Certain activities in war that violate the established rules of warfare, as set out in the Hague and Geneva Conventions. In most societies, such activities as the killing of prisoners, their torture or enslavement, hostage‐taking, and the deportation and killing of civilians are deemed to be war crimes. Present‐day attitudes to war crimes have been influenced by the trials at Nuremberg and Tokyo in 1945–46 of German and Japanese wartime leaders. In the course of these proceedings, it was made clear that an individual was to be held responsible for his or her actions even if carrying out the orders of a higher authority. During the Vietnam War (1964–75), US soldiers were indicted on charges of killing civilians; and Iraq’s hostage‐taking and maltreatment of prisoners during its occupation of Kuwait (1990–91) also led to calls for those responsible to be tried for war crimes. A war crimes tribunal of the International Court of Justice, the principal judicial organ of the United Nations, was convened in 1993 to try people accused of ‘ethnic cleansing’ during the conflict in Bosnia and Herzegovina. Several successful prosecutions followed. In 1999 this tribunal indicted the Yugoslav president, Slobodan Milošević, of war crimes; his trial began in 2002 but was not completed before he died (2006). The trial of Radovan Karadžić, leader of the Bosnian Serbs, began in 2009, ending in 2016 with Karadžić sentenced to 40 years in prison having been found guilty of genocide, multiple counts of war crimes and crimes against humanity. A similar tribunal was established in 1994 to prosecute those responsible for the genocide in Rwanda.