| Abstract: | In contrast to the moral foundations of contract, tort, and the law of property, which are generally regarded as elements of Kantian ‘right’, the liability to return the value of mistaken payments is, it is argued, an example of the law's enforcing a duty of virtue, the legalisation of the duty of beneficence in a way similar (though not identical) to how the law might instantiate a duty of easy rescue. Accordingly, one of Birks's most cherished theses – that the law of unjust enrichment represents a distinctive element of private law – can be made out: it is distinctive in having an entirely different normative source: in virtue, not in right. But this result comes at a cost: (1) a legal system could function more or less justly without such a liability; (2) Birks's thesis that liability for mistaken payment is the archetype or paradigmatic case of liability for unjust enrichment would have to be abandoned; and (3) we would have to recognise that the ground of this liability is policy‐motivated. |
