The European Court of Justice and legal European integration

This study examines the empirical implications of national and supranational signals for the separation of powers in legal European integration. The rulings of the European Court of Justice do not only resolve specific cases, but its dispositions also shape the scope of legal doctrine, requiring to anticipate the implications of rulings for future classifications of case facts by national courts. Drawing on data from the preliminary reference procedure, we estimate how the direction and strength of signals sent to the European Court of Justice shape the crafting of dispositions for legal European integration. Our findings show that strong supranational signals from the Commission and the Advocate General play a decisive role for crafting broad dispositions with clear thresholds for legal doctrine. Importantly, this influence holds regardless of the pro- or anti-integrationist direction, while signals from member states exert only a marginal impact for legal European integration.