How differentiated integration shapes the constraining dissensus

Abstract

ABSTRACT If European Union (EU) member states realise differentiations in EU Treaties, what effect do we see on public and political support for future integration? We argue on the basis of a two-tier integration theory and postfunctionalism that differentiations of member states do lead to a preference for slower future integration by its citizens and parties. Once citizens and parties are used to opting out, they demand more of the same in the future. We test our arguments with time-series cross-sectional data for 1994–2018 on all voluntary primary law opt-outs in the EU. Our panel matching estimates demonstrate that opt-outs decrease integration support. After a differentiation, parties become more Eurosceptic on average and publics express a lower preference for future integration. This suggests that differentiated integration is not a cure against Euroscepticism that leads to a unified EU in the future but rather reinforces two-tier integration.