United States v. Josef Altstoetter
International Military Tribunal
Control Council Law No. 10, at 954 (1948)
After World War II, the Allies created the International Military Tribunal to prosecute Nazi war criminals for crimes against peace, war crimes, and crimes against humanity. In one U.S. occupation-zone trial, fourteen individuals — including a member of the German high command, execution-squad leaders, doctors who ran medical experiments, and Nazi judges and prosecutors — were charged with war crimes and crimes against humanity. The defendants argued the charges violated ex post facto principles (nullum crimen sine lege), asserting these offenses weren't recognized international crimes under the IMT Charter when committed.
Whether the ex post facto rule applies to international law crimes in the same way it applies to domestic crimes.