The cost in competititon European Law. An essay on the acceptance of a financial notion

European competition law uses economic theory and uses it increasingly. Even if it contributes to enhance the quality of competition law, the reception of competition economics into law is not unambiguous and smooth as the notion of cost illustrates : if the notion borrowed from competition economics is often central in the legal reasoning, the way this « tool » is used frequently leds to strong criticisms from doctrine and practitioners. The dissertation studies these uses, to assess whether the economic notion of cost is satisfactory used or not from a legal perspective. In order to do so, and after exposing the main features of the economic notion of cost, the role given to cost analyses in the legal reasoning as well as the determination of cost as done in European competition law are analysed.

Given the discrepancies between law and economics in the use of the notion of cost found in case-law, the study looks at the rationale explaining why law dos not necessarily follow economics when using costs. If several grounds are totally legitimate, the fact that other ones cannot be satisfactory invites to design some ways to improve the use of the notion of cost in European competition law