(B) IDENTIFICATION OF THE CAUSE OF ACTION IN UNJUST ENRICHMENT CLAIMS

Rather than the pleadings formulating a claim for restitution with reference to the old forms of action, it would be preferable to formulate the claim with explicit reference to the unjust enrichment principle. Unjust enrichment cannot, however, be pleaded as a cause of action in its own right,^[1] since it is too vague to be acceptable.^[2] Rather, the unjust enrichment principle consists of a number of different causes of action, distinguished by reference to particular grounds of restitution, such as the cause of action for total failure of basis and that for the recovery of money paid under a mistake.^[3] It follows that the pleading of a claim in unjust enrichment operates in a similar way to the pleading of a claim in tort. Tort as such is not a cause of action, but a category of related causes of action connected by wrongdoing. It would never be acceptable for the claimant simply to sue the defendant in tort; the particular tort and its constituent elements need to be identified. The same is true of unjust enrichment; the particular claim within unjust enrichment and its constituent elements need to be identified.

This analysis of the cause of action in unjust enrichment is consistent with the other two principles which trigger restitutionary remedies. So, where the restitutionary claim is founded on the defendant’s wrongdoing, it is not sufficient merely to say that the claim is founded on a wrong; it is necessary to identify the particular type of wrongdoing which is alleged. Similarly, where the claim is founded on the vindication of property rights, it is necessary to identify the right which the claimant seeks to vindicate and sometimes to formulate the claim with some precision, as is the case where, for example, the claim is founded on the action for unconscionable receipt.^[4]

• [1] Uren v First National Home Finance Ltd [2005] EWHC 2529 (Ch), [16] (Mann J).
• [2] As was recognized by Dawson J in David Securities Pty Ltd v Commonwealth Bank of Australia (1992)175 CLR 353, 406.
• [3] F J Chalke Ltd v The Commissioners for Her Majesty’s Revenue and Customs [2009] EWHC 952 (Ch),
• [4] [2009] STC 2007, [127] (Henderson J); Test Claimants in the FII Group Litigation v Commissioners for HMRevenue and Customs [2014] EWHC 4302 (Ch), [248]. See also Deutsche Morgan Grenfell Group plc v IRC[2006] UKHL 49, [2007] 1 AC 558, [17] (Lord Hoffmann). 96 See Chapter 22.