Blurring the borders between insiders and outsiders: Studying modes of partial (dis-)integration and their consequences on differentiated integration in the Eurozone and Schengen crises

Only recently, scholarship has started to study the effect of the so-called European polycrisis on differentiated integration (DI) in the EU. First studies suggest that while the degree of DI has increased significantly in some policy areas, boundaries between insiders and outsiders of integration have remained stable. EU member states have hardly changed their status. Our paper argues that this assumption is due to dichotomous classifications based on a legalist-institutionalist definition of DI. Accounting for modes of partial (dis-)integration, we conceptualize a gradual understanding of DI, allowing outsiders to gain insider qualities and vice versa. To substantiate our argument, we apply the proposed understanding to study DI during the Eurozone and the Schengen crisis. Our findings show that the distinction between insiders and outsiders has been more blurred than often assumed or claimed. During the Eurozone crisis, several euro outsiders have committed acts of partial integration going beyond their legal or political obligations. They opted into the European Banking Union, participated in the Fiscal Compact, and cooperated with euro insiders, such as in the financial assistance for Ireland. On the other hand, Schengen insiders have partially disintegrated during the Schengen crisis by systematically reintroducing internal border checks, not implementing the Common Relocation Scheme, and challenging the authority of supranational actors. These findings suggest a more nuanced understanding of DI, especially during and in the aftermath of European integration crises. Partial (dis-)integration allows insiders and outsiders to manage their status in a more flexible manner, weighing their domestic political constraints and relationships with other EU member states.