Doctrine at the intersection between international humanitarian law and international criminal law has long averred the principle of universal jurisdiction at customary international law over war crimes committed by enemy prisoners of war before capture. Contemporary treaty rules since 1945 have reaffirmed such a jurisdiction in the lex scripta, and there are examples of the prosecution of enemy war criminals under universal jurisdiction after various conflicts up to the present day. This article investigates the use of military courts to prosecute enemy prisoners during wartime and, through a selection of cases from various jurisdictions, asserts that the jurisdiction actually claimed in national laws in such cases generally does not concern war crimes and does not rely on universal jurisdiction as its international law basis.