Unjust Enrichment and Equity

Abstract

This chapter addresses the complex relationship between unjust enrichment and equity. It examines their theoretical relationship to one another as categories, the role of ideas of conscience, unconscionability and ‘unconscientious retention’ as the drivers of claims within unjust enrichment law, and a number of sites of conflict and tension between rules developed at common law and in equity in cases involving mistake, the receipt of misdirected assets and tracing rules. In seeking to bring coherence and better understanding to the relationship between equity and unjust enrichment in the era after the High Court of Australia decision in Australian Financial Services and Leasing Pty Ltd v Hills Industries Ltd [2014] HCA 14, (2014) 253 CLR 560, the chapter highlights key questions about the proper role of fault within the modern law, and points to the danger of assimilating all claims falling within the unjust enrichment category in ways that potentially blind one to differences in their underlying logic and the context in which they were developed. In particular, it considers the equitable doctrines of undue influence, knowing receipt, mistaken gifts and tracing and the extent to which ‘unjust enrichment’ provides a useful taxonomical label or unifying legal principle in these examples.