While stating that nothing should be said to inhibit the development of the defence, Lord Goff in Lipkin Gorman Karpnale made it clear at 580 that:

the defence is not open to one who has changed his position in bad faith … the defence should not be open to a wrongdoer.

He gave as an example of bad faith a defendant who had paid away the money, with knowledge of the facts entitling the claimant to restitution.