Pietro Costa has taught History of Law at the Universities of Salerno and Macerata, and History of Medieval Law at the Università di Firenze. He was director of the prestigious magazine Quaderni Fiorentini per la storia del pensiero giuridico moderno, founded by Paolo Grossi, and is a member of the board of advisors of Diritto pubblico. His research interests include the history of citizenship, the history of justice, democracy and colonial law.