International Law Duties Not to Recognize, Not to Assist, and to Cooperate Against Peremptory Norm (Jus Cogens) Violations
Peremptory norms (jus cogens) are the highest norms of international law. When these norms are violated, all States and international organizations have, at a minimum, three international legal duties to discharge while the violation is occurring: (1) the duty of non-recognition, where no State or international organization should recognize the situation caused by the violation; (2) the duty of non-assistance, where no State or international organization should render any aid or assistance to maintain this situation caused by the violation; and (3) the duty of cooperation, where all States and international organizations should cooperate to bring the violation to an end through lawful means. These international legal duties of non-recognition, non-assistance, and cooperation to end peremptory norms (jus cogens) violations through lawful means are particular consequences for third States and international organizations when such violations occur. Contrary to some misconceptions, these international legal duties do not comprise non-forcible third-party countermeasures, which are purposely designed by either an injured State or affected third party, at their discretion, to induce the State violator to return to compliance with international law. Rather, the international legal duties of non-recognition, non-assistance, and cooperation to end peremptory norm (jus cogens) violations operate as minimum safety valves for all States and international organizations to vindicate collective interests in the international system whenever any State violates the highest norms of international law. Unlike the right of injured States or affected third parties to impose countermeasures against a violating State which can be exercised at the legal discretion and political wherewithal of the injured State or affected third party, I argue that—as affirmed by the increasing jurisprudential practices of the International Court of Justice—it is already legally mandatory for all States and international organizations to discharge their respective international legal duties of non-recognition, non-assistance, and cooperation to end peremptory norm (jus cogens) violations. To this end, all States and international organizations should be conducting their respective legal audits that assess their utterances, conduct, acts, and measures in relation to situations caused by peremptory norm (jus cogens) violations. Saying nothing or doing nothing—whether through diplomatic silence or omission to act—will not suffice to discharge these duties that are triggered as a particular consequence of the collective impact of peremptory norm (jus cogens) violations on community interests1 in the international system.
Historically, these international legal duties are thinly elaborated in international jurisprudence, as well as rarely invoked by States and international organizations, due to the: (1) alleged interpretive indeterminacy of these international legal duties; (2) political and jurisdictional infeasibility due to continued sovereigntist emphasis on consent as an auto-limitation to international law; and (3) lack of prioritization of these international legal duties in diplomatic efforts as well as international and domestic law-making to address jus cogens violations in international law.2 I argue that these international legal duties are central to the lasting durability of the Charter-based international system’s collective purposes (e.g., to maintain peace and international security, ensure respect for equal rights and the self-determination of peoples, and to promote and encourage respect for human rights and fundamental freedoms without distinction), because these duties create minimum safety valve conditions for the exercise of collective State and international organization responsibilities in the international system to lawfully bring to an end jus cogens violations that cause injury and harm to all. Finally, I show that the trajectory of jurisprudence of international courts and arbitral tribunals draw more on their contentious and advisory jurisdiction to adjudicate reparations to give meaningful and enforceable content to the international legal duties of non-recognition, non-assistance, and cooperation to end jus cogens violations in international law, in a manner that could also be strategically emulated by national judiciaries around the world.
Recommended Citation: Diane A. Desierto, International Law Duties Not to Recognize, Not to Assist, and to Cooperate Against Peremptory Norm (Jus Cogens) Violations, 49 Fordham Int'l L.J. 397 (2026).