The idea that offenders respond to the costs and benefits of crime dates to the eighteenth century, following Beccaria and Bentham. Becker [1968] provided the first modern and mathematical treatment of the subject, giving a new impetus to the school of thoughts initiated in the 18th century. The main levers of criminal law are the probability of being caught and the severity of the sanction. It is widely accepted that the probability has an influence on crime level (Garoupa [1999]; Polinsky and Shavell [2000]). In this context, an increase in police forces has a negative influence on crime level (Marvell and Moody [1996]; Levitt [1997]). The impact of the severity of the sanction appears to be more undermined.
