After the war, Morgentaler migrated to Canada and entered medical practice, becoming one of the first Canadian doctors to perform vasectomies, to insert intrauterine devices, and to provide birth control pills to unmarried women. He opened his first abortion clinic in 1969 in Montreal, challenging what he saw as an unjust law placing burdensome restrictions on women seeking abortions. He was the first doctor in North America to use vacuum aspiration and went on to open twenty clinics and train more than one hundred doctors. Morgentaler twice challenged the constitutionality of the federal abortion law, losing the first time, in "Morgentaler v R" in 1975, but winning the second time, in "R v Morgentaler" in 1988.