This paper explores the nexus between enlargement and differentiated integration set against the background of past experiences and in view of the future of European integration. Although it considers convergence and not differentiated integration to be the underlying concept of enlargement, it also shows that the EU’s enlargement policy involves instruments which allow differentiated treatment. Analyzing the previous rounds of enlargement, the EU system appears to have been robust, coping with temporarily increased degrees of differentiation. However, the author argues against developing new forms of partial membership which would give outsiders a say in decision making. Elaborated types of association are instead advocated. Within the EU, differentiated integration remains the second best option and is not a panacea for better performance, legitimacy or holding the 27 together. In particular the leitmotif of a flexible Union would bear the risk of lengthy internal renegotiations with discontented countries over their terms of membership or even an unravelling of the EU altogether.
IAI EU60 paper, 2; February 2017, 15 p.