The debate about the power of the Court of Justice of the European Union (CJEU) has mainly focussed on the preferences, perceptions and strategic considerations of the High Judges in Luxemburg. This volume turns the analytical spotlight to another important determinant: the behaviour of actors with a stake in the policy conflicts resolved by the Court. Indeed, the CJEU’s influence depends, first, on being invited by stakeholders to intervene in the policy process through litigation and, second, on the correct implementation of its ruling by policy stakeholders. This book shows that actors’ propensity to litigate before the CJEU and their reactions to Court’s rulings are highly dependent on policy-specific actors’ constellations and governance structures. By focussing on how policy stakeholders and sector specific governance structures influence the Court’s impact, this introduction spells out what we call a ‘public policy approach’ to judicial power and summarizes the content and findings of the book.