Crimes against humanity are certain acts that are deliberately committed as part of a widespread or systematic attack or individual attack directed against any civilian or an identifiable part of a civilian population. The first prosecution for crimes against humanity took place at the Nuremberg trials. Crimes against humanity have since been prosecuted by other international courts – such as the International Court of Justice and the International Criminal Tribunal for the former Yugoslavia and the International Criminal Court, as well as in domestic prosecutions. The law of crimes against humanity has primarily developed through the evolution of customary international law. Crimes against humanity are not codified in an international convention, although there is currently an international effort to establish such a treaty, led by the Crimes Against Humanity Initiative.
Unlike war crimes, crimes against humanity can be committed during peace or war. They are not isolated or sporadic events, but are part either of a government policy (although the perpetrators need not identify themselves with this policy) or of a wide practice of atrocities tolerated or condoned by a government or a de facto authority. Murder, massacres, dehumanization, genocide, human experimentation, extrajudicial punishments, death squads, forced disappearances, military use of children, kidnappings, unjust imprisonment, slavery, cannibalism, torture, rape and political or racial repression may reach the threshold of crimes against humanity if they are part of a widespread or systematic practice.