On 17 July 1998, the Rome Statute of the International Criminal Court (hereinafter: the ICC Statute) was adopted. There is no doubt about the significance of the legislation of the ICC Statute to international criminal law. The discussion at the United Nations (UN) on the idea of an international court for criminal proceedings started soon after the establishment of the UN, in the legislation of the Genocide Convention and other works, but encountered a deadlock in the 1950s. Considering how difficult it was to reach an agreement on this issue, it is astonishing to see that the ICC Statute became substantive law a half-century after the adoption of the Genocide Convention. This phenomenon demonstrates the evolution in the environment and consciousness of the international community through time.