Using an approach derived from sociological functionalism, this paper proposes a distinctive reconstruction both of the history of constitutionalism and of the changing form of constitutional law in global society. It argues that constitutional norms form adaptive principles for stabilising the inclusionary legal and political functions of society. Classical patterns of legal/political inclusion tended to rely on democratic forms of will formation (constituent power). Contemporary patterns of legal/political inclusion rely, in contrast, on rights. The shift in emphasis from constituent power to rights forms the constitutional foundation for the emerging global political system.proposed here, certain norms are indispensable for certain historical époques, and they are not, as for Luhmann, mere hyper-fictitious projections of inner-systemic communications. Nonetheless, the argument that public legal norms are generated, not through rational interpersonal deliberation, but within different social systems, has its origins in Luhmann's thought. The specific benefit derived from the use of a broadly Luhmannian approach is that it enables us to renounce the construction of constitutional norms as simply materialised principles, and we can penetrate the reflexive adaptive meanings contained beneath the literal surface of constitutional concepts. This in turn means that we can observe the societal pressures articulated through constitutional norms, and we can present a broad sociological analysis of the correlation between constitutional norms, changes in societal structure, and evolving societal demands for political power and law. In particular, this approach brings into view the role of concepts in stabilising societal structure, and it allows us to see the submerged functional meaning beneath the literal implications of normative claims. Overall, this approach creates a perspective in which we can interpret newly emergent expressions of constitutional normativity as part of deeper patterns of societal adaptation, in the context of embedded processes of systemic formation. In each respect, the paper proposes an encompassing theory of constitutionalism, both classical (national) and contemporary (global), as an account of the social construction of power, and it attempts to locate current analysis of global constitutionalism on more deeply reflected sociological foundations.4 On constituent power in the English revolution, see Pincus (2009, pp. 283−286). The classic expression of constituent power was formalised in revolutionary France