Mr. Justice Mainville was born in Montreal. He studied law at the Université de Montréal (LL.L.) and at McGill University (LL.M.). He was admitted to the Quebec Bar in 1976.
In the course of a long career as a barrister and solicitor, Mr. Justice Mainville distinguished himself principally in the fields of aboriginal law and labour law. He was a pioneer in the development of aboriginal law in Canada. He notably acted as the principal negotiator of the 2002 Paix des braves agreement between the Quebec government and the Crees of Quebec, and with respect to numerous other agreements involving aboriginal peoples. He also acted as the management spokesperson for the negotiation of numerous Quebec public service collective labour agreements. He also practiced law in the fields of constitutional and administrative law and in civil law, while actively involved in transnational commercial activities involving patents of invention.
Mr. Justice Mainville has appeared as lead counsel before all the courts of Quebec and all the federal courts, including numerous times before the Supreme Court of Canada.
Before his appointment as a judge, he was a partner in Montreal with the law firm Gowling Lafleur Henderson, where he led the national practice group in aboriginal law.
Mr. Justice Mainville also lectured for a few years at McGill University’s faculty of law. He has participated in numerous conferences and written various articles concerning aboriginal law issues. He has also authored two books concerning aboriginal law matters.
He was appointed to the Federal Court in June of 2009, and was also appointed shortly thereafter as a judicial member of the Competition Tribunal of Canada. He was appointed to the Federal Court of Appeal in June of 2010 and to the Quebec Court of Appeal in July 2014. In addition to his functions with the Quebec Court of Appeal, Mr. Justice Mainville is also a designated judge of the Court Martial Appeal Court of Canada.