Until the advent of World War II, history had never witnessed the criminal conduct defined in Article 6(c) of the London Charter on such a scale. These crimes were unimaginably horrific to the international community. The law was, therefore, lagging behind the facts, and ultimately, the facts drove the law. Even though the facts superseded the law's anticipation, a general prohibition existed under the rubric of the “laws of humanity.” But its legal sufficiency raised questions of legality. International law had not been permeated with the values of human rights protection of individuals. The Law of the Charter laid the foundation of international criminal justice, which developed after the end of the Cold War, after which the international community developed the ICTY, the ICTR, the ICC, and the mixed-model tribunals. Whether the Charter was declarative of extant international law or innovative is now a moot point. However, the Charter's method is still relevant to contemporary processes that rely on the interplay between conventions, customs, and general principles of law, and whether the applicable law constitutes a legally sufficient source of ICL to satisfy the principles of legality.