Jus Cogens: Peremptory Norms
The hierarchy of international law and the supreme norms that no state can violate or contract out of.
The Highest Law
International law has a hierarchy, and at the top sit jus cogens (also called peremptory norms). Article 53 of the Vienna Convention on the Law of Treaties defines jus cogens as 'a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character.'
In practical terms, jus cogens norms override everything else. Any treaty that conflicts with a jus cogens norm is void. No state can agree to violate these norms, even voluntarily. They represent the fundamental values of the international community that cannot be bargained away. This is a radical concept in a legal system traditionally built on state consent: jus cogens says there are certain things states simply cannot agree to do.