In 2002, Belgium and France implemented a law that places patients and their right to autonomy at the center of the healthcare system. Based on the assumption that concepts and principles cannot be perceived independently of the way they are likely to be implemented in “ordinary life”, I applied an empirical-philosophical approach to the research field by choosing to examine what can be described as a borderline situation, bringing my attention to the issue of consent to medical care of patients with Alzheimer’s disease hospitalized in geriatric units for an acute health issue. Indeed, Alzheimer’s disease involves a decline of the patient’s abilities (including cognitive skills), thereby jeopardizing his autonomy. The specific characteristics of the disease coupled with the acute medical care it requires single it out as the perfect ground to question the meaning and limitations of the principle and its current use in the healthcare system.The reflection proposed in this thesis is based on information gathered during a comparative field study (including various Belgian and French hospital sites) specifically set up for the purpose of this work. The research focused on the relationship between the patients and the “immediate caregivers” (nursing staff), where the capacity of autonomy of Alzheimer patients in a hospital setting is most frequently questioned. Moreover, the present study largely dealt with the issue of treatment refusal by patients as well as the use of coercion. It is indeed mainly in this type of situation that the problem of respecting patient’s autonomy and obtaining their consent is most vividly debated in the present field of study.The introduction of this research field must be seen as a methodological and epistemological tool that aims at providing further conceptual, critical and normative inputs to the issue of respect of autonomy for patients suffering from Alzheimer’s disease.This work allowed me to develop a new understanding of autonomy, which differs from the most frequently proposed ...