Eugenics
But some of those who led the eugenics movement used it to justify racism and prejudice. They used eugenics as an excuse to pass laws which to restrict immigration from countries that they did not like, saying that the people in them were genetically "unfit". They also passed laws which said that people of different races could not get married to one another. Most importantly, they passed laws which said that people who were thought to have mental illness or mental disability could be sterilised against their will. Under these laws over 60,000 people were sterilised in the United States between 1907 and the 1970s.