Pettkus v Becker [1980] 2 S.C.R. 834 was a landmark family law decision of the Supreme Court of Canada. The Court established a new formulation of the constructive trust as a remedy for unjust enrichment based on the ideas of Professor Donovan Waters, and in particular the requirements for such constructive trust in a common law relationship separation. The Pettkus formulation of constructive trust was subsequently adopted elsewhere in the common law world.