There is an impressive body of legal literature on the relationship between the European Court of Justice (ECJ) and its various 'interlocutors' (EU institutions, national jurisdictions, EU interest groups, multinationals, etc.) There has also been occasional speculation at various points in time as to whether or not the ECJ was guilty of 'judicial activism.' Recently however, the ECJ has come under heavy attack from various sides. It has been criticized by leading politicians, national judges, and legal academics for unduly extending the scope of EU law and overstepping its own jurisdiction, to the detriment of the reserved competences or (more broadly) the political autonomy of the Member States. This volume addresses the issue by collecting and confronting the views of leading specialists of EU law, examining the ECJ's recent role in relation to the following five major areas of contention: the general role of the ECJ in defining the scope of EU law in relation to national law * citizenship and migration * fundamental rights and anti-discrimination * internal market * institutional autonomy (rights, remedies, procedures, and sanctions).