This research project seeks to produce new knowledge in criminal law in France through an approach of Law & Economics and Economics of Crime. Using administrative data, our goal is to analyze the way judges and prosecutors integrate (or not) in their decisions the constraints and specificities of the French prison system, notably the overcrowding that affects most jails. Another objective is to study how prison conditions impact individual risks of reoffending among prisoners, exploiting a variety of information from each prison. More generally, this project is embedded into the "Observatoire des disparités dans la justice pénale" (www.observatoire-disparites-justice-penale.fr), which analyzes and distributes numerous data on these issues.