World War II cost millions of lives and severely violated human dignity. As a lesson, the international community adopted the Universal Declaration of Human Rights (UDHR) in 1948 as a common principle to prevent future tragedies. René Cassin, a jurist and diplomat, coordinated the drafting process and inserted core ideas of “freedom, equality, and dignity” into the articles. By speaking for people suffering under colonialism and discrimination, he turned moral claims into a written document that could serve as a legal and ethical weapon. Although the UDHR is not legally binding, it inspired states to revise constitutions and laws and became the cornerstone of today’s system of international human rights law. Cassin’s work has had lasting influence on later movements such as women’s suffrage and the Convention on the Rights of Persons with Disabilities.

Having been wounded in World War I, René Cassin realized that civilians are the main victims of war and devoted his life to strengthening international law. As vice-chair of the UN Commission on Human Rights in 1946 he assisted Eleanor Roosevelt, drawing on natural-law theory and the 1789 French Declaration of the Rights of Man to design the UDHR. The drafting process had to bridge linguistic discrepancies and reconcile Islamic and Asian viewpoints; Cassin addressed this by structuring the text into a preamble, general principles, civil-political rights, and socio-economic rights. He introduced the notions of “bundles of rights” and “correlative duties,” arguing for the indivisibility of liberty rights and welfare rights—then a novel stance. Later, as a founding member of the Council of Europe, he contributed to the European Convention on Human Rights and helped institutionalize individual petitions against states, giving the document real enforcement mechanisms. The 1968 Nobel Peace Prize recognized not only his drafting but also decades of dissemination and educational work that turned abstract norms into operational protection systems. Cassin’s concepts are regarded as forerunners of modern developments such as the International Criminal Court and the principle of universal jurisdiction, which treat individuals as subjects of international law.

Cassin’s draft sought to transcend Kelsenian positivism by embedding natural-law values and a constitutional architecture into international norms. During Third Committee negotiations he re-organized the text into eight chapters and eighteen sections, creating a foedus-like structure that minimized cultural relativism. By placing “dignité inhérente” in the preamble and introducing a hierarchical ordering of articles, he foreshadowed the modern concept of jus cogens. His approach directly influenced the twin-covenant design of the 1966 International Human Rights Covenants and the individual-petition mechanism (Art. 34) of the ECHR. Drawing on jurisprudence of the French Conseil d’État, Cassin projected the single-fault doctrine of state responsibility into the international arena, anticipating hybridization between general international law and treaty-based human rights law. His collected lectures “La Pensée et l’Action” present a multi-layered integration model and are regarded as a starting point for post-1990s transnational constitutionalism. Cassin’s norm entrepreneurship remains a key case study for analysing the formation of customary international human rights law and is frequently cited within constructivist IR scholarship.