The adoption of the Rome Statute of the International Criminal Court crowns developments underway for many decades in the establishment of an international tribunal with jurisdiction over serious international crimes such as genocide, crimes against humanity, war crimes and aggression. Although the Statute excludes the death penalty, the question was vigorously debated during the 1998 Rome Conference where it was adopted. Earlier models of international justice considered capital punishment to be appropriate for crimes of such gravity. This chapter considers the evolution of the issue of capital punishment in the field of international criminal law.

There is some authority for the proposition that war crimes are punishable by death as a matter of international law. The Lieber Code, promulgated by President Abraham Lincoln to govern the conduct of the Union Army during the American Civil War and often held up as an early codification of the laws and customs of war, made frequent reference to the death penalty as an appropriate punishment. More recently, in the commentary on war crimes trials held following the Second World War, the United Nations War Crimes Commission declared that ‘[i]nternational law lays down that a war criminal may be punished with death whatever crime he may have committed’. A post-Second World War Norwegian court answered a defendant's plea that the death penalty did not apply to the offence as charged, because the death penalty had been abolished for such a crime in domestic law, by finding that violations of the laws and customs of war had always been punishable by death at international law.