One of the clearest ethical violations in the history of medical science has come to be known as

The correct answer is Tuskegee syphilis experiment

This was an experiment by the US government where they pretended to give free health care to African-American people in Alabama but were in reality observing how syphilis would develop when untreated and this lasted for over 40 years before a whistle-blower manged to inform the public on what the government was doing.