Conclusion
This chapter evaluates the implications of differentiated integration for the legal order, democratic quality, degree of solidarity, and further development of European integration. The chapter argues that eschewing differentiation would entail serious opportunity costs for the EU. Forgoing differentiation and limiting European integration to a clear choice between ‘in’ and ‘out’ would most likely result in a lower level and regional as well as functional scope of European integration, providing fewer opportunities for democratic community formation, more limitations to democratic choice, and less European solidarity than differentiated integration does. As regards the further development of European integration, differentiation is likely to prove useful in getting new policy domains ‘off the ground’, but less relevant for the further consolidation and deepening of already highly integrated policies. In these areas, the academic and policy debate is likely to focus increasingly on the governance and implications of differentiated integration.