The responsibility of individuals and that of States under international law are generally regarded as independent systems. Each is a distinct form of responsibility governed by a different set of rules. The separability of these two forms of responsibility does not, however, dictate that they necessarily operate in isolation from one another. To the contrary, linkages between the fields of individual and State responsibility define the parameters of the principle of duality of responsibility in international law. Duality of Responsibility in International Law offers a roadmap to help navigate this complex legal space.