How far do criminal understand the criminal law? Evidence from French mandatory sentencing

This paper documents how quickly and how precisely would-be offenders understand and adapt to criminal law. It relies on a mandatory sentencing act against repeat offenders passed by the French parliament in August 2007. It exploits the gap between the public presentation of the law – an overall increase in the severity of sentences on repeat offenders – and the enforcement – an increase on a specific subgroup of repeat offenders. Using duration model and competitive risk analysis on individual data representing the universe of convictions that occurred in France during this period, this paper studies the evolution of the two instantaneous probabilities of committing a new crime targeted or not targeted by the law. The analysis shows that the law equally deterred targeted and untargeted crimes in the short term while only targeted behaviors remain affected in the medium term. These results provide evidence that even a strongly distorted presentation failed to mislead people for a long time. They are coherent with a learning effect of complex criminal law. This learning effect goes faster for more rational criminals or older offenders.