Ius Cogens (peremptory international law) is a contradiction in itself! According to the classical understanding of international law, all states are equal and sovereign - without the consent of a state, it cannot be bound to anything. Nevertheless, there have been peremptory norms of international law for some time now that obligate states even against their will. Through judgments from international courts, conventions, and a large portion of the literature on the subject, the author explores how this self-contradiction can be understood and whether Ius Cogens can contribute to the stabilization of international relations and international law. The conclusion reached is that Ius Cogens protects the moral values of the international community (e.g., human rights and the prohibition of violence) and thus has a stabilizing effect.