Article L722-3 of the French Code governing the entry and residence of foreign nationals and the right of asylum
The administrative authority may initiate the procedure for automatic enforcement of the decision imposing an obligation to leave French territory as soon as the period for voluntary departure has expired or, if no period has been granted, as soon as the obligation to leave French territory has been notified or, if the period granted has been terminated, as soon as the decision to terminate the period has been notified.