This book assesses the influence of the European Court of Justice (ECJ) on the governance of the EU, combining a close analysis of the case law with a wider law-in-context approach.It concentrates on the following themes: the function of the ECJ as the Supreme Court of the Union; judicial independence; the protection of the individual in the EU legal order; the relationship between the ECJ and the other branches of government at national and Union level and the relationship between the ECJ and the General Court, the European Court of Human Rights, and national courts. It goes on to consider the impact of the EU Reform Treaty on judicial protection and covers, among other topics including Union competence, direct effect, preliminary references, locus standi for individuals, a statistical analysis of judicial review and judicial activism.