De facto differentiation in the European Union - Circumventing rules, law, and rule of law

Abstract

Differentiation has become a common feature in European integration and attracts considerable scholarly attention. The vast majority of academic literature focuses on formal (de jure) differentiation, in which opt-outs or other derogations are codified in EU law. This chapter elaborates on the as yet understudied and ill-defined phenomenon of informal (de facto) differentiation which is not recognised or supported by EU law. Combining knowledge from several disciplines of EU studies, this chapter conceptualises de facto differentiation and distinguishes three distinct types: de facto differentiation by non-compliance, cooperation outside the EU legal framework, and unilateral opt-ins to the acquis. These theoretical foundations are subsequently discussed in an illustrative study of three cases in Economic and Monetary Union, comprising all three types of de facto differentiation. Ultimately, the contribution of this chapter is a conceptual framework of de facto differentiation that invites further research in this area.