The article is based on the controversies relating to conducting experiments and licensing AIDS treatments in France in the 1980s and 1990s. We have identified two political operators, i.e. two issues around which tensions have grown between the different generations of actors involved in these controversies: 1) the way of thinking about patient autonomy, and 2) the way in which objectivity regarding medical decisions is built. The article shows that there are several regimes of objectivity and autonomy, and that it is at the meeting point of the two dimensions that very different political forms of medicine have developed. In the case of AIDS, the article identifies four of these forms (liberal and conservative clinical traditions and therapeutic modernity--enclosed, then participative) and analyzes the dynamics of their emergence and opposition. We discuss an "objectivity/autonomy" diagram as a conceptual framework which enables us (above and beyond AIDS) to think about changes in contemporary medicine.