This article analyses the process of drafting the Bachelot Bill on technological risks passed on July 30, 2003 but initiated by Lionel Jospin's cabinet immediately following the AZF chemical plant disaster in September 2001. It focuses on the practical work of the civil servants at the Ministry of Ecology responsible for deciding on the orientations of the reform, for transcribing them into legal language and ensuring the provisions are supported and passed in Parliament. The analysis hunts down both the successive versions of the bill and the multiple documents used in the preparatory phase. Delving into the administrative production of the law provides a better understanding of the relations between the civil service and the political authorities, and shows how difficult it is to draw the boundary between those two worlds of practice.