The key to the growing prominence of prosecutors, both in the United States and elsewhere, lies in the prosecutor’s preeminent ability to bridge organizational and conceptual divides in criminal justice. Above all else, prosecutors are mediating figures, straddling the frontiers between adversarial and inquisitorial justice, between the police and the courts, and between law and discretion. By blurring these boundaries, prosecutors provide the criminal justice system with three different kinds of flexibility—ideological, institutional, and operational—and they strengthen their own hands in a legal culture that increasingly disfavors institutional rigidity and hard-and-fast commitments. At the same time, though, the mediating role of the prosecutor frustrates traditional strategies for holding government accountable. The bridges that prosecutors provide—between law and politics, rules and discretion, courts and police, advocacy and objectivity—make curtailing prosecutorial power and taming prosecutorial discretion trickier business than is often suggested, or at least a different kind of business.