Résumé
The diversity of expertise' situations in the European Commission's Directorate-General for Agriculture and Rural Development invites to keep off a normative conception of experts and expertise. From a deep fieldwork in two agricultural sectors, tobacco and beet, the article analyzes the functioning of two specific groups: experts committees and advisory groups, in the DG Agri. These groups are composed indistinctly of "experts", but their profile and their missions are completely different. In comparing the running of advisory groups, the article shows how these kinds of groups function as real socialization units. Experts internalize cognitive systems and suitable behaviors, which correspond to the way that public action must be at the European level. For "sugar experts", the technicity range is completely internalized whereas the tobacco experts are stigmatized, and refuse to adopt "the good" norms and behaviors. The technicity and the scientificity of debates made it a rule and disqualify the others types of speeches. In other words, the European commission develops his capacities of production and of prescription of norms and standards of public action, by the functioning of experts groups.