This book analyses the mechanics and the scope of the English law of proprietary restitution – at common law and in equity – and inquires whether and to what extent proprietary relief is available in defective transfers of property, such as mistaken payments. Drawing on an event-based classification of rights, it seeks to offer a coherent and rationalised approach to the transfer, creation and tracing of proprietary rights in this context.

The book is divided into six chapters. Chapter 1 sets out the foundations that are fundamental to understanding the law of proprietary restitution. After briefly outlining some basic concepts of property law, including ownership, property, title, interest and possession (section 2), the law of tracing and following will be explored (section 3), notably by examining the principles of the so-called “claiming exercise”. An elementary, taxonomical debate will then be conducted in the context of restitution, unjust enrichment, obligation and property (section 4). Refining the Birksian event-based analysis of rights, it will be argued that there is – alongside the categories of “consent”, “wrongs”, “unjust enrichment” and “miscellaneous other events” – a new, fifth category of events which may create restitutionary property rights, namely “property- related events”, such as substitution and mixture (section 4.3).

Chapter 2 shall offer a general introduction to the law of defective transfers of ownership, setting out the basic doctrinal framework at a somewhat abstract level. It will be observed, in particular, that it is inevitable to strictly distinguish between three different levels at which any particular kind of defect, such as a mistake, might operate, namely property, contract and unjust enrichment.

The proprietary consequences of defective transfers of ownership are best analysed by asking the following five questions: (i) Has legal ownership passed to the transferee or has it been retained by the transferor ab initio (the proprietary transfer being void at common law)? (ii) Has beneficial (i.e. equitable) ownership passed to the transferee or has it been retained by the transferor ab initio (the proprietary transfer being void in equity)? (iii) Does the law of property (common law) impose a legal power in rem to revest legal ownership (the proprietary transfer being voidable at law)?