On the path to differentiation: upward transfer, logic of variation and sub-optimality in EU social policy
Upward transfer is one of the key concepts for understanding the dynamics of European integration (Jensen et al. 2014). However, upward transfer is often met with resistance, and more recent contributions to this literature particularly emphasize the importance of differentiation in European integration. Differentiated integration refers to cases in which ‘the territorial extension of European Union (EU) membership and EU rule validity are incongruent’ (Holzinger and Schimmelfennig 2012: 292), and it arises as a result of variation in the types and scopes of upward transfer in different member states and across policies. The conventional explanation is that greater heterogeneity among the member states and a broadened functional scope of EU regulation have caused differentiation to rise and to become increasingly visible across EU policies since the second half of the 1990s (Holzinger and Schimmelfennig 2012: 299; Leuffen et al. 2013: 21). This contribution examines the processes of upward transfer and differen-
tiated integration in the EU’s working time regulation as it has unfolded over time. It identifies the ‘opt-out’ as a means of differentiation that was adopted
structured as follows. The next section presents the theoretical framework, data and method. The third section conducts the analysis of EU working time regulation over time and identifies the causes, dynamics and effects of differentiation on the secondary legislation of EU social policy. The final section provides concluding remarks on the identified ‘path to differentiation’.