The introductory part consists of defining constitutional imaginaries as internal symbolic constructs of self-constituted positive law and politics which make it possible to imagine and describe functionally differentiated modern society as one polity and distinguish between legal and political legitimacies and illegitimacies in this polity. Imaginaries, therefore, are not limited by the unity of topos-ethnos-nomos and evolve in national as well as supranational and transnational constitutions. In the context of European constitutionalism, general imaginaries of the common market, universal rights and democratic power are thus accompanied by specific imaginaries of European integration through legal pluralism, administrative rationality of calculemus, economic prosperity and democratically mobilised non-state community. These imaginaries invite constitutional theorists to rethink the juridical concept of constitution and employ sociological social theoretical perspectives of constitutionalism within and beyond the state. Furthermore, they show that political constitutions of the autopoietically operating systems of positive law and politics include a poietic societal force impossible to contain by legal norms and political institutions.