An inquiry into the philosophical foundations of the defendant's duty of restitution in unjust enrichment

The aim of this thesis is to uncover the philosophical foundations of the defendant's duty of restitution in the law of unjust enrichment. I argue that the current dominant account for the duty of restitution – that it is best explained by the model of corrective justice – is inadequate as it fails to accommodate two key features of an action in unjust enrichment, namely, the irrelevance of fault and the absence of causation. In place of corrective justice, I suggest three alternative models: distributive justice, equity, and commutative justice. The first two candidates ultimately prove unsatisfactory, but in their respective failures help identify certain fundamental elements of unjust enrichment. The third is the most promising, but care must be taken not to conflate it with corrective justice. I argue that corrective and commutative justice are not synonymous since, while corrective justice exemplifies an intrapersonal equality, the relevant form of equality for commutative justice is interpersonal. I define commutative justice as exemplifying the principle of equality in exchange, specifically, equality of the things exchanged. Unjust enrichment, I conclude, is a manifestation of inequality of exchange, of commutative injustice. Although commutative justice accurately describes situations of unjust enrichment, I admit that it cannot alone justify the existence or imposition of the duty of restitution on the defendant. Something more is required: a normative theory for preserving the status quo of initial entitlement distribution. As such, I canvas two alternative theories as exemplified by Hegelian and Aristotelian conceptions of property, respectively. These two theories map onto a corresponding distinction between private (pre-institutional) rights and public (post-institutional) values. I conclude that given the legal duty of restitution and the fact that it is difficult to conceptualize a private right that could justify this type of duty on the defendant, the Aristotelian understanding is preferable