This period of reporting1 has passed without any further contributions to restitutionary jurisprudence from the High Court of Australia. There are a dozen or so appellate decisions of significance, most of which emanate from the New South Wales Court of Appeal. The cases continue to consolidate and apply the High Court’s conservative conception of unjust enrichment, not as a single, definitive cause of action, but as providing a principled framework for analysing a variety of different restitutionary claims that must be pleaded and proven in accordance with more precise criteria (Trimat §31 at [115]). For restitutionary relief to be granted, courts are hence accepting that a defendant “must have received a benefit, at the plaintiff’s expense, in circumstances where there is a recognised vitiating factor or unjust element that calls for restitution (and no countervailing factor against the grant of such relief)” (Earth Civil §19 at [2752], per Ward CJ in Eq); but there is no sense that this four-stage approach provides a “test” of liability, or the “elements” of a single unjust enrichment claim, akin to the “elements” one might plead to make out a particular tort, for example. The continued reference to the four-stage approach is significant. Prior to Mann v Paterson Constructions Pty Ltd [2019] HCA 32; 267 CLR 560, there had been some suggestion that that approach might be inconsistent with the High Court’s understanding of unjust enrichment’s limited role (see, eg, the Victorian Court of Appeal in Southage Pty Ltd (ACN 050 240 965) v Vescovi [2015] VSCA 117, [48–49]). However, that proposition has since been rejected. While the High Court has long ruled out unjust enrichment as constituting a cause of action in its own right, Nettle, Gordan and Edelman JJ in Mann clearly recognised the utility of the staged analysis as a device for guiding judges through the right analytical questions, indicating at [213] that they may:

This stance is very similar to Lord Reed’s suggestion in Investment Trust Companies v HMRC [2017] UKSC 29; [2018] AC 275 at 295 [41–42], that the four-stage approach provides a set of “signposts” to the key issues, not definitive criteria that can be pleaded in the abstract without more detailed, concrete elaboration. In the same way that claims for “unjust loss” in our civil law are varied, but share certain basic, conceptual elements (loss/harm, injustice in a defined legal sense, a causal relationship between the two), the various