This article argues that while France's old penology remains well defended due to professional discretion and individualization of professional judgment in high security prisons (maisons centrales), a new penal trend akin to an actuarial justice is observed in detention centres. This trend consists in governing 'at a distance' a mixed population of very different prisoner types. However, a cacophony of voices in the decision-making process, discretion, professional and unions stakes, face-to-face interactions, abilities of inmates to negotiate with staff members as well as disconnections and contradictions between fields of decision making are factors that explain the failure of the new penology in the most secure prisons. These organizational and professional factors are not linked to political conditions such as the welfare state or the new management of poverty as indicated by the authors of the new penology.