He has been a professor of Constitutional Law and is currently Professor of Philosophy of Law and Director of the Dipartimento di Cultura giuridica "Tarello Giovanni" at the University of Genoa. Co-founder and director of major magazines like Ragion Pratica and Analisi e diritto. He has been visiting professor at the University Pompeu Fabra (Barcelona), Cardozo School of Law (New York) and Institut des Hautes Etudes Internationales (Paris). Among his most important works fonti alle norme Dalle (1991) Distinguishing (1999), Studies in constitutional theory (2001) Studies on the legal interpretation (2004).