Résumé : This article deals with the relation- ship between law and power in the production of EU legitimacy. It argues that in order to account for specific challenges to EU legitimacy such as populism, a historical sociology approach is needed. After discussing this approach in the first part, this article highlights how law can play a role in processes of decivilization. In the last part, I apply this approach to the use of constitu- tional arguments in the debates around the Maastricht Treaty in France and Germany.