Previous research has shown that European governments vary in their responsiveness to the demands of special interests benefiting from non-compliance with European Union law. However, what determines intra-member state variation and the persistence of violations? I argue that the political weight of interest groups can explain delays in changes from the non-compliant status quo to policies consistent with European legislation, and long and escalating infringement proceedings are the result of opportunistic governments maximizing political support by providing particularly influential special interests with continued non-compliance. This argument is empirically supported by an analysis of member states’ decisions to comply before infringement cases reach the Court of Justice of the European Union, the time-to-compliance from the initiation of official infringement proceedings, and the number of stages of these proceedings that a case reaches before finally being settled.