Pre-print, Working paper: This paper studies the implementation of bankruptcy law in 19th century France. It uses two sources: first, the annual exhaustive statistical appraisal of bankruptcies published from 1840 on; second, individual bankruptcy files conserved at the Paris Merchant Court archives. We show that the changes in bankruptcy law cannot explain the changes in the number and size of bankruptcies, suggesting changes in the practice of the courts as well as in the behaviour of firms. Most importantly, the Parisian example suggests that the courts didn't treat all firms on the same basis, privileging the important ones. This gives new arguments against a purely legalistic and retrospective vision of the impact of bankruptcy law on economic activity, and in favour of an empirical study of its concrete implementation.