Discipline and Punish
As a co-founder of the Groupe d'Information sur les Prisons (GIP)—a group that was active in France for several years in the early 1970s—Foucault was highly critical of the French penal system, believing that it converted petty criminals into hardened delinquents. A year after the GIP folded, Foucault published "Discipline and Punish", in which he examined the evolution of penal system, away from corporal and capital punishment, into the modern carceral system that began in Europe and the United States around the end of the 18th century. His biographer Didier Eribon described "Discipline and Punish" as "perhaps the finest" of Foucault's works.