Linking claimant and defendant in the law of unjust enrichment

Professor Duncan Sheehan presents a working paper examining the different attributive techniques that the law of unjust enrichment employs to link the claimant and the defendant together.


All unjust enrichment claims in English law require to meet a number of probanda. The defendant must be enriched, must be enriched “at the expense of” the claimant, and there must be an unjust factor. A lot of ink has been spilled on the causes of action, but “at the expense of” remains relatively under-theorised, and was under-explained by the Supreme Court in Bank of Cyprus v Menelaou [2015] UKSC 66. Three interrelated questions arise concerning “at the expense of.” The first is whether the claimant and the defendant are linked at all, a question sometimes put in terms of whether the defendant was enriched directly from the claimant. The second is whether the link is too remote and the third whether the gain and loss must be equivalent, or whether it matters if the claimant has “passed on” the loss.

The paper examines the different attributive techniques that the law employs to link the claimant and the defendant together. As such it is concerned with the first question above. Although not universally accepted the main techniques seem to be causation and tracing, and even authors like Eli Ball who deny that tracing is a part of unjust enrichment accept the relevance that tracing has in cases like Relfo v Varsani [2014] EWCA Civ 360. The relationship between these two techniques and their limits, such as the suggested direct connection requirement is therefore difficult and controversial, and the paper attempts to unpick the relationship between them and the links with enrichment by value and enrichment by rights.

About the Speaker

Duncan Sheehan is Professor of Business Law at the University of Leeds, School of Law. His research expertise covers the areas of trusts and personal property law, especially secured transactions law. His work on the law of unjust enrichment examines many of the issues from a comparative perspective, looking particularly at the mixed jurisdictions: Scotland and South Africa. In addition to a wide interest in private law theory his work examines the underlying philosophical rationale for the law of unjust enrichment and specific unjust factors, with an especial recent interest in the application of the philosophy of action to the law.

Professor Sheehan joined the Law School in 2016 from the University of East Anglia. He completed his doctorate at Oxford University on payments by mistake of law under the supervision of the late Professor Birks. He is currently the School’s Postgraduate Research Tutor and a member of the Senior Management Team.

Professor Sheehan is a member of the Society of Legal Scholars Executive Committee, a member of the Secured Transactions Law Reform Project, and an academic member of the Chancery Bar Association. He sits on Advisory Groups to respectively the Law Commission’s Bills of Sale Project and to the City of London Law Society’s Secured Transactions Code Project. He served on the AHRC Peer Review College between 2014 and December 2017. He was a Distinguished Visiting Fellow at the TC Beirne School of Law, University of Queensland in March and April 2014.

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