What is the current state of the law on unjust retention of benefits?

If it was not well-settled when the trial judge rendered his decision in July 2009, it is now firmly established that a claim alleging unjust retention of a benefit conferred in an ineffective transaction is a discrete category of the doctrine of unjust enrichment, which may attract a personal monetary remedy (Kerr v. Beranow, 2011 SCC 10 at para. 31) and that remedy must match, as best it can, the extent of the enrichment unjustly retained by the defendant (at para. 73).

In order to access the remedy, the plaintiff must show the defendant’s unjust enrichment. Unjust enrichment has three requirements: Kerr v. Baranow, 2011 SCC 10 at para. 32 [Kerr]: (1) An enrichment of the defendant; (2) A corresponding deprivation of the plaintiff; and (3) An absence of the juristic reason for the enrichment.