Australasian Conference Association Ltd v Mainline Constructions Pty Ltd (in Liq)

The High Court of Australia considered an appeal from the Supreme Court of New South Wales concerning a dispute between Australasian Conference Association Ltd (ACA) and Mainline Constructions Pty Ltd (in Liq). The core of the disagreement lay in whether ACA was liable to pay Mainline Constructions for work performed on a property at Cooranbong, New South Wales, despite the absence of a formal, executed contract. Mainline Constructions had undertaken substantial construction work on land owned by ACA, but the formal contract was never signed by both parties.

The central legal question before the High Court was whether ACA had, by its conduct, accepted the benefit of the work performed by Mainline Constructions in circumstances that gave rise to an obligation to pay for that work, even without a formal contract. This involved determining whether the principles of unjust enrichment or a quasi-contractual obligation could be established, or alternatively, whether ACA was estopped from denying the existence of a contract. The court also had to consider the effect of ACA's knowledge of the work being carried out and its purported acceptance of the benefits derived from that work.

The High Court, in a majority decision, found that ACA was liable to pay Mainline Constructions. The court reasoned that ACA had, through its conduct, unequivocally accepted the benefits of the work performed by Mainline Constructions. This acceptance, coupled with ACA's knowledge that the work was being done in expectation of payment, created an obligation to pay. The court applied the principles of quasi-contract, holding that it would be unjust for ACA to retain the benefit of the work without making reasonable payment. The court distinguished this situation from one where a party merely acquiesces to work being done, emphasizing that ACA's actions went beyond mere acquiescence to active acceptance of the completed construction.

Consequently, the High Court dismissed the appeal and affirmed the decision of the Supreme Court of New South Wales, ordering ACA to pay Mainline Constructions the sum awarded by the lower court for the work performed.