This paper uses the universe of convictions occurred in France between 2000 and 2003 to document the gender gap in criminal justice. First, during this period, and after controlling for very precise description of the offenses as well as other observable characteristics, women get prison sentences 15 days shorter than men on average. This represents a 33% decrease in comparison to the average prison length in the sample (44 days). Second, this gender gap is also observed within pairs of criminals, each consisting of one man and one woman, who are convicted together, on the same day, by the same person and for the same crime. Lastly, this paper present robust evidences that the gender gap is affected by the judges' gender but not the prosecutors' gender. Using the evolution of courts' composition between 2000 and 2003, results show that a one-standard-deviation increase in the number of women in the court decreases the gender gap by 10%.