Because of these cases, and others like them, The National Commission for the Protection of Human Subjects in Biomedical and Behavioral Research was created by the federal government to establish the basic principles that should guide the ethical use of humans in research. In April, 1979 they published The Belmont Report.  It established the three tenets on which the current human subjects regulations are based:
Respect for Persons involves a recognition of the personal dignity and autonomy of individuals, and special protection of those persons with diminished autonomy.
Beneficence entails an obligation to protect persons from harm by maximizing anticipated benefits and minimizing possible risks of harm.
Justice requires that the benefits and burdens of research be distributed fairly.
Familiarity with this report and the ethical discussions it contains is key to the ethical use of people in research. 

In the twenty years since the Belmont Report was published, many new policies and regulations have been put in place.  Many of these have been in response to ethical violations that resulted in unacceptable risk to the participants of research.