Sharing Sovereignty in the EU’s Area of Freedom, Securityand Justice

European integration has turned the EU neither into a state, in which authority is fully centralized in Brussels, nor is the EU a classic international organization, in which member states remain fully sovereign. Instead, European integration is patchy. For some policies, decision-making authority still rests with the member states whereas, for others, policy-making authority was transferred to the EU. Why does the EU’s authority vary across policies? Taking policies belonging to the EU’s Area of Freedom, Security and Justice as a sample, Stefan Jagdhuber theorizes and empirically analyzes why integration proceeded on illegal immigration policy and judicial cooperation on civil law matters whereas it stagnated for legal immigration policy and judicial cooperation on criminal law matters. The findings show that uneven integration trajectories in the EU are likely when policy interdependence, supranational activism and domestic constraints differ across policies.