A wind of change is blowing through the European judicial landscape. During the past decade, the European Union (EU) judiciary has undergone its biggest institutional overhaul in generations, the rise of authoritarian populism in Central and Eastern Europe has prompted a Rule of Law crisis, several supreme and constitutional courts challenged the supremacy of EU law, while the Court of Justice re-articulated the scope of the duty to refer under Article 267 TFEU and, for the first time, found that domestic last-instance courts breaching it triggered state liability. This Article argues that these and similar developments, once looked at together, suggest that something fundamental has shifted in the EU’s judicial architecture. A new form of judicial federalism has emerged, which departs from the traditional way in which relations between EU and Member State courts used to be structured. Although this new federalism is multifaceted and is marked by both centripetal and centrifugal forces, its distinguishing feature is a stronger centralisation, which manifests itself in a considerably expanded federal judiciary, a greater emphasis on hierarchy, a more careful use of European judicial resources, as well as tighter supervision of national procedures and court structures.

Forms of res judicata – Unwritten principle of EU law – National procedural autonomy v. EC supremacy – Revision of decisions v. state liability – Finality of administrative decisions v. judicial decisions – Higher respect for judicial decisions than for administrative decisions – Res judicata not absolute – ECJ itself under demands of legal certainty – Analogy between res judicata rules and rules of direct and indirect effect.