amendments that address the definition of the act of aggression and the crime of aggression do so for the purpose of this Statute only. The amendments shall, in accordance with article 10 of the Rome Statute, not be interpreted as limiting or prejudicing in any way existing or developing rules of international law for purposes other than this Statute.

20 Understanding 5 of the Aggression Resolution, supra note 1, provides: “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.”

21 Eventually, Articles 15 bis and 15 ter.

22 In case of a controversial adoption of the amendments, the Article 121 (4) route would also entail the risk of a campaign against ratification, given the small blocking minority required: one-eighth of states parties could thereby thwart the efforts of the overwhelming majority.

23 The following countries expressed a preference for a consent-based regime: Albania, Andorra, Australia, Austria, Belgium, Bulgaria, Canada, Colombia, Croatia, Estonia, Fiji, France, Germany, Hungary, Ireland, Italy, Japan, Latvia, Luxembourg, Macedonia (FYROM), Mexico, the Netherlands, Norway, Paraguay, Peru, Poland, Portugal, New Zealand, Slovakia, Spain, Sweden, and the United Kingdom. The following countries clearly expressed a preference for a regime that is not based on the consent of the alleged aggressor state: Argentina, Belize, Bolivia, Botswana, Brazil, Burkina Faso, Chile, Congo, Costa Rica, Democratic Republic of Congo, Djibouti, Ecuador, Finland, Gabon, Ghana, Greece, Guinea, Guyana, Jordan, Kenya, Lesotho, Madagascar, Namibia, Nigeria, Republic of Korea, Romania, Samoa, Senegal, Slovenia, South Africa, Switzerland, Tanzania, Trinidad and Tobago, Uganda, Venezuela, and Zambia. The result of the roll call outlined here is based on the notes of the authors, who were present at that meeting. The result was not formally recorded.

24 Non-paper Submitted by Delegations of Argentina, Brazil and Switzerland as of6June 2010, Review Conference Official Records, supra note 1, Annex III, App. V, A.

25 Non-paper Submitted by the Delegation of Canada as of 6 June2010, Review Conference Official Records, supra note 1, Annex III, App. V, B.

26 Non-paper by the President of the Review Conference (June 10, 2010,11:00 p.m.). The non-paper itself was not issued as an official document. Nevertheless, this version of the non-paper was subsequently considered by the linguistic Drafting Committee and therefore published in the Review Conference Official Records, supra note 1, Annex 11(b), App. II.

27 Article 24(1) of the UN Charter reads: “In order to ensure prompt and effective action by the United Nations, its Members confer on the Security Council primary responsibility for the maintenance of international peace and security, and agree that in carrying out its duties under this responsibility the Security Council acts on their behalf.”

28 Conference Room Paper on the Crime of Aggression (Rev. 1), Review Conference Official Records, supra note 1, Annex III, App. II.

29 Conference Room Paper on the Crime of Aggression (Rev. 2), Review Conference Official Records, supra note 1, Annex III, App. I.

30 It is not unimaginable, however, that the prosecutor might uncover evidence of aggression of which the Council was unaware at the time of its referral—for example if a third state turns out to be “substantially involved” in the activities of rebel groups in the sense of Article 8 bis (2)(g). In such circumstances, the only way for the Council to exert control would be to suspend the investigation under Article 16 of the Statute.

31 See Non-paper by the President of the Review Conference, supra note 26.

32 Article 16 provides:

No investigation or prosecution may be commenced or proceeded with under this Statute for a period of 12 months after the Security Council, in a resolution adopted under Chapter VII of the Charter of the United Nations, has requested the Court to that effect; that request may be renewed by the Council under the same conditions.

33 Under the ABS proposal, Article 15 bis would have required ratifications by seven-eighths of states parties, not just an activation decision by states parties (by consensus or at least two-thirds of states parties present and voting in accordance with Article 112(7)(a) of the Rome Statute).

34 Rome Statute, supra note 1, Art. 121(3).

35 The enabling resolution states only that Article 121(5) governs the entry into force of the amendments. It does not explicitly address the related, but separate, question whether the Court may exercise jurisdiction over an alleged crime of aggression committed by a state party that has not ratified the amendments on the territory of a state party that has ratified them. The resolution hints at this possibility by noting that “any state party may lodge a declaration referred to in article 15 bis prior to ratification or acceptance.” But see infra note 38.

36 The beginning of the exercise of jurisdiction can take place in 2017 at the earliest. Aggression Resolution, supra note 1, Arts. 15 bis (3), 15 ter (3).

37 Articles 15 bis (5) and 15 bis (4) exclude the possibility of a non-state party accepting jurisdiction over the crime of aggression under Article 12(3) of the Statute. As confirmation, the reference to Article 12(3) was deliberately deleted in the final interpretive understandings accompanying these provisions, whereas all previous drafts of these understandings retained an explicit reference.

38 As the final package does not contain an explicit understanding on the question whether a nonratifying state party that has allegedly aggressed, but not opted out, may be subject to the Court’s jurisdiction under Article 15 bis, divergent interpretations on the issue have emerged after Kampala. The approach that Ambassador Wenaweser presented to the plenary on the morning of Thursday, June 10, 2010, was strongly based on Article 12(1) of the Statute, under which states parties have already accepted jurisdiction over the crime of aggression. Consequently, nonratifying and allegedly aggressing states parties that do not accept the Court’s jurisdiction under Article 15 bis would have to submit an opt-out declaration to prevent the Court from exercising jurisdiction. See the statements made in the 2010 debate of the UN General Assembly on the Report of the International Criminal Court, UN Doc. A/65/PV.41, at 8–9 (Switzerland), 17–18 (Brazil) (2010). See also Kreß & von Holtzendorff, supra note 15, at 1212; Wenaweser, Christian, Reaching the Kampala Compromise on Aggression: The Chairs Perspective , 23 Leiden J. Int’lL. 883 (2010). Those opposing this view maintain that the second sentence of Article 121(5) already precludes the Court from exercising jurisdiction with respect to nationals or the territory of nonratifying states parties. See, for example, the statements made by France and the United Kingdom during the general debate of the ninth session of the ICC Assembly of States Parties in December 2010. See also the U.S. statement made in the 2010 General Assembly debate, UN Doc. A/65/PV.41, at 26–27. In essence, both views coincide in that Article 15 bis is a consent-based regime, though opinions diverge as to whether active consent is required by the alleged aggressor state (that is, ratification) or passive consent only (that is, not to submit an opt-out declaration).

39 Kirsch, Philippe & Holmes, John T., The Birth of the International Criminal Court: The 1998 Rome Conference , 1998 Canadian Y.B. Int’l L. 3, 38 .

40 In 1947–1948, Ferencz was chief prosecutor in Nuremberg for the Einsatzgruppen case, which involved twenty-two defendants who were charged with murdering over one million people. All defendants were convicted, and the press hailed it as the “biggest murder trial in history.” Since then, Ferencz has argued tirelessly for recognizing international criminal law, defining the crime of aggression, and peace. He has published widely on these topics and played an integral role in the creation of the Court and in the work of the Special Working Group and the Review Conference on the crime of aggression. In gratitude, this article is dedicated to him.

* He served as the principal legal adviser to the chairs of the negotiations on the crime of aggression (see infra note 10) since 2003. She served as legal adviser to the chairs of the aggression negotiations since 2007.

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