Subrogation means literally 'substitution'. The word is used in the context of English and Commonwealth law to denote a process by which one party is substituted to the position of another, that he may pursue that other's rights against a third party. This book seeks to rationalize the position of the doctrine of subrogation in the law of restitution. Within a systematic analytical framework, it gives a full account of the developing English and Commonwealth law of subrogation, and a selective use is also made of United States decisions. A number of false assumptions which have entered the case-law are exposed, and the principles upon which subrogation should be awarded are set on a regular basis. Subrogation is a remedy which can be awarded in many different contexts, and this definitive account will be useful not only to restitution lawyers, but also to academics and practitioners concerned with the law of property, family law, and commercial law (in particular, the law of insurance, bills of exchange, and principal and surety). This work provides a careful and thorough examination of the law of subrogation as it operates in English law today and as such it will be of invaluable assistance to all commercial lawyers.