French lawyer.

Director of the Académie de La Rochelle (c. 1766). Correspondent of Voltaire. Avocat général au parelement de Bordeaux. Opposed royal power; twice arrested and imprisoned (1770, 1771-74). Commissioned to study penal reform in Italy (1784). Author of Lettres sur l’Italie en 1785 (2 vols., 1788) and Lettres sur la procédure criminelle de la France (1788).

Son of Charles-Jean-Baptiste Mercier and Louise-Élisabeth (Carré) Dupaty. Educated the collège de Beauvais. Married Louise Fréteau de Pény de Saint-Just (1769); seven children.