In 1947, following the trials of Nazi war criminals engaged in human experimentation, a set of principles for human subjects research were adopted. The Nuremburg Code established the following principles:
- Voluntary informed consent is essential
- Research should yield useful results
- Research should be based on previous work
- Physical and mental suffering must be avoided
- There should be no expectations of death or disabling injury
- Risk must be outweighed by importance of research
- Subjects must be protected from injury
- scientists must be qualified and facilities adequate
- subject must be free to withdraw at any time