The Nuremberg Code, developed by the International Military Tribunal that tried Nazi physicians for the “experiments” they performed on unconsenting inmates of concentration camps, was the first widely recognized document to deal explicitly with the issue of informed consent and experimentation on human subjects. The first principle of the code states:

The voluntary consent of the human subject is absolutely essential. This means that the person involved should have legal capacity to give consent; should be so situated as to be able to exercise free power of choice without the intervention of any element of force, fraud, deceit, duress, over-reaching, or other ulterior form of constraint or coercion; and should have sufficient knowledge and comprehension of the elements of the subject matter involved as to enable him to make an understanding and enlightened decision. This latter element requires that before the acceptance of an affirmative decision by the experimental subject there should be made known to him the nature, duration and purpose of the experiment; the method and means by which it is to be conducted; all inconveniences and hazards reasonably to be expected; and the effects upon his health or person which may possibly come from his participation in the experiment.

All subsequent codes and regulations, insofar as they pertain to competent, adult subjects, follow these principles closely.

Although the elements of informed consent (i.e., full disclosure, adequate comprehension, voluntary choice) are easy to enumerate, recent empirical studies suggest they are not so easy to achieve. Even the best intentions do not ensure against failures of communication C information may be poorly conveyed or subjects may forget (if indeed they ever understood) that they are involved in a research project. Enhancing the likelihood that informed consent will take place is a challenge to which IRBs should respond with imagination and good judgment. When the proposed research will involve vulnerable subjects or the research design involves incomplete disclosure or deception, the challenges to the IRB are even greater. Certain populations (e.g., children or mentally retarded individuals) may not be able to understand the required information, whereas other populations (e.g., prisoners or institutionalized individuals) are so situated that the voluntariness of their consent may be in doubt. Hospitalized patients, particularly those who are seriously ill or undergoing emergency treatment, may also need special protection. Problems raised by the involvement of some vulnerable populations are discussed in other sections of this Guidebook. [See Chapter 6, “Special Classes of Subjects.”]

**Cited from the OHRP website