[Criminal madness in the 18th century].

Forensic psychiatry, as we know it, was established in the early 19th century. But already the "Ancien Régime" knew--with regard to mentally disturbed criminals--particular legal and medical considerations and practical arrangements. The author analyses the theoretical reasoning of some cases selected from the judicial archives of Geneva (mainly 18th c.). This enables him to establish the great lines of a "prehistory" of forensic-psychiatric expertise.