[1] He was educated at Collège Mont-Saint-Louis in Montreal, and in 1965 obtained his law degree from McGill University, where he was influenced by civil libertarian Frank Scott.
[1][3] He would later note that the people who inspired him in his career, in addition to Frank Scott, included Oliver Wendell Holmes and Clarence Darrow.
[4] He defended labour activist Michel Chartrand on charges of sedition in 1969, and advocated many causes for judicial reform, including changing the law to allow women to sit on a jury.
[6] During his career as a lawyer for the FLQ, Lemieux defended more than 30 terrorists and represented the members of the Chenier cell, the group behind the kidnapping of Quebec cabinet minister Pierre Laporte, who was strangled.
Lemieux argued in court that Laporte's death was accidental and suggested prime minister Pierre Trudeau was partly responsible.
[7] By 1974, Lemieux was a pariah in Montreal legal circles, and subsequently decided to move to Quebec's North Shore,[1] where he pumped gasoline at a service station for a while until he was able to resume his law practice.