 He was born in Saint-Laurent on the Île d'Orléans in 1824, the son of Jean Langlois and Marie Labrecque, and studied at the Séminaire de Québec.He was called to the bar in 1847 and became a Queen's Counsel in 1867.Langlois was partner in a law firm in Quebec City with Louis-Napoléon Casault.