Governing Differentiation and Integration in the European Union: Patterns, Effectiveness and Legitimacy

We present here the key theoretical underpinnings and general approach of the Special Issue “Governing Differentiation and Integration in the European Union: Patterns, Effectiveness and Legitimacy”, which collects contributions of a group of experts and scholars from the Horizon 2020 EU IDEA – Integration and Differentiation for Effectiveness and Accountability project. The key concepts for the analysis are clarified, namely differentiation, differentiated integration, effectiveness, legitimacy and sustainability. The basic claim of the Special Issue is that differentiation is not only necessary to address current challenges more effectively by making the Union more resilient and responsive to citizens. By introducing a useful degree of flexibility in the complex EU machinery, differentiation is also desirable, so long as such flexibility is compatible with the core principles of EU constitutionalism and identity, sustainable in terms of governance and acceptable to EU citizens, member states and affected third partners.
Keywords: differentiation; differentiated integration; effectiveness; legitimacy; sustainability