The core value of both international codes is that medical research cannot be performed without the freely given (uncoerced) consent of the potential subjects. In a refinement of the Nuremberg Code, the Declaration of Helsinki distinguishes between therapeutic and nontherapeutic research, requiring the physician to exercise special care in performing research that cannot personally benefit the patient. Legally, informed consent shifts the risk of nonnegligent injury to the patient in therapeutic research. In nontherapeutic research, however, it is arguable that the physician–experimenter is strictly liable (regardless of negligence) for injuries to the patient. This distinction is reflected in the federal regulations with the requirement that the risk of the experiment be compared with both the benefits to the patient and to society.