Liu v A and a Martins Pty Limited

The appeal concerned a claim for restitution based on unjust enrichment brought by the respondent against the appellants in the ACT Supreme Court. The central dispute revolved around whether the respondent was entitled to recover money paid to the appellants, alleging that the work performed was not done at the appellants' request. The appellants sought to raise defences including *Anshun* estoppel and argued that the respondent's claim constituted an abuse of process.

The court was required to determine whether the respondent had established a claim for restitution on the grounds of unjust enrichment. This involved assessing whether the appellants had been enriched at the respondent's expense, whether that enrichment was unjust, and whether there was an absence of a good reason for the appellants to retain the enrichment. Furthermore, the court had to consider the applicability of *Anshun* estoppel and whether the respondent's claim amounted to an abuse of process, particularly in light of previous proceedings between the parties.

The court reasoned that for a claim in unjust enrichment to succeed, the respondent bore the onus of proving the three elements: enrichment, at the expense of the respondent, and that the enrichment was unjust. The court found that the respondent had failed to establish that the work was not done at the appellants' request, which was a crucial element for the claim of unjust enrichment. Consequently, the court determined that the respondent had not discharged its burden of proof. Regarding the abuse of process argument, the court found that the respondent's claim was not an abuse of process, but the failure to establish the elements of unjust enrichment meant the claim could not succeed on that basis.

The appeal was allowed, and the orders of the ACT Supreme Court were set aside. The court ordered that the respondent's claim be dismissed.