Was the European Court of Justice a key actor in the "relaunching" of European integration in the 1980s? This article examines the crucial political role that was played by the Court with its Cassis de Dijon judgment in the rejuvenation EC harmonization policy and the development of the Single European Act. The authors challenge the dominant view that the Court's legal decisions in themselves create policy consequences, or that legal verdicts reflect the views of dominant member states, so as to create focal points around which a policy consensus emerges. They argue, instead, that the Cassis verdict acted as a catalyst, provoking a political response by the Commission, which attempted to capitalize on the verdict to create a "new approach to harmonization." This political entrepreneurship by the Commission triggered the mobilization of interest groups that lobbied their national governments for and against mutual recognition. Generalizing from the case, this article concludes that the Court performs three crucial roles in the EC policy-making process: opening political access to self-interested individuals, launching ideas into the policy-making arena, and provoking political responses through bold argumentation and unpopular verdicts.