Dred Scott was a slave who had been taken to northern states by his master. He sued for his freedom, but the Supreme Court refused to hear his case. The Dred Scott decision encouraged slaveholder's resistance to abolitionist activists.
They had mad settlement houses which helped women and children in poverty, which seems discriminatory to modern people.
I think that maybe people are saying different answers because there might have been many such laws. I will mention one example: the Diversity Visa Immigration: it means that people from Eastern Europe have a higher change of obtaining a visa due to a smaller population in the US than the western European Countries.