What is liberty, as opposed to license, and why is it so important? When people pursue happiness, peace and prosperity whilst living in society, they confront pervasive problems of knowledge, interest, and power. These problems are dealt with by ensuring the liberty of the people to pursue their own ends, but addressing these problems also requires that liberty be structured by certain rights and procedures associated with the classical liberal conception of justice and the rule of law. In this work, Barnett examines the serious social problems that are addressed by liberty and the background or natural rights and procedures that distinguish liberty from license. He goes on to outline the constitutional framework that is needed to protect this structure of liberty. This discussion of the liberal conception of justice and the rule of law draws upon insights from philosophy, economics, political theory, and law. The book is intended to challenge specialists, and also be of value to both scholars and students working in a range of academic disciplines.