Recovering money paid under a mistake of fact

Last week's Supreme Court of Canada decision in B.M.P. Global Distribution. Inc. v. Bank of Nova Scotia, 2009 SCC 15 provides a good restatement of the law relating to recovery of money paid under a mistake of fact. The Court writes (para 22):

1. If a person pays money to another under a mistake of fact which causes him to make the payment, he is prima facie entitled to recover it as money paid under a mistake of fact.
2. His claim may however fail if: (a) the payor intends that the payee shall have the money at all events, whether the fact be true or false, or is deemed in law so to intend; (b) the payment is made for good consideration, in particular if the money is paid to discharge, and does discharge, a debt owed to the payee (or a principal on whose behalf he is authorised to receive the payment) by the payer or by a third party by whom he is authorised to discharge the debt; (c) the payee has changed his position in good faith, or is deemed in law to have done