Authority transfer and governmental legal contestation before the court of justice of the EU

Abstract Over the course of European integration, European Union (EU) institutions have gained increasing authority – but since the 1990s, this process has triggered backlash from Member State governments and citizens. We examine whether this transfer of authority has also led to greater legal contestation in cases before the Court of Justice of the EU involving Member States. Drawing on original data covering all amicus briefs in direct actions with government parties from 1954 to 2022, we find growing mobilization against EU legislation, implementation, and enforcement. While challenges to legislation became more salient without becoming more polarized, litigation over implementation decisions grew more controversial yet remained low-profile. Meanwhile, the Commission’s enforcement of EU law has faced mounting intergovernmental pushback, leading to greater restraint on the side of the Commission. These partly diverging trends reflect uneven shifts in the EU’s authority to legislate, implement, and enforce binding rules.