In 1998, and then again in 2000, the French government adopted laws designed to reduce working time to 35 hours a week. This article will deal with two questions concerning this legislative process, which had already been anticipated by a 1996 law on the collective reduction of working time. The first of these questions bears on the originality of the role of the State based on the co-production of legal norms, a process in which the collective bargaining plays a significant part. In this case it is how the law is designed that is under scrutiny. The second question is directed towards the implementation of the law, and involves the exploitation of part of an empirical study of negotiations and applications at a company level. Thought is given to the way in which the rules are applied and the thesis is put forward that the implementation of legal rulings blurs traditional distinctions, between, for example, individual and collective labour law, and gives rise to questions as to the ways in which company self-regulation can develop.