Jus cogens

A peremptory norm (also called jus cogens or ius cogens /ˌdʒʌs ˈkoʊdʒɛnz/ or /ˌjʌs/;Latin for "compelling law") is a fundamental principle of international law that is accepted by the international community of states as a norm from which no derogation is permitted.

There is no universal agreement regarding precisely which norms are jus cogens nor how a norm reaches that status, but it is generally accepted that jus cogens includes the prohibition of genocide, maritime piracy, slaving in general (to include slavery as well as the slave trade), torture, refoulement and wars of aggression and territorial aggrandizement. Recent scholarship has also proposed the idea of regional jus cogens.

Unlike ordinary customary law, which has traditionally required consent and allows the alteration of its obligations between states through treaties, peremptory norms cannot be violated by any state "through international treaties or local or special customs or even general customary rules not endowed with the same normative force".

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