Unjust Enrichment
A cause of action arising where the defendant has been enriched at the claimant's expense in circumstances that the law regards as unjust, and there is no defence. The four elements were set out in Banque Financière de la Cité v Parc (Battersea) [1999].
Independent editorial summary — not the official statute text. Read the official version on legislation.gov.uk.
Unjust enrichment is an independent area of English private law, distinct from contract and tort, concerned with reversing transfers of value that the law regards as unjustified. The UK Supreme Court has confirmed that the basic questions in any claim are the four-part test summarised by Lord Steyn in Banque Financière de la Cité v Parc (Battersea) Ltd [1999] 1 AC 221: has the defendant benefited or been enriched; was the enrichment at the expense of the claimant; was the enrichment unjust; and are there any defences. Each question must be answered in the claimant's favour before a remedy — commonly restitution of the value transferred — is available.
This four-question framework has been applied and refined in later Supreme Court decisions, including the Court's own discussion in Lowick Rose LLP v Swynson Ltd, which noted that the framework had been 'recently adopted by the Supreme Court' in Commissioners for Her Majesty's Revenue and Customs v The Investment Trust Companies (In Liquidation). Because the doctrine cuts across formal categories such as debt discharge and equitable subrogation, the courts have stressed that each of the four questions must be examined on its own terms rather than treated as a single, undifferentiated enquiry into fairness.
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Official sources
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