Jus cogens is the ultimate source of international law. Differently from other forms of custom-ary laws, jus cogens underpins non-rebuttable norms overriding all contrary customary (with no peremptory status) and contractual laws. Yet, among the sources listed by art.38 of the Statute of the ICJ, there is no specifically identified category for jus cogens. The paper asks what is the nature of jus cogens and compare it with other available types of international norms. It sug-gests that jus cogens norms can be constituted as a specific sub-category among the already ex-isting sources of international law.
