 Guerry was born in Tours, Indre-et-Loire, the only child of Michel Guerry, a building contractor, whose family had a long history as innkeepers, merchants, farmers and trades-people.About 1817-1820 he studied at the Imperial College of Tours (now the Lyceum Descartes, founded in 1807) and subsequently studied law at the University of Poitiers.About 18241825 he moved to Paris and was admitted to the bar as a royal advocate.