The establishment of the International Military Tribunal (IMT) and the International Military Tribunal of the Far East (IMTFE), respectively, in 1945 and 1946, evidences the problem of enforcing international criminal law without having an international criminal code or norms contained in positive international law.

The IMT charter and IMTFE statute provide for three crimes, namely, "crimes against peace," "war crimes," and "crimes against humanity." The first of these was not reflected in positive international law, the second was reflected in conventions embodying customary international law, and the third was an emerging international custom but without precedent in the practice of states. Furthermore, the charter and statute, as well as the jurisprudence, of these two tribunals brought about significant changes in the areas of immunity of heads of state, command responsibility, the defense of obedience to superior orders, and...