International audience Following several crises, the French Food Safety Agency was set up in 1999 to solicit scientific opinions as part of assessments of health-related risks. The principle was retained to avoid a conflict of professional and economic interests in making assessments. Observations of how a committee of experts on prions operated has shown that its judgement is the outcome of a variety of resources and procedures (involvement in quite contextualized technical studies, a sharing of tasks with the agency's personnel, etc.). The actual work of the experts involved taking into account both the requirement of legitimation and a concern for examining the case presented and answering the questions that were set.