Class A war crimes

Class A war crimes are crimes against peace: planning, preparing, initiating, or waging a war of aggression under the postwar tribunals’ framework.

Crime against peace: An international crime involving the planning, preparation, initiation, or waging of aggressive war. This is the legal offense that defines the Class A category.
London Charter: The 1945 agreement that established the International Military Tribunal at Nuremberg and defined its crimes. It established the Nuremberg category of crimes against peace.
Class B war crimes: Conventional war crimes involving violations of the laws and customs of war. Class B addressed conduct in war, not the decision to wage aggressive war.
Tokyo Trial judgment: The 1948 judgment of the International Military Tribunal for the Far East in the trial of Japanese leaders. Its findings show how the Class A framework was applied to wartime decisions.
War of aggression: A war initiated through a state’s unlawful use of armed force against another state. Aggressive war is the central object of the offense.
Kellogg–Briand Pact: The 1928 treaty in which states renounced war as an instrument of national policy. Prosecutors relied on the pact as evidence that aggressive war was already unlawful.
Class C war crimes: Crimes against humanity, including murder, extermination, enslavement, and persecution of civilians. Class C focused on atrocities against populations rather than aggression between states.
Nuremberg principles: Principles formulated by the United Nations affirming individual responsibility for crimes under international law. They carried the postwar tribunals’ rejection of immunity for official acts into later law.
Common plan or conspiracy: An agreement among people to pursue a shared unlawful objective, sometimes treated as an international crime. The Tokyo Charter included conspiracy to wage aggressive war within Class A charges.
Stimson Doctrine: The United States policy of refusing to recognize territorial changes achieved through aggression. It reflected interwar opposition to conquest before the Class A trials.

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