Public International Law and Paradiplomacy

This chapter explores the evolving relationship between public international law, federalism, and the growing role of subnational governments in international relations. Traditionally, scholars in international law believe that the state is the only actor capable of producing public international law. However, in federal regimes, authority is constitutionally divided between central and subnational governments, creating legal and political complexities in international negotiations. Subnational governments, particularly in federal states like Canada, Belgium, and Germany, increasingly engage in international affairs across sectors such as trade, education, climate policy, and human rights. These governments often influence negotiations, implement treaties, and even lead initiatives, such as the Quebec–California carbon market agreement. The chapter distinguishes between two strategies used by subnational actors: intrastate channels (working with national governments) and extra-state channels (direct engagement with international organizations or foreign governments). Their ambiguous status—neither sovereign nor merely local—grants them flexibility to act in both spheres. The chapter highlights how subnational diplomacy challenges the traditional state-centric paradigm of international law, calling for a re-evaluation of legal norms. Examples such as Belgium's regional veto of the CETA trade deal and U.S. states’ international agreements show that subnational actors can shape, block, or implement international commitments. Despite lacking formal recognition in treaties like the Vienna Convention, their influence continues to grow, especially in global governance areas such as climate change. In sum, paradiplomacy is no longer a peripheral phenomenon but a significant force that reshapes how international law and diplomacy are practiced in multi-level governance systems.