Declaration of Helsinki

The Nuremberg Code of 1947 had held that voluntary informed consent was indispensable to ethical human experimentation, but it emerged from a war crimes tribunal and was never formally adopted into national law or medical practice in most countries. Physicians conducting research in the 1950s operated without a consistent professional standard. The World Medical Association, founded in 1947, spent more than a decade developing a framework grounded in medical ethics instead of criminal law and applicable to the full spectrum of research, from therapeutic trials to pure investigation.

The Declaration was adopted by the 18th World Medical Assembly in Helsinki, Finland, in June 1964. It built on the Nuremberg principles but applied them to everyday clinical research. It divided research into two kinds: clinical research combined with professional care, where the patient might also benefit, and non-therapeutic clinical research, and it set stricter conditions for the second. It required free consent after the subject had been informed, obtained in writing as a rule.

Some subjects received explicit attention. For people legally incompetent, the consent of a legal guardian was required, and investigators were told to take particular care when a subject was in a dependent relationship to them. The Declaration also acknowledged the tension between the physician's duty to the individual patient and the demands of research on that patient.

Revisions followed as research ethics evolved. The first revision, adopted in Tokyo in 1975, added review of research by an independent committee, the basis for today's research ethics committees. The 2000 revision, adopted in Edinburgh, caused considerable controversy over placebo-controlled trials and over researchers' obligations to participants after a study ended. Later revisions added requirements to register studies in a public database before recruitment and to arrange post-trial provisions for participants, and the most recent revision was adopted in Helsinki in October 2024.

The current text requires every protocol to be approved by a research ethics committee before research begins, alongside prospective protocols, explicit consent, and particular protections for vulnerable participants. By 2004, after five revisions, Carlson and colleagues described it as a guiding statement of ethical principles for doctors involved in medical research, though national regulations differ from it on specific provisions.