(please note, much of the following is a simple cut and paste from the one site….
Nuremberg Trials: Genocide and Crimes Against Humanity. I acknowledge the input of this article to my post)
The Nuremberg trials of 1945 and 1946 influenced later developments of international law and the courts that enforce it. It underpinned the work of the Tokyo War Crimes Trials (1946–1948) and subsequent trials under Control Council Law No. 10 in occupied Germany. They also firmly established the basis for attributing individual criminal responsibility for atrocity crimes such as genocide, serious war crimes, and crimes against humanity that would constitute the core jurisdiction of international criminal tribunals at the end of the twentieth century and beyond. The trials accelerated the further development of the principles of international criminal law and international humanitarian law, as reflected in the Genocide Convention of 1948, the Geneva Conventions of 1949, the Geneva Protocols of 1977, the Statutes of the International Criminal Tribunals for the Former Yugoslavia and for Rwanda, and the 1998 Rome Statute of the International Criminal Court.
The UN General Assembly affirmed in Resolution 95(I) of December 11, 1946, the "Principles of International Law Recognized by the Charter of the Nuremberg Tribunal." The illegality of aggression was further elaborated in a 1974 UN General Assembly resolution defining aggression with regard to state responsibility, and in the Draft Code of Crimes Against the Peace and Security of Mankind, which was adopted by the International Law Commission. Deeply influenced by the record of the Nuremberg trials, the states that are party to the Rome Statute of the International Criminal Court continue to negotiate how to activate the crime of aggression which, for purposes of individual criminal responsibility, is included in the new court's jurisdiction. In Justice Jackson's opening statement at the Nuremberg trials, he summed up what they were all about:
The wrongs which we seek to condemn and punish have been so calculated, so malignant, and so devastating, that civilization cannot tolerate their being ignored, because it cannot survive their being repeated. That four great nations, flushed with victory and stung with injury, stay the hand of vengeance and voluntarily submit their captive enemies to the judgment of the law is one of the most significant tributes that Power has ever paid to reason.
The London Charter required a fair trial for all of the defendants, and set forth fundamental rules for that purpose. These rules included the right to counsel and the right to cross-examine any witness. As the trials got underway, however, defense lawyers often found it difficult to obtain documents sought for the defense of their clients, and delays in the translation of key documents created difficulties for both the prosecution and defense.
The indictment, issued on October 19, 1945, included four charges drawn from the London Charter: a common conspiracy to wage aggressive war, crimes against peace, war crimes, and crimes against humanity. The second category, crimes against peace, had no pre-existing definition in international law. It was defined in the London Charter as the "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 [war crimes or crimes against humanity]."
The third category, war crimes, was a well-established concept in international law. It was defined in the London Charter as follows:
violations of the laws or customs of war. Such violations shall include, but not be limited to, murder, ill-treatment or deportation to slave labor or for any other purpose of civilian population of or in occupied territory, murder or ill-treatment of prisoners of war or persons on the seas, killing of hostages, plunder of public or private property, wanton destruction of cities, towns or villages, or devastation not justified by military necessity.
The fourth category, crimes against humanity, had at best a very problematic foundation in international law. Such crimes were defined as follows:
murder, extermination, enslavement, deportation, and other inhumane acts committed against any civilian population, before or during the war; or persecutions on political, racial or religious grounds in execution of or in connection with any crime within the jurisdiction of the Tribunal, whether or not in violation of the domestic law of the country where perpetrated.
Fundamentally, the allies themselves escaped being brought to trial on any counts, because a pre-condition in the formation of the IMT was the need to establish whether the nation state was guilty of a war of aggression. This also explains why the leadership of the minor axis powers were not brought to account at Nurnberg. Subsequent tribunals such as the Hague International criminal court of justice operate under different rules, and it would be possible to prosecute the allies for war crimes for some of their activities.
The basic rules of evidence, and the legal procedures used in the IMT at Nurnberg were mostly Anglo American in character. This basic principle has continued into the post Nurnberg permutations of the IMT. It means there is a heavier burden of proof for the prosecution, and this has meant many of the more recent trials are long drawn out affairs, with a great deal of uncertainty as to the outcomes
I will see what I can unearth about the terms of reference for the Tokyo war crimes tribunal, which did not have the same terms of reference in its formation to the Nurnberg tribunal.