The administrative judge has the task of determining the extent of prison responsibility in cases of injury to prisoners. Establishing culpability of the institution requires proof of grave error by agents of the penitentiary. The prison is expected to protect inmates from extremely aggressive prisoners and from themselves. In fact, the prison must consider the reactions of each individual from the time he enters the institution because insufficient evaluation of risks and inadequate precautions can be considered a grave error, as can failure to recognize early disquieting signs and take preventive precautions against inmates who cause injuries. The institution does not bear responsibility for job-related accidents because there is no actual contractual work relationship between inmates and institution. However, the institution may be held responsible in certain cases, e.g., when supervision is inadequate or when a contractual agreement between the prison and the work contractor entails obligations which have been violated. Abandonment of the concept of grave error for one of simple error is impractical, as absolute obligation of the penitentiary for inmates' safety from any risk is not feasible in a prison setting where so many of the individuals involved are dangerous. An appendix contains case descriptions and decisions of the Council of State on prison responsibility. --in French.