Patient information is now an ethical and legal obligation in France; it is the physician who is required to provide proof. The Law of March 4, 2002 and the code of ethics and main legal and regulatory texts are, however, imprecise on some points. Written documents, although not stipulated in law, are in practice essential, supplementing the indispensable oral information given by the surgeon in individual personalized interview. Patients remember only some of this information, and overestimate their own understanding of it. Written documents are therefore essential to compensate for this. Their contents need validation by scientific societies. In case of disagreement, the medical file is the essential means of assessing information quality, and should be kept up to date as rigorously as possible. A key document is the letter summarizing the preoperative consultation, validating surgery, which should be drawn up in a manner that meets the obligation to inform. Signed consent is not mandatory in law, but is necessary in practice and should be archived. For judges, proof of information is based on several elements: the complete structured letter to the patient and community physician plus the signed information sheet and consent form constitute solid evidence and all three should be included in the medical file. Information has now become a part of health-care in itself. In a context of increasing litigation, “defensive medicine” is still to be avoided but physicians should have their own check-lists so as to be in a position to prove delivery of structured information if called upon to do so. In the absence of proven information, patients can plead loss of chance and/or prejudice for lack of preparation and/or infringement of dignity, and claim damages from the courts.