(C) IS THERE A CONTINUING ROLE FOR THE ESTOPPEL DEFENCE?

In the light of the recognition of the defence of change of position, a defence which operates only to the extent that the defendant’s circumstances have in fact changed, there is a very strong argument for saying that there is no longer any role for estoppel as a defence to restitutionary claims. Indeed, in RBC Dominion Securities Inc v Dawson⁵⁶ the Newfoundland Court of Appeal held that the recognition of the defence of change of position meant that the defence of estoppel was no longer available in respect of restitutionary claims.

It is not possible, however, to conclude in England that the recognition of the change of position defence means that there is no longer a role for the defence of estoppel to restitutionary claims. Indeed, in recognizing the defence of change of position in Lipkin Gorman (a firm) v Karpnale Ltd⁵⁷ Lord Goff assumed that there was a continuing role for the defence of estoppel.^[1] The two defences do operate in a different way, in that estoppel requires proof of a representation, whether collateral or implied, and arguably change of position requires a more extraordinary change of circumstances than is the case for estoppel. Also estoppel requires proof of reliance on the representation, whereas change of position typically requires proof of reliance on receipt of a benefit. But the crucial difference between the two defences is that estoppel can typically defeat the claim completely whereas change of position only defeats the claim to the extent that the defendant’s position has changed. It follows that estoppel will continue to be the defence which the defendant will prefer to plead as long as he or she can establish the necessary representation.^[2] But with the growing recognition that the estoppel defence should not bar the restitutionary claim completely, it is likely that the defence will cease to have any function in the law of restitution.^[3]

• [1] Bant, The Change of Position Defence, 230, considers it to be premature to assume that estoppel has beensubsumed within the change of position defence or has been rendered redundant.
• [2] The Law Commission favoured the retention of the estoppel defence despite the recognition of the
• [3] defence of change of position: Restitution: Mistakes of Law and Ultra Vires Public Authority Receipts andPayments (Law Com No 227, 1994), 48-9 and 141. See also Hudson, ‘Estoppel by Representation as a Defenceto Unjust Enrichment—the Vine Has Not Withered Yet’, who defends the continued operation of estoppel as acomplete defence as being true to its original function as an evidential rule which prevents the claimant fromadducing evidence contrary to the represented facts. 60 See p 698, below.