The Belmont Report, created because of the National Research Act of 1974, lays out the ethical principles that should guide how medical/biological/behavioral research is carried out in humans. It was written by the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research and can be read in full here.
It is the document that requires participants to be fully informed of risks and benefits, to provide informed consent, and to voluntarily participate in a trial. It also requires those designing the trial to have respect for persons in the trial and to strive to “do no harm” and to ensure the anticipated risk-benefit balance of the intervention is appropriate.