CYIL Vol. 5, 2014

THE DEFINITION OF AGGRESSION AND THE USE OF FORCE Questions of motive and intent were discussed e.g. by the drafting of the 1974 Definition of Aggression. There was deep disagreement on the role of animus aggressionis in the drafting of the Definition of Aggression. The ICJ in the Nicaragua case left the questions of motive and intents aside in its reflections. Pursuant to A. Cassese it would be a mistake to believe that, without an exhaustive definition of aggression, (his Article was written before 2010) Kampala definition perpetrators of this crime may not be prosecuted and punished. He observed that some traditional forms of aggression are prohibited by customary international law and that customary norms are basically those envisaged by the 1974 Declaration. The ICJ in the 1986 Nicaragua case confirmed that Art. 3(g) reflected customary international law. 60 The ICJ in the Barcelona Traction case stated that the principles of international law outlawing acts of aggression are obligations erga omnes. 61 The concept of erga omnes obligations expressed by the Court was generally endorsed by the ILC and applied to the breach of international obligations which constituted “international crimes”. 3.5 The Relationship between “Act of Aggression”, “Armed Attack” and “Armed Intervention” – Additional Remarks In Art. 51 and 39 of the UN Charter two different notions are contained: “armed attack” and “act of aggression”. For purposes of self-defense the term of “armed attack” was preferred in Art. 51 over the term of “aggression”. Nevertheless, in the also authentic French version of the UN Charter the term “armed attack” is not expressed as “attaque armée” but as “aggression armée” , which may indicate that the original French thinking was in favour of the identity of both terms(?!). Neither the notions of “armed attack” nor of “aggression” were defined during the UN Charter preparation. The ICJ in the Nicaragua case considered what constituted an armed attack. The sending of armed bands in the Court’s opinion constitutes an armed attack provided the classified “scale and effects”. The 1974 Definition of Aggression gave the same guidance to any reasonable interpretation. The decisive features mentioned by the ICJ were “the scale and effects” of the use of force and, in second place, the circumstances and motivations of the attack. 62 This is a subjective appreciation which might be, of course, rather controversial. The Court was sharply criticised for its narrow view of armed attacks, mainly by American representatives and lawyers, for consequent limitation of the U.S. right to collective self-defense. 63 Y. Dinstein asserted that there is no cause to remove small scale armed attacks from the spectrum

60 ICJ Reports, Judgements of 27 June 1986 Case concerning military and paramilitary activities in and against Nicaragua,14, para. 195. 61 See Barcelona Traction Light and Power Company Ltd. Judgement, 1970 I.C.J., p. 32. 62 ICJ Reports, Judgements of 27 June, supra note 60, para. 195 and 231. 63 Hargrove, J. L., The Nicaragua Judgment and the Future of the Law of Force and Self-defence, AJIL 1987, No. 1, p. 135.

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