This title was first published in 2001. In the Western legal tradition, the history of restitution for unjust enrichment reaches back to pre-classical Roman law. In common law, the roots of unjust enrichment may be said to lie in the fourteenth century; but its history as a subject of academic study is much shorter. The law of restitution has become increasingly important in the courts of the common law world during the last decade. This has generated a great deal of scholarly attention and there has been an explosion of literature as legal academics have addressed the theoretical foundations of the subject, its structure and its underlying principles. This volume collects the most important elements of that literature, organized thematically, to show how the subject is developing and where it is likely to go in the future.