The education bill for 1989, remembered for its catchphrase, “Mettre l’élève au centre du système” – “Place the pupil at the heart of the system”, and for its establishment of Instituts Universitaires de Formation des Maîtres or Teacher-training university centres, is usually thought to be the result of pedagogical expertise. Yet the way the law was drafted shows no such recourse to pedagogical expertise. If expertise there was, it needs to be analysed in the impoverished shape it took as echoes or traces appropriated according to the interests and representations of the social actors involved in order to better serve a priori political interests – to wit, a series of beliefs in the modernisation and reform of the State. A precise study of the way the text was elaborated leads us to rethink the use of expertise and of the diffusion of knowledge in the elaboration of public policy.