Little is known of the part he played at the outbreak of the Revolution. According to himself, he was part of the National Guard at its formation. He was active in the politics of his section in 1789, and in August 1792, supported the sans culotte movement. Backed by his cousin Camille Desmoulins, Fouquier de Tinville became the foreman of a jury established to pass verdict on crimes of Royalists arrested after the "journée du 10 août" in 1792.