Brexit and the Differentiated European (Dis)Integration

Abstract On 25 March 2017, the European Union celebrated the 60th anniversary of the Treaties of Rome, which established ‘an ever-closer union’ as a fundamental principle for European regional integration. Only four days later, the United Kingdom delivered an official letter triggering its withdrawal process from the Community. How could we comprehend Brexit integrative and disintegrative dynamics to the EU? The UK’s decision to leave the EU alongside recent crises in the Community and the spread of Eurosceptic movements fostered studies about disintegration dynamics. This article presents the current debate about differentiated (dis)integration based on up-to-date related literature. Next, it proposes a framework to assess the recent shifts in the UK-EU relationship and its contradictory effects on the EU project. The main argument of the paper is that the UK’s relationship with the European Union moved from an internal differentiated integration to a proposal of internal differentiated disintegration and, thereafter, to a process of external differentiated disintegration. Moreover, although Brexit means disintegration by one Member State, its effects on the EU project are mixed, initially promoting an integrative boom among the EU27 members, while at the same time neglecting disintegrating forces that could undermine the traditional European integration model.