Since the 90's, the alleged threat of transnational organised crime has led to numerous discourses on the urgency of cooperation at the international level, contributing to the establishment of many international experts groups. This intensification of working groups has created professional networks of expertise in the field of the fight against transnational organised crime, and more recently, terrorism, and has generated numerous recommendations and so-called best practices. This paper is an attempt to highlight the dynamics of this expertise, looking at the modalities of this transnational exchange and the circulation of norms at the global level.