The notion of aggression is as old as human society, but it is not until the beginning of the 20th century that the idea of aggression acquires a legal meaning in international law. The League of Nations was used as the springboard to launch the first few efforts towards banning aggressive wars and, in order to do so, to define aggression. This process has been ongoing for almost a century. Many have insisted that this process culminated with the adoption of the General Assembly resolution 3314 (XXIX) of 14 December 1974, adopted by consensus. Yet, events within the framework of the International Criminal Cour (ICC) show that that is not the case

The objective of this study is to close a gap in the existing literature on the development of the notion of aggression since the question was adopted by the League of Nations in the 1920s until the recent developments in the context of the Special Working Group on the Crime of Aggression of the Assembly of States Parties to the ICC. Furthermore, this thesis aims at underlining that blind insistence on the adoption of resolution 3314 (XXIX) in the context of the ICC statute is totally inadequate, as this resolution is the result of a process aimed at satsfying other goals and does not observe the strict conditions requiered by criminal law. In the context of the definiton of aggression, after so many years, so many failures, and so many efforts, what is important is to submit a proposal that fits into the "political interests" of States in such a way that they would be willing to accept it. In order to do so, this thesis provides a definition proposal that advances both the main interest of adopting a rule on agression -to punish those accused of having committed certain acts that are criminally reprehensible in the eyes of the international community as a whole- while assuaging fears in the different camps concerning issues of sovereignty, Security Council powers, lawful uses of force, etc. The objective is not to propose a rule on the crime of aggression, but rather the "contours" of a definition with all the elements that need to be taken into consideration in order to make a rule on aggression legally sound