"The Tuskegee syphilis experiment was an infamous clinical study conducted between 1932 and 1972 by the U.S. Public Health Service to study the natural progression of untreated syphilis in rural African-American men in Alabama. They were told that they were receiving free health care from the U.S. government."
https://en.wikipedia.org/wiki/Tuskegee_syphilis_experiment
"The Tuskegee syphilis experiment was an infamous clinical study conducted between 1932 and 1972 by the U.S. Public Health Service to study the natural progression of untreated syphilis in rural African-American men in Alabama. They were told that they were receiving free health care from the U.S. government."