The Law of restitution has developed apace,taking its doctrinal starting point for the most part from the principle of unjust enrichment. This principle, however, has proved itself to be theoretically unstable, particularly in respect of the proper relationship of restitution with other bodies of law. This book is an account of the law of restitution which provides coherence in its relationships with other areas of private law, reflects a consistent theoretical underpinning, and offers an organisation of the law which is not solely dependant on theory but which also reflects a contextual coherence. One important consequence of this reformulation is that the subject matter which falls properly within the ambit of the law of restitution is considerably less than is currently supposed. Although directed to the substantive law of New Zealand, the book is an important contribution to the developing theatrical organisation of the law and extends far beyond that jurisdiction.