The scepticism that the High Court of Australia has directed towards unjust enrichment has been widely documented.1 Having abandoned the quasi-contract explanation for restitution in favour of acknowledging unjust enrichment as a “unifying legal concept”,2 the High Court has subsequently insisted that unjust enrichment be “seen as a concept rather than a definitive legal principle”.3 The primary explanation provided for this conceptual approach to unjust enrichment has been to preclude its mechanical application premised on “top-down reasoning” which may distort well-settled doctrines and undermine the traditional development of the law where principles are derived from judicial decisions.4 This approach has been reiterated on numerous occasions,5 and the three-pronged rationalisation of unjust enrichment claims—that is, the process of identifying a benefit, obtained at the claimant’s expense, which it would be unconscionable for the defendant to retain—has been commended for removing the legal fictions and opaque reasoning associated with the traditional forms of action for restitutionary claims.6 However, the unifying focus unjust enrichment provides with respect to restitutionary principles in Australian law remains fragile. For example, in the recent case Lumbers v W Cook Builders Pty Ltd (in liquidation),7 Gummow, Hayne, Crennan and Kiefel JJ appeared to express a preference for the traditional forms of action when suggesting that “a framework for analysis expressed only at the level of abstraction … by reference to ‘benefit’, ‘expense’ and ‘acceptance’ coupled with considerations of unconscionability, creates a serious risk of producing a result that is discordant with accepted principle, thus creating a lack of coherence with other branches of the law”.8