Mapping Differentiated Integration
This chapter maps the development of differentiated integration over the entire history of the EU and across all member states and policies. It shows that differentiation has been on the rise in treaty law and legislation. Yet, relative to the dramatic growth in EU authority and member states over time, there is no evidence for a trend towards ‘ever looser union’. This chapter further shows that differentiated integration is mainly ‘multi-speed’. Most national opt-outs are temporary and end after a few years. However, there is evidence for ‘multi-tier’ integration, too. A small and stable periphery has formed driven by Denmark and the United Kingdom. While there is no sign of multi-menu integration, differentiation also has a policy dimension in that the integration and differentiation of core state powers shapes the evolving multi-tier structure of the EU. In contrast, the EU’s market and flanking policies constitute the domain of multi-speed integration.