Yann has served as the Secretary General of the Commission Nationale de l'Informatique et des Libertés (CNIL) since 2006. He started his public career as an Administrator of the French National Assembly, and was then appointed to the Commission des Lois, where for seven years he was in charge of the section dealing with information technology, criminal law, and criminal proceedings. In this role, Yann was involved with the implementation in France of the European Commission's Directive 95/46/EC on data protection. He addressed topics such as the presumption of innocence, national security, the development of the law in response to evolving criminal sophistication, the trade in humans, and recidivism. Yann has published numerous articles on the relationships between criminal law and information technology, such as the use of DNA in criminal proceedings, on cybercrime, and on the rights of the individual when dealing with electronic files.