The Conceptual Boundaries of Unjust Enrichment

Abstract

The law of unjust enrichment has matured into a distinct and influential branch of private law, yet persistent uncertainty remains concerning its conceptual boundaries and relationship with neighbouring doctrines such as contract, tort, equity, and property. This article undertakes a systematic examination of the limits of unjust enrichment as an autonomous cause of action, focusing on the core elements of enrichment, at the expense of the claimant, unjust factors (or absence of basis), and available defences. The analysis interrogates whether contemporary judicial reasoning has expanded unjust enrichment beyond principled coherence, particularly in complex multi-party and commercial contexts. Drawing upon leading common law authorities and comparative materials from Canada, Australia, and mixed legal systems, the article argues that conceptual overreach risks diluting the analytical clarity that has been central to the subject’s development since the late twentieth century. At the same time, an overly restrictive conception may fail to respond adequately to novel forms of enrichment arising in modern financial and commercial transactions. The article proposes a structured framework for identifying legitimate unjust enrichment claims, emphasising the need to maintain doctrinal discipline while accommodating incremental evolution. By distinguishing unjust enrichment from compensatory and restitutionary responses to wrongdoing, the article seeks to clarify the proper role of unjust enrichment within private law and to contribute to ongoing debates regarding its future trajectory.