Researchers struggle with ethical concerns when using humans as research subjects, for example when developing vaccines for human diseases. Modern cases of unethical treatment of humans as research subjects led to laws that require voluntary consent of the human subjects in research.
Beecher (1966) article "Ethics and clinical research" elucidated unethical treatment of human research subjects even at some of the most prestigious institutions and publications in the U.S.
Institutional Review Boards were created in 1974 by the National Commission to protect the rights and welfare of human research subjects.
More information is available from http://irb.ufl.edu/
According to the federal regulations (45 CFR 46 102.f) a Human Subject means a living individual about whom an investigator conducting research obtains: