War of aggression as a crime against peace

The paucity of meaningful sanctions calculated to enforce respect for legal norms is a pervasive problem in every branch of international law, but nowhere is the need for such sanctions more evident than in the domain of the jus ad bellum. Even at the embryonic stage of the process culminating in the imposition of a legal ban on the use of inter-State force, it was generally recognized that, unless coupled with effective sanctions, the interdiction of aggressive war was liable to be chimerical. To be effective, sanctions in this context must go beyond the bounds of State responsibility (see supra, Chapter 4, F, (b)). Only if it dawns on the actual decision-makers that when they carry their country along the path of war in contravention of international law they expose themselves to individual criminal liability, are they likely to hesitate before taking the fateful step.

Already at the end of World War I (prior to the proscription of war by positive international law), plans were made to prosecute the German Kaiser, Wilhelm II, on account of his personal responsibility for the War. In Article 227 of the Versailles Treaty of Peace, the Allied and Associated Powers charged the Kaiser with ‘a supreme offence against international morality and the sanctity of treaties’.