Foundations of Public Law offers an account of the formation of the discipline of public law with a view to identifying its essential character, explaining its particular modes of operation, and specifying its unique task. Building on the framework first outlined in The Idea of Public Law (OUP, 2003), the book conceives public law broadly as a type of law that comes into existence as a consequence of the secularization, rationalization, and positivization of the medieval idea of fundamental law. Formed as a result of the changes that give birth to the modern state, public law establishes the authority and legitimacy of modern governmental ordering.