Foundations of Public Law offers a distinctive, provocative theory of public law, building on the views first outlined in The Idea of Public Law (OUP, 2003). The theory aims to identify the essential character of public law, explain its particular modes of operation, and specify its uniquetask. Public law is conceived 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 theauthority and legitimacy of modern governmental ordering.Public law today is a universal phenomenon, but its origins are European. Part I of the book examines the conditions of its formation, showing how much the concept borrowed from the refined debates of medieval jurists. Part II then examines the nature of public law. Drawing on a line of juristicinquiry that developed from the late-sixteenth to the early nineteenth centuries - extending from Bodin, Althusius, Lipsius, Grotius, Hobbes, Spinoza, Locke and Pufendorf to the later works of Montesquieu, Rousseau, Kant, Fichte, Smith and Hegel - it presents an account of public law as a specialtype of political reason.The remaining three Parts unpack the core elements of this concept: state, constitution, and government. By taking this broad approach to the subject, Professor Loughlin shows how, rather than being viewed as a limitation on power, law is better conceived as a means by which public power isgenerated. And by explaining the way that these core elements of state, constitution and government were shaped respectively by the technological, bourgeois, and disciplinary revolutions of the 16th-19th centuries, he reveals a concept of public law of considerable ambiguity, complexity andresilience.