2026 UQ & Clayton Utz Unjust Enrichment Moot

Unjust enrichment emerged as a distinct branch of private law over the twentieth century, drawing on Roman law concepts of condictio and the equitable tradition of preventing one party from retaining a benefit at another's expense without legal justification. In the common law world, it was long obscured by the implied contract or 'quasi-contract' fiction, but the House of Lords' decision in Lipkin Gorman v Karpnale [1991] firmly recognised unjust enrichment as an independent source of obligations in English law. The Australian High Court has charted a related but distinct path, most notably in Pavey & Matthews v Paul (1987), David Securities v Commonwealth Bank (1992), and Roxborough v Rothmans (2001), preferring an approach grounded in 'unconscionability' and legal categories rather than the four-stage Birksian formula adopted in England. The core elements broadly require an enrichment of the defendant at the plaintiff's expense, in circumstances the law regards as unjust (mistake, failure of consideration, duress, illegality, ultra vires payment, etc.), absent a valid juristic basis, and subject to defences such as change of position, bona fide purchase, and ministerial receipt. Restitutionary remedies may be personal or proprietary, and the boundary with equitable doctrines such as constructive trusts, knowing receipt, and tracing remains contested. Contemporary debate centres on the divergence between English and Australian frameworks following Bofinger v Kingsway Group (2009) and Equuscorp v Haxton (2012), the role of 'absence of basis' versus 'unjust factors', the treatment of failure of consideration in subsisting contracts, the operation of change of position in commercial settings, and the proper restitutionary response to mistaken cryptocurrency and electronic transfers. These issues form the contested terrain on which the moot is fought.

Modern Anglo-Australian contract law developed from the writ of assumpsit and the nineteenth-century synthesis of offer, acceptance, consideration, and intention to create legal relations, refined through landmark decisions such as Carlill v Carbolic Smoke Ball Co (1893) and Hadley v Baxendale (1854). In Australia, the High Court has progressively localised the doctrine, departing from English authority on questions including penalties (Andrews v ANZ (2012); Paciocco (2016)), good faith, estoppel (Waltons Stores v Maher (1988)), and the implication of terms (Commonwealth Bank v Barker (2014)). Statutory overlays — the Australian Consumer Law, the Competition and Consumer Act, and equitable doctrines of unconscionable conduct — now operate alongside the common law. The relationship between contract and unjust enrichment is particularly significant for the moot. Where a contract is discharged for breach, frustrated, void, unenforceable, or rescinded, restitutionary claims may arise to recover money paid or the value of services rendered. Cases such as Baltic Shipping v Dillon (1993), Roxborough v Rothmans (2001), and Mann v Paterson Constructions (2019) interrogate when a subsisting or terminated contract bars or shapes restitution, and whether quantum meruit is capped by the contract price. Current controversies include the proper treatment of total versus partial failure of consideration, the survival of contractual allocations of risk after termination, the role of the contract as a 'juristic reason' precluding restitution, and the interaction of statutory illegality with restitutionary recovery. Delegates must navigate these contested intersections.

Equity and the law of trusts developed in the English Court of Chancery from the fifteenth century as a corrective jurisdiction tempering the rigour of the common law, eventually fused procedurally by the Judicature Acts but retaining distinct substantive doctrines. The express trust, the resulting trust, and the constructive trust form the core institutional categories, supported by fiduciary obligations, equitable tracing, and the remedies of account, rescission, and equitable compensation. In Australia, foundational authorities such as Muschinski v Dodds (1985), Baumgartner v Baumgartner (1987), Black v S Freedman & Co (1910), Farah Constructions v Say-Dee (2007), and Ancient Order of Foresters v Lifeplan (2018) define the contours of constructive trusts, knowing receipt, knowing assistance, and the disgorgement of fiduciary profits. The interaction between equity and unjust enrichment is one of the most contested areas of private law. English authority since Westdeutsche Landesbank v Islington (1996) and Foskett v McKeown (2001) has progressively rationalised resulting trusts and tracing, while the High Court of Australia in Farah and Bofinger has resisted assimilating equitable doctrines into a unified law of unjust enrichment, insisting on the continued vitality of unconscionability as the organising principle. The availability of proprietary restitutionary remedies, the threshold for imposing a remedial constructive trust, and the requisite mental element for accessory liability under Barnes v Addy remain live questions. Contemporary issues include tracing through mixed and electronic funds, the recipient liability of banks and cryptocurrency exchanges, the boundaries of fiduciary duty in commercial relationships, and whether equitable compensation should be measured on common law or trust-accounting principles following Youyang v Minter Ellison (2003) and AIB Group v Mark Redler (UK, 2014). These doctrinal fault lines provide the substantive terrain for the moot.