The European Court of Justice, and courts in general, were key actors in the creation of the European Union (EU). However, they cannot change major policy without political supporters to lobby and litigate for implementation. We argue that part of the resolution of this apparent paradox comes from complementing existing work on the activities of EU courts and litigants with a focus on a third actor: implementing bureaucracies, whose effect on law and politics has not been a focus of studies of EU legal development. Their calculations about whether to pay attention, lobby, and comply shape the impact of the law. Those calculations are variable and patterned; when and how bureaucracies listen to courts varies in predictable ways. We find evidence for this proposition in the case of EU health care services law, both in the secondary literature and in empirical studies of France and Spain.