The international enforcement of individual criminal responsibility for violations of international law was first envisaged in 1915 by France, Great Britain and Russia following the massacre of more than one million Armenians. These countries qualified the event as a ‘crime against civilisation and humanity’ for which the members of the Turkish Government should be held responsible. In 1946, the prosecutions of Nazis war criminals were the first effective international enforcement of individual responsibility for violations of the laws of war and crimes against humanity committed in international armed conflicts. As far as internal armed conflicts are concerned, the international enforcement of individual responsibility for war crimes per se was neither envisaged in the 1949 Geneva Conventions nor in Protocol II of 1977. The failure to provide for individual criminal responsibility for war crimes in Protocol II explains why up to the 1990s, violations of the laws of war, when committed during an internal armed conflict, were prosecuted as domestic crimes and did not attract international responsibility.

The past decade saw the extension of international criminal responsibility from conduct committed in international conflicts to similar conduct committed in internal conflicts. Violations of the laws of war committed in internal conflicts have been recognised as amounting to war crimes for which individual responsibility must be enforced at a national or an international level. Before, international criminal law was simply not applicable in the sphere of internal armed conflicts.