The emergence in the Commonwealth of what is now known as the law of restitution has had a rapid and significant effect on developments in large portions of the private common law. It is sometimes difficult to believe that in the space of a little more than 30 years the internal structure of the private common law has fundamentally transformed. The private law of obligations is no longer contained in the neat division between contract and tort that was for generations the staple diet of lawyers. Present and future generations of lawyers must cope with a more densely textured, and increasingly flexible, categorisation within which the law of restitution must be properly accommodated. The object of this book is to enable practitioners and students to gain a full understanding of the law of restitution and its place in the wider law of civil obligations.