Andrew Burrows takes the view that ‘enrichment owed’ is a denial rather than a defence, in other words, an ‘upfront’ matter relating to prima facie liability, specifically to the element of ‘unjust’: ‘the prima facie injustice established by the unjust factor is normally outweighed by the fact that the defendant is legally entitled to the enrichment’. However, it is argued here that an unjust factor such as mistake and the defendant’s entitlement to the benefit are after all not commensurable considerations capable of overriding or outweighing one another; entitlement is a defence, not a denial. For the same reason, it is impossible to mix the unjust factor and absence of basis approaches at the same level. But even if Burrows is correct, there remain crucial differences between denials and causes of action. Even if the legal burden of proving the invalidity of an apparent legal obligation were placed on the claimant, in English law it would generally be for the defendant to put the existence of such an obligation in issue. In South African law, on the other hand, the plaintiff cannot make out even a prima facie case without pleading the absence of any liability on his part to make the transfer: such non-liability (in combination with his mistake) constitutes the gist of the plaintiff’s claim.
Scott, Helen, Defence, Denial or Cause of Action? ‘Enrichment Owed’ and the Absence of a Legal Ground (October 6, 2015). Available as ch 3 in A Dyson, J Goudkamp, and F Wilmot-Smith, eds, Defences in Unjust Enrichment (Oxford, Hart, 2016) 53-68.