CYIL Vol. 5, 2014

THE DEFINITION OF AGGRESSION AND THE USE OF FORCE act of aggression for the Kampala “crime of aggression” is given in Art. 8 bis (1) “by its character, gravity and scale” which “constitutes a manifest violation of the Charter of the United Nations”. These general notions of character, gravity, scale or manifest violation may lead in some cases to a different, rather subjective interpretation of these terms. This is mainly a problem for the decision- making of the ICC itself. On the other hand, the decisions of the ICC will have impact on the understanding of aggression as prohibited in the jus ad bellum . It would be useful to specify the customary international law prohibiting aggression and to analyze the differences with regard to the Kampala definition in international law. Different opinions were expressed as to if Art. 5 (1) of the 1974 Definition of aggression confirms existing international customary law. 87 This definition was centred on state responsibility for acts of aggression and not on the criminal responsibility of individuals. The Kampala definition of the crime of aggression was designed predominantly as a judicial definition for the ICC. Serious concern has been expressed that this definition may do harm to the jus ad bellum definition of aggression. In M. O’Connel’s view, there are now two competing definitions of aggression in public international law, and it is perceived that the Kampala definition departs from the customary law crime of aggression and the jus ad bellum definition of aggression. 88 The concern about the future impact of the Kampala definition on the jus ad bellum definition of aggression seems to be justified. It will also depend on the effectivity of the ICC jurisdiction in prosecuting crimes of aggression which may substantially affect the jus ad bellum understanding of aggression.

87 Dinstein, Y., supra note 1, p. 135. 88 O’Connell, M., supra note 49.

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