1945
After WWII, the Nuremberg trials exposed many horrifying "experiments" conducted by Nazi scientists and physicians. In response to these horrors, the international scientific and medical community devised the Nuremberg Code, a document that standardizes ethical research with human subjects. This code discusses ten basic tenets of ethical research with human subjects and is still used today as a guide for ethical research.
1972
The Tuskegee Syphilis Study was exposed in 1972 as a violation of the rights of human subjects. This study began in 1932 and its aim was to determine the long-term effects of syphilis. Poor black men in Alabama were targeted as subjects and were not told that they had syphilis, and they were denied treatment throughout the course of the study, even though treatment was available in the form of arsenic and bismuth before 1945 and penicillin afterward. News of this study cause public outrage and mistrust of the medical profession and researchers in general.
When the public learned of these violations, it was outraged and became distrustful of scientific research.