Sébastien Grammond was appointed to the Federal Court on November 9, 2017. Prior to his appointment, he had been professor and dean of the Civil Law Section of the University of Ottawa. His research dealt with the legal recognition of Indigenous identity, Indigenous legal systems and contractual justice. He is the author or co-author of six books and numerous articles about Aboriginal law, constitutional law and contracts, including Identity Captured by Law: Membership in Canada's Indigenous Peoples and Linguistic Minorities (2009), Terms of Coexistence: Indigenous Peoples and Canadian Law) (2013 and Quebec Contract Law (2nd ed., 2016).

After studies in engineering, he obtained an LL.B. and an LL.M. from the Université de Montréal, as well as a doctorate in law from the University of Oxford. He clerked for Chief Justice Antonio Lamer of the Supreme Court of Canada. He then practiced law with Byers Casgrain (now Dentons Canada) in Montreal and continued to practice in parallel to his academic career. He was a member of the Quebec and Ontario bars. He argued several major constitutional law and civil law cases before the Supreme Court of Canada and many other cases before trial and appellate courts.

His pro bono advocacy led to a historic judgment of the Canadian Human Rights Tribunal, with respect to the discriminatory underfunding of child welfare services in First Nations communities, as well as legislative reforms regarding child welfare, customary adoption and the rights of victims of sexual assault.
He received the Quebec Bar Merit Award, the Mundell Medal for excellence in legal writing, the Ontario Bar Association President's Award and the Rights and Freedoms Award of the Quebec Human Rights Commission. He is a member of the Royal Society of Canada.