Aggression in International Law

Abstract

The crime of aggression, or crime against peace, was first introduced in the constituent instrument establishing the Nuremberg International Military Tribunal (IMT) (the London Charter, 1945) at the end of World War II. It was also included in the Charter of the Tokyo International Military Tribunal for the Far East (IMTFE) and Control Council Law No. 10, 1945. The criminalization of aggression in these instruments constitutes the culmination of a process that started at the end of World War I, with the arraignment of the German emperor Wilhelm II, by virtue of Article 227 of the Peace Treaty of Versailles, “for a supreme offence against international morality and the sanctity of treaties.” The prosecution of the crime of aggression before the Nuremberg and Tokyo IMTs met with strong criticism concerning the breach of the principle of legality (nullum crimen sine lege). However, the United Nations (UN) General Assembly, in G.A. Res. 95(I) (UN General Assembly 1946, cited under General Assembly Resolutions), and the International Law Commission (ILC), in the “Formulation of the Nürnberg Principles” (Yearbook of the International Law Commission 2 1950), endorsed the existence of the crime of aggression in customary law, with no opposition on the part of states. Hence, in the early 21st century it is universally accepted that the crime of aggression exists in customary law, although its precise definition, for the purposes of individual criminal responsibility, has been a matter of contention. No prosecutions for aggression followed the Nuremberg and Tokyo trials, and this crime remained in a state of lethargy until the establishment of the International Criminal Court (ICC) in 1998. Article 5, ICC Statute, includes aggression among the crimes within the Court’s jurisdiction. At the same time, Article 5(2) stipulates that the jurisdiction of the Court would not be exercised for aggression until a generally accepted definition of the crime was adopted. This definition was ultimately agreed upon at the first Review Conference of the ICC Statute, in Uganda (Kampala Conference), in June 2010 (new Article 8bis). The crime of aggression is closely connected with the resort to force by a state, unlike war crimes, genocide, and crimes against humanity, in which individual criminal responsibility is independent of the existence of state responsibility. Moreover, perpetrators of aggression, unlike the other three crimes, are exclusively state officials, particularly in the highest echelons of the state. The adoption of a definition of the crime of aggression in the ICC Statute is a major breakthrough that may clear the way for prosecutions of crimes against peace in the future, especially after the activation of the ICC jurisdiction over the crime of aggression in July 2018.