The crime of aggression as custom and the mechanisms for determining acts of aggression.

Author:Jia, Bing Bing
Position:Response to Harold Hongju Koh and Todd F. Buchwald, American Journal of International Law, vol. 109, p. 257, April 2015

The fallout from the 2010 Kampala Review Conference for the United States has been explained by Harold Koh and Todd Buchwald, who were officially involved in the negotiations at the conference. (1) The concerns they enumerate serve to implicate, inter alia, two issues of broad importance for the international community: the definition of the crime of aggression, and the clear divide between the positions of the permanent members of the UN Security Council and the rest of the Kampala participants with respect to the Council's role in implementing the Rome Statute's new provisions on the crime of aggression. This Note, which focuses on those two issues, is partly a response to some of their criticisms and partly an independent assessment of the consequences of the Review Conference. It also evaluates the Kampala amendments to the Rome Statute (2)--in particular, Articles 8 bis, 15 bis, and 15 ter--from the perspective of customary law and considers their impact on the role assigned to the Council under the UN Charter.

The prospect of the amendments on aggression entering into force (3) is especially significant for the Council's permanent members. A central concern of theirs is that the Council will no longer exercise sole control over determining the existence vel non of an act of aggression. (4) Depriving the Council of exclusive control over the maintenance of peace and security effectively amounts to a reform of its role without amending the UN Charter, subject to two potential limitations that are now included in the Kampala amendments. First, those Rome Statute amendments result in sharing only one of the Council's prerogatives under Chapter VII with the International Criminal Court (ICC). Nonetheless, allowing a judicial body to exercise adjudicative authority over issues embedded in high politics constitutes a fundamental shift in international relations and in the structure of the Charter. Second, the Council may respond to the prospect of an ICC investigation or prosecution by invoking Article 16 of the Rome Statute to defer such proceedings, but such action may be difficult in practice as it requires securing enough votes among its members to adopt a binding resolution to defer and then to renew that deferral every twelve months. (5)

Beyond Council-specific concerns, the integration of the Kampala amendments into customary law could contribute to the formation of objective criteria to be used in evaluating whether a situation constitutes aggression under international law. (6) The impact of that development may dwarf the significance of specific instances in which the ICC exercises jurisdiction over a crime of aggression. (7)

This Note will consider the following questions: first, whether the definition contained in Article 8 bis reflects or will reflect customary law; second, whether the Kampala amendments concerning jurisdiction can affect non-states parties, which may want to keep themselves safely out of the reach of the ICC; and third, whether prospective ICC decisions pursuant to the Kampala amendments will have adverse implications for the Council's work under Article 39 of the UN Charter.


    During the Princeton Process, the Special Working Group on Crimes of Aggression considered three "leading definitional models": (8) a formal expression "war of aggression"; reference to Article 2(4) of the UN Charter; (9) and the language of Resolution 3314 (XXIX) adopted by the UN General Assembly in 1974. (10) The Kampala amendments eventually adopted, in part, the language of Resolution 3314, (11) which embodied the mixed definitional approach prevalent in the pre-Rome Conference era. (12)

    There is no question as to the customary law status of the crime of aggression. (13) Nonetheless, the scope of the crime remains disputed. (14) While this situation is reflected in certain ambiguities within the text of Article 8 bis, (15) these ambiguities may not prevent that provision from being treated as the codification of customary law. The first and decisive step of the march toward codification occurred at the 1998 Rome Conference, when participants built on the foundation of the Nuremberg and Tokyo Trials by including the crime of aggression in Article 5(1) of the Rome Statute. (16)

    There were two ways to deal with the challenge of reaching an acceptable definition of the crime at Kampala. (17) One approach would have been to hew closely to state practice, thereby effectively reducing the problem to a technical drafting exercise. This approach would draw largely on treaties and jurisprudence on the crime of aggression stemming from the 1940s trials at Nuremberg and Tokyo. (18) Broadly speaking, it would have reflected the Nuremberg and Tokyo Charters (Articles 6(a) and 5(a), respectively), UN General Assembly Resolution 95 (I) of December 11, 1946, Principle VI (a) of the Nuremberg Principles, (19) Principle 1 of UN General Assembly Resolution 2625 (XXV) of October 24, 1970, (20) and Article 5(2) of UN General Assembly Resolution 3314 (XXIX) of December 14, 1974. (21) It is plain, however, that the end result, Article 8 bis, does not take this route. (22)

