Soon after joining the Court, Warren presided over the case of "Brown v. Board of Education", which arose from the NAACP's legal challenge against Jim Crow laws. The Southern United States had implemented Jim Crow laws in aftermath of the Reconstruction Era to disenfranchise African Americans and segregate public schools and other institutions. In the 1896 case of "Plessy v. Ferguson", the Court had held that the Fourteenth Amendment did not prohibit segregation in public institutions if the institutions were "separate but equal." In the decades after "Plessy", the NAACP had won several incremental victories, but 17 states required the segregation of public schools by 1954. In 1951, the Vinson Court had begun hearing the NAACP's legal challenge to segregated school systems but had not rendered a decision when Warren took office.