In Plessy v. Ferguson the Supreme Court interpreted the 14th Amendment very strictly. The 14th Amendment says, among other things, that no state may
deny to any person within its jurisdiction the equal protection of the laws.
In Plessy the Supreme Court showed that it believed that there was very little a state could do that would actually constitute a denial of equal protection.
In this case, the Court said that it was perfectly acceptable to have laws that segregated blacks and whites. It said that a Louisiana law that required blacks and whites to sit in separate cars did not “destroy” the legal equality of the two races. Instead, it simply recognized the fact that the two races were not, and never could be, socially equal. It is hard to imagine what sort of laws would have violated the 14th Amendment under this interpretation.
This interpretation of the amendment hurt African Americans in at least two very important ways. First, it reinforced racism by putting a government stamp of approval on the idea that blacks were inferior to whites. It allowed states to segregate blacks in all sorts of insulting and humiliating ways. We continue to struggle today with the legacy of racism, racism which was strengthened by Plessy. Second, it helped to create conditions that hurt African Americans in more tangible ways. For example, Plessy made it clear that segregated schools were acceptable. While it said that accommodations had to be equal, no effort was made to actually ensure that black and white schools were equal. This meant that, for generations, African American children had to attend inferior segregated schools. This made it so that blacks were much less educated than whites. This seriously reduced the life chances of African Americans as a group.
In these ways, the very strict interpretation of the 14th Amendment, as seen in Plessy, did much to harm African Americans in the ensuing decades.