There can be no more dramatic evidence of the progress and evolution of human rights norms than in the fact that the first international war crimes tribunals, created in the aftermath of the Second World War, made widespread use of the death penalty and that their successors, created by the Security Council in 1993 and 1994, prohibit it. Over the forty-nine years that transpired between the trials at Nuremberg and those at The Hague and Arusha, States throughout Europe, Africa, Asia and the Americas gradually limited the scope of the death penalty and, ultimately, abolished it in peacetime and wartime. In mid-1995, the Secretary-General of the United Nations concluded, in his quinquennial report on capital punishment, that "there has been a considerable shift towards the abolition of the death penalty both de jure and in practice."(1) In the same year, Amnesty International reported that the death penalty had been abolished, either de jure or de facto, in a majority of States.(2)
This evolution in criminal law practice was accompanied by developments in human rights norms. Article 2 of the European Convention on Human Rights, the first binding human rights norm dealing with the death penalty, expressly authorized capital punishment as an unqualified exception to the right to life.(3) Subsequent texts, however, limited its scope by excluding certain categories of individuals from the death penalty, prescribing that it could only be imposed for the most serious crimes and insisting on the most rigorous procedural safeguards.(4) By the 1970s, full-fledged abolitionist norms, in the form of protocols to the conventions, were already being drafted and adopted by the relevant international organizations over the course of the next decade.(5) As of May 1993, when the Security Council ruled that the International Criminal Tribunal for Yugoslavia would not impose the death penalty, these instruments had rallied nearly fifty States.
The general subject of the abolition of the death penalty in international law has been the subject of other works.(6) This Article seeks only to examine the issue of the death penalty in relation to what are undoubtedly the most serious crimes--i.e., international crimes that are broadly grouped within the rubrics of war crimes and crimes against humanity. Yet against this background, valuable conclusions about the spread of universal human rights norms and their evolution shall be drawn.
II. POST-SECOND WORLD WAR TRIALS
When the argument nullum crimen nulla poena sine lege was invoked by the Nazi defendants, the Nuremberg Tribunal replied that the infractions charged had been defined in such instruments as the Regulations annexed to the fourth Hague Convention of 1907.(7) Even if these instruments were not necessarily applicable to the conflict in a technical legal sense, they had achieved the status of customary law. However, although the Hague Regulations set out many norms comprising the laws and customs of war, they did not establish a scale of sanctions or set a maximum punishment. Thus, they respect the norm of nullum crimen but fall short when it comes to nulla poena. There was some authority for the notion that international law had already recognized the death penalty as a maximum sentence in the case of war crimes, and therefore no breach of the rule prohibiting retroactive punishments had occurred.(8) It was said at the time that "[i]nternational law lays down that a war criminal may be punished with death whatever crime he may have committed."(9) The 1940 United States Army Manual Rules of Land Warfare declared that "[a]ll war crimes are subject to the death penalty, although a lesser penalty may be imposed."(10) A post-war Norwegian court, in answering a defendant's plea that the death penalty did not apply to the offense charged because it had been abolished for such a crime under domestic law, found that violations of the laws and customs of war had always been punished by death under international law. …