Abstract
The English law of unjust, or unjustified, enrichment is part of the civil law of obligations, which comprises also the law of contract and the law of torts. A claim based upon the recipient’s enrichment requires that the defendant be benefited at the expenses of the claimant and that the transfer of wealth from the claimant to the defendant be tainted by an unjust factor. A claim in unjust enrichment aims to achieve restitution of the defendant’s gain, whereas a claim in tort redresses the loss of the claimant. Unlike tort law, the wrongfulness of the defendant’s behaviour is not a requisite of the cause of action in unjust enrichment. In this paper, enrichment claims will be examined from the perspective of a theory which considers the law of enrichment in historical and comparative perspective. In applying this theory, I will argue that, in many European legal systems, civil claims which target the defendant qua enriched, as opposed to wrongdoer or contractual party, show a tendency to follow two main patterns. They are prone to lean either towards a strict legal principle or towards a more lenient approach linked to a principle of justice. Accordingly, it has been submitted that the qualification of the enrichment reflects this partition: ‘unjustified’ enrichment claims display different characteristics and a different application radius in comparison with claims which are triggered by an ‘unjust’ enrichment. This view has been advanced and defended elsewhere. Its precepts will be only summarised here to set the framework for its application to a decision of the House of Lords, Sempra Metals v. Inland Revenue Commissioners, which raises the question of the position taken by English law within this European trend. After a brief exposition of the account which distinguishes the concepts of ‘unjust’ and ‘unjustified’ enrichment, I shall consider some questions which emerge from the analysis of the judicial opinions in Sempra. I shall argue that Sempra raises structural issues similar to those which characterise civil law developments in this area. Their Lordships’ opinions reveal a certain degree of consistency between English law and the dual-pillar approach which, it is suggested, is a recurrent, albeit unstated, character in the law of enrichment of civilian systems. As the historical development of civil law models indicates, the polarisation of the legal actions is likely to be due to a tension between the clarity and relative strictness of the claim in unjustified enrichment on the one hand and the flexibility of the claim in unjust enrichment on the other hand. This tension between the two claims is to be welcomed since it sharpens the remedial tools at the court’s disposal to nullify the consequences of misplacements of wealth. This paper is not intended as an essay on Sempra even though this judicial decision is central to it. As such, no attempt will be made to engage with all the issues raised by the Law Lords nor will the main theoretical accounts of unjust enrichment linked to this case be reviewed. Rather, the Sempra case will be used as a means by which the theory distinguishing unjust and unjustified transfers of wealth, and in particular its practical significance, will be tested. Since the essay is not primarily targeted at Roman lawyers, the analysis of Roman law will be kept to a minimum.