Abstract
Based on in-depth qualitative research conducted in one of the major French trade unions (the CFDT), this article explores to what extent and under what conditions trade unions adopt different legal practices to further their members' interests. In particular, it investigates how 'legal framing' has taken an increasingly pervasive place in trade union work, in increasingly decentralised industrial relations contexts, such as France. This article therefore argues that the use of the law has become a multifaceted and embedded repertoire of action for the CFDT in its attempt to consolidate its institutional power through various strategies, including collective redress and the use of legal expertise in collective bargaining and representation work.