CYIL Vol. 6, 2015

AGGRESSION ȃ THE SUPREME INTERNATIONAL CRIME OR NOT A CRIME AT ALL? and the number of relevant trials at the domestic or international level should be taken into account. 55 This, however, brings us back to the history and morality argument. Overall, Bassiouni´s definition(s) of international crimes are somewhat confusing as they put together the elements of such crimes, the characteristic of the categories from which potential candidates for this qualification come, as well as the legal implication of the qualification. The concept of international crime or crime under international law has not so far secured a uniformly accepted definition. Its absence obviously makes it uneasy to determine whether a certain act – for instance aggression – qualifies as an international crime or not. Yet, despite the lack of a definition, there seems to be at least a tentative consensus on some of the elements that an international crime should reveal. Such elements first came out during the post-WWII trials, when the defence challenged the jurisdiction ratione materiae of the two international tribunals. In 1995, they were largely confirmed in the ICTY Decision quoted above. And even more recently, they got support at the Rome and Kampala Diplomatic Conferences: although no general debate about international crimes took place, states were referring to similar elements when qualifying certain acts as such (or when denying the qualification). Under these elements, an act cannot become an international crime unless: it has a legal basis in a rule of international law; this rule protects important universal values; this rule is specific and clear (especially as far as the definition of the crime is concerned); and the rule entails individual criminal responsibility. The elements are cumulative and have to be present at the same time. 3.2 The Concept of International Crime and the Crime of Aggression There can little doubt that genocide, crimes against humanity and war crimes exhibit the four elements listed at the end of the previous subsection. This paper argues that, at the current stage of development of international criminal law, the same applies, despite some of its particularities, to the crime of aggression. The first two elements do not seem to give rise to serious contentions. The prohibition of aggression certainly has a legal basis in the rules of international law and this rule protects important universal values. It is more controversial whether the rule entails individual criminal responsibility and whether it is specific enough (i.e. whether there is a generally accepted definition of a crime of aggression). Aggression was to be outlawed at the international level as early as in 1923, when the draft Treaty of Mutual Assistance declared that “aggressive war is an international crime”. 56 The same formulation appeared in the 1924 Protocol for the Pacific Settlement of International Disputes and the 1927 Declaration issued by the Assembly of the League of Nations. In 1928 in the Briand-Kellog Pact the state parties “condemn recourse

55 Ibid., p. 70. 56 Cit. in Historical Review of Developments relating to Aggression, op. cit., p. 30.

15