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. Background Rosa Becker and Lothar Pettkus, two immigrants to Canada, met in 1955. They moved in together and lived as husband and wife, although they did not marry, and they had no children. Until 1960, Becker paid the rent and living expenses from her outside income and Pettkus deposited his income in a bank account in his name. In 1961, they bought a farm in Quebec. The money came from Pettkus' account and ownership ("title") was taken out in his name, as was the custom in those days. They shared the farm labour and both worked very hard. They turned their farm into a profitable bee-keeping operation. Becker also earned some income which was used for household expenses and to repair the farmhouse. Their savings went back into the farm or the Pettkus bank account. In 1971, with profits from the farm and more money from Pettkus' bank account, they purchased a property in Ontario and again registered it in his name. In 1972, Becker separated from Pettkus. He threw $3,000 on the floor and told her to take it, along with a car and forty beehives with bees. At his request, she moved back in with him three months later. She returned with the car, deposited $1,900 in his account, and the forty bee-hives without the bees. Shortly thereafter, with these returned assets, joint savings and proceeds from the sale of the Quebec land, they purchased another Ontario farm in Pettkus' name. They now had two valuable pieces of land, and in 1974 they moved and built a house upon one of them. They lived off their income from their thriving bee-keeping business. In the fall of that year, she left him for good, taking the car and $2,600 in cash. She also sued for a one-half interest in the properties, bee-keeping business and assets acquired through their joint efforts. Pettkus and Becker had lived together as husband and wife for almost twenty years. Under Ontario