This article is concerned with the question whether a defendant in an unjust enrichment action can reduce or eliminate its liability by establishing that it could have obtained the enrichment (or part of it) from the claimant in a way that would not have given rise to liability. The answer in principle ought to be no. In arguing for that conclusion, I consider the meaning of “enrichment” and “loss”, the nature of the change of position defence and the basis of liability for unjust enrichment in cases involving ultra vires charges by public authorities and the taking of money without consent by private defendants.