The conventional wisdom holds that the president of the United States is weak, hobbled by the separation of powers and the short reach of his formal legal authority. In this first-ever in-depth study of executive orders, Kenneth Mayer deals a strong blow to this view. Taking civil rights and foreign policy as examples, he shows how presidents have used a key tool of executive power to wield their inherent legal authority and pursue policy without congressional interference.

Throughout the nation's life, executive orders have allowed presidents to make momentous, unilateral policy...