- 17 A classically difficult situation arises when the patient's decision conflicts with the general duty of care incumbent on the doctor. This might happen when the patient is influenced by personal beliefs (eg. refusal of a blood transfusion) or when he is intent on using his body, or even mutilating himself, in order to press his demands, protest against an authority or demonstrate his support for a cause. In the event of a hunger strike, public authorities or professional organisations in some countries will require the doctor to intervene to prevent death as soon as the patient's consciousness becomes seriously impaired. In other countries, the rule is to leave clinical decisions to the doctor in charge, after he has sought advice and weighed up all the relevant facts. 48. As regards the issue of medical research with prisoners, it is clear that a very cautious approach must be followed, given the risk of prisoners' agreement to participate being influenced by their penal situation. Safeguards should exist to ensure that any prisoner concerned has given his free and informed consent. The rules applied should be those prevailing in the community, with the intervention of a board of ethics. The CPT would add that it favours research concerning custodial pathology or epidemiology or other aspects specific to the condition of prisoners. 49. The involvement of prisoners in the teaching programmes of students should require the prisoners' consent. ii) confidentiality 50. Medical secrecy should be observed in prisons in the same way as in the community. Keeping patients' files should be the doctor's responsibility. 51. All medical examinations of prisoners (whether on arrival or at a later stage) should be conducted out of the hearing and - unless the doctor concerned requests otherwise - out of the sight of prison officers. Further, prisoners should be examined on an individual basis, not in groups. d. Preventive health care 52. The task of prison health care services should not be limited to treating sick patients. They should also be entrusted with responsibility for social and preventive medicine.