(D) CONSEQUENTIAL BENEFITS

Analysing the ‘at the claimant’s expense’ requirement as embodying a test of causation provides a ready solution to the difficult problem of whether a defendant who has been

See p 177, below.

unjustly enriched is also liable for benefits resulting from the receipt of the original benefit from the claimant. If, for example, the claimant pays the defendant ?100 by mistake and the defendant spends that money on National Lottery tickets, one of which wins the ?10 million jackpot, is the claimant confined to a claim to recover ?100, or is it possible to recover the ?10 million as being a gain made at the claimant’s expense?^[1] If the claimant can establish a proprietary claim to the money paid by mistake, it might be possible to claim the jackpot.^[2] But, as regards a claim in unjust enrichment, the defendant’s decision to purchase the National Lottery tickets should be considered to be a voluntary decision which breaks the chain of causation, such that the jackpot cannot be considered to be obtained at the expense of the claimant. In other words, purchasing the tickets is a distinct transaction which breaks the chain of causation, even if it can be shown that, had the defendant not received the money paid by mistake, she would not have purchased the tickets. This is another reason why reliance on a ‘but for’ test of causation is not by itself sufficient to explain when a benefit is properly treated as being obtained at the expense of the claimant.^[3]

[1] If the correspondence principle is recognized, whereby the defendant’s gain is capped by the claimant’sloss, the claimant will anyway be limited to claiming the money paid. See below.
[2] See Chapter 21. 3 See further p 107, above.
[3] 58 See Chase Manhattan NA v Israel British Bank (London) Ltd [1981] Ch 105,125 (Goulding J) and Banque