The idea of European union is as old as the European idea of the sovereign State.1 Yet the spectacular rise of the latter overshadowed the idea of European union for centuries. Within the twentieth century, two ruinous world wars and the social forces of globalization, however, discredited the idea of the sovereign State. The decline of the monadic State found expression in the spread of inter-state cooperation.2 The various efforts at European cooperation after the Second World War indeed formed part of a general transition from an international law of coexistence to an international law of cooperation.