Since its first appearance in 1979, this work has established itself as a classic of legal philosophy. This study focuses on current jurisprudential debate between the "positivist" views of Herbert Hart and the "rights thesis" of Ronald Dworkin. MacCormick provides a critical analysis of the Dworkin position while also modifying Hart's. It stands firmly on its own as a contribution to an extensive literature. Now available in paperback, and with a new foreword by the author, this popular book will continue to be of use to students and teachers of law, legal theory, and philosophy.