Economics of a flexible law.

Summary A flexible law is a law that leaves a margin of discretion to the judge. It is characterized by general or "incomplete" rules. This margin of discretion has a cost: the reduction of the information given by the law to agents. In a context where the complexity of the law is increasing exponentially, the question of the rationality of a flexible law arises. In other words, should legal rules be incomplete or should they specify all contingencies? This thesis fits into the literature of economic analysis of rule characteristics by analyzing the problem from the perspective of law production. First, a theoretical treatment of rule formulation using real options theory is presented in order to contribute to the understanding of the existence of incomplete rules in complex and innovative environments. The question of the basis for public authority intervention is then raised. The choice between a flexible regime, based on the occurrence of harm, and a rigid regime, based on the detection of the activity, depends on the information of the legislator and the agents on the risk. The influence of the degree of precision of the rules on the amicable resolution of disputes is analyzed. This study allows us to justify in part the production of soft law by private parties. Finally, the notion of flexibility is applied to the controversy about the effectiveness of legal harmonization as a solution to jurisdictional competition. The problem of asylum law is considered. Incompleteness of legal rules is thus justified when circumstances vary greatly and when the field is innovative. Otherwise, the precision of the rules informs the agents: it is thus necessary in a context of under or over estimation of the agents' risk and as an aid to the resolution of disputes.