Introduction—(Re)defining Membership? Current and Future Perspectives for EU Differentiated Integration

This chapter sets the background and the analytical framework for this edited volume, which aims at: (a) (re)defining membership in today’s EU and (b) at drawing a balance on the state of differentiated integration, while examining how it could and should continue to evolve in the future. Indeed, while EU membership could, at first sight, appear to be a straightforward concept to defined (art. 2 Treaty on Europpean Union), a closer examination reveals a myriad of nuances. Some EU states do not (fully) participate in all EU policies, while non-EU states sometimes participate in (some) EU policies indeed. Therefore, both internal and external differentiation exists within the EU and in its relationship to third states. Based on the analyses presented by the various contributors to this edited volume, it is posited that EU membership, though possibly a fuzzy concept if considered from a non-strictly legal perspective, still clearly differentiates Member States from third states. It is, however, contended that the EU may need to distinguish between full and associate members in the future, especially if new states join in the near future.