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.