The problem of contraception, sterilisation and the mentally ill is one of the key questions in medical ethics. Even if these two aspects bring into question a person's autonomy in two of the most intimate and fundamental aspects of life — sexuality and motherhood — they should not be confused as they differ greatly in terms of their reversibility. The essential question is rather one of individual freedom and its defence in situations where the subject is unable to defend himself either temporarily or in the long term. The fine line between individual and collective interests poses questions in terms of where to draw this line and the way in which it is defined in care situations. From this viewpoint, carers — that is, doctors and nurses, but also social workers and the patient's entourage — play an important role, not only in theory but also in day-to-day reality.