The Nuremberg Principles were pronounced at the request of the General Assembly of the UN by the International Law Commission and adopted in a unanimous resolution in 1950. Thereafter these became rules of Customary International Law.
The Nuremberg Tribunal was conducted under a Charter which defined as a crime under international law, "planning, preparation, initiation or waging of a war of aggression, or a war in violation of international treaties, agreements or assurances or participation in a common plan or conspiracy for the accomplishment of any of the foregoing."4
The Charter for the Nuremberg trials defined and the Judgment affirmed a number of other principles, such as Crimes against Peace, Crimes against Humanity, War Crimes and personal criminal responsibilities for the commission thereof.
A copy of the Nuremberg Principles is annexed here as Appendix A.
4 Article 6 of the Charter annexed to the Agreement establishing the Tribunal for the trial of War Criminals.