Plessy v. Ferguson, argued on April 13, 1896, and decided on May 18, 1896, is probably best known for giving the United States the “separate but equal” doctrine. The case probably ranks close to Dred Scott v. Sandford (1857) as one of the most infl uential and thoroughly repudiated cases the Supreme Court has ever decided. The majority opinion was written by Justice Henry Billings Brown of Massachusetts, and it gained the assent of six additional justices. That opinion provided a legal imprimatur to segregation and the Jim Crow system of laws that fl ourished from the late nineteenth century through much of the twentieth century. Plessy held that notwithstanding the Reconstruction Amendments (the Thirteenth, Fourteenth, and