    The drafters of Article 8 bis followed a second approach. They chose to develop custom, not simply codify it. (23) As a result, the new definitional elements of Article 8 bis will remain treaty based until integrated into the corpus of customary law through subsequent state practice and opinio juris. Indeed, the Rome Statute anticipated this situation in Article 10, which provides that "[n]othing in this Part shall be interpreted as limiting or prejudicing in anyway existing or developing rules of international law for purposes other than this Statute." (24) Likewise, the Kampala negotiators appeared to anticipate having an impact on customary law, particularly insofar as they incorporated the definitional elements of aggression in Article 8 bis(2) from Resolution 3314. (25)

    The combination of codification and progressive development in Article 8 bis merits the following three comments.

    First, the Kampala amendments and Article 8 bis(2) partly reflect the limited stage of evolution that this body of international law has reached. These limits prevented the participants and observer states at the Review Conference from finding common ground to go further. For instance, Article 8 bis's omission of nonstate actors, unquestionably a shortcoming from a practical point of view, (26) was a product of prevailing attitudes and state practice.

    Second, critics of the Kampala amendments consider Resolution 3314 a "political declaration." (27) By granting the Council latitude to determine what constitutes an act of aggression, (28) the resolution suggests there is no limit on the Council's freedom to add to (or subtract from, perhaps) the enumerated acts of aggression in that resolution. The significance of this openness can only be understood in light of the Council's decisions to use political solutions to restore peace and security whenever possible. As others have shown, the Council has never referenced the Assembly definition of aggression, and the Assembly itself and the International Court of Justice (ICJ) have done so only rarely. (29) The Council and Assembly have been reluctant even to use the terms "aggression," "aggressive acts," or "acts of aggression" in their respective resolutions. (30) Thus, the resolution's list has not accumulated sufficient density of practice to be accepted as customary law. The Kampala amendments may mark an important step in that direction, however, because they were adopted by consensus by over a hundred states parties to the Rome Statute. While the list in Article 8 bis(2) (a)-(g) is open-ended, (31) permitting states to augment it, actions covered in that list might be seen as presumptively within the customary crime by courts. Nevertheless, the ICC will need to take into account the Council's limited practice on point, both because that practice may be relevant for the purposes of an amended Rome Statute (32) and because the ICC will presumably want to avoid any conflict with Council practice. Of course, the highly politicized nature of debates within the Council may limit their relevance for a judicial body.

    Third, it matters what states have said with respect to the Kampala amendments and what they have done subsequent to the Kampala conference. The speed at which the Kampala amendments are being ratified is notable. Twenty-three states, (33) including Germany, (34) have done so. Further, the bulk of the doubts expressed by China, Russia, and the United States after the adoption of the Kampala amendments were seemingly geared toward the way in which the aggression jurisdiction may be exercised by the ICC. It might be argued, based on their statements, that at least two of those three countries were not opposed to the definition of the crime set forth in Article 8 bis. As Koh and Buchwald make clear, the United States clearly does not consider Article 8 bis to reflect customary law. (35) Similar doubts were expressed by Israel in 2010. (36) This skeptical attitude of the two countries may also potentially extend to Resolution 3314's annexed definition of aggression. (37)


    The jurisdictional amendments to the Rome Statute, Articles 15 bis and 15 ter, establish intricate mechanisms for the exercise of the ICC's jurisdiction over the crime of aggression. The concerns of some of the Security Council's permanent members relate to the tension between the ICC's jurisdiction and the Council's competence. Concurrent competence, in their view, is simply not acceptable. (38)

    Historically, the General Assembly's few purported findings that acts of aggression have been committed have long encountered resistance from some member states. (39) Even though the UN Charter grants the Assembly limited power to make...

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