Summary The doctrine of private international law and the doctrine of public international law rely on two supposedly self-standing theories whose independence is justified by the difference in their subject-matter: public international law mainly deals with relations between States and the international organizations they form, while private international law deals with relations between private individuals and corporations. However, each of these theories comes up against multiple paradoxes and unresolved problems that their specialists candidly acknowledge. The author argues that a unified and human-centered theory of international law promises to overcome such difficulties, to give a more accurate account of the contemporary law of international relations and to facilitate its further progress.