The Dominican scholar John of Paris was one of the most controversial members of the University of Paris in the later Middle Ages. The author of over twenty works, he is best known today for On Royal and Papal Power, a tract traditionally linked to the explosive confrontation that took place between the French king Philip IV and Pope Boniface VIII in the early years of the fourteenth century. Although his role as a royal apologist has been questioned in recent years, John’s tract is often considered the first great defence of the independence of nation-states in the face of the claims to universal authority made by popes and emperors. Bringing together a team of international scholars with a wide range of expertise, this volume offers the first collection of essays in any language to be dedicated to an exploration of John’s thought. It re-examines his view of the relationship between Church and state, and his conception of political organization. It considers the role played by John’s background as a member of the Dominican order in shaping his ideas and breaks new ground in exploring the relationship between his various works, the origins of his thought, its development, and its legacy.