This article seeks to remedy a fundamental flaw in the debate about European integration and European Union (EU) law: the almost complete absence of a reckoning with the legacy of empire and imperialism. The article shows that the significance of EU law can be understood only against the background of the historical transformation of the European public law order with the decline of the European empires. European integration is an integral part of a new European public law order that finally replaced the public law order of the European empires – Droit Public de l’Europe or Jus Publicum Europaeum – in which the European states held a privileged place as the only ‘civilised’, and hence, sovereign states in the world. The post-World War II European public law order entailed a new vision for domestic public law, but also constituted intra-European relations anew, and established a new set of external relations between Europe and its former colonies. With the shift from ‘European’ international law to ‘universal’ international law in the twentieth century, European integration helped carve out a space for ‘Europe’ in a world where Europe was no longer the centre of gravity.

This Article uncovers the normative political theory underlying the legal doctrine of constitutional pluralism, as it is used in the EU today. Constitutional pluralism, once described as a semi-official legal doctrine in the EU, is now being used by some member states to challenge its authority and rules. By reconstructing the political thought of one of its founders, N. MacCormick, this Article takes issue with two most common interpretations of constitutional pluralism: On the one hand, it has been claimed that the normative political content of constitutional pluralism is virtually identical, or at least compatible, with that of Kantian rights-based cosmopolitanism; on the other, it has been contended, especially with regard to its uses in Hungary and Poland, that it was an inherently dangerous, illiberal, normative theory. This Article offers to move away from current legal debates to go back to the origins of constitutional pluralism. It argues that constitutional pluralism is not a purely liberal theory indeed. But neither is it inherently illiberal. Rather, both liberal and illiberal readings are possible, but partial, interpretations of MacCormickian constitutional pluralism. A more systematic interpretation shows that constitutional pluralism opens a path to move beyond this somewhat archetypical divide.

To the extent that the UK's decision to withdraw from the EU can be interpreted as a reassertion of the classic ideas of Westphalian sovereign statehood, it questions the relevance of constitutional pluralism as a resolutely ‘post-sovereign’ model of relations between state administrations and their supranational counterparts. This contribution will therefore examine the usefulness and relevance of the idea of constitutional pluralism after Brexit. It looks at the various features and relationships affected by the Brexit process analysing the relevance of constitutional pluralism to each relationship pre- and post-Brexit, concluding that, whereas Brexit clearly affects the different relationships involved, constitutional pluralism can and will remain relevant to EU/UK relations as well as within the EU, well into the future.

Constitutional pluralism is a theory for the post-sovereign European state. This only makes sense historically, emerging out of postwar European reconstruction through the repression of popular sovereignty and restraining of democracy, including through the project of European integration. It became unsettled at Maastricht and evolved from a series of irritants into a full-blown crisis in the recent decade, with sovereignty claims returning both from the bottom-up and the top-down, to the extent that we can legitimately ask whether we are now moving ‘beyond the post-sovereign state’? Constitutional pluralist literature fails to capture this in that evades material issues of democracy and political economy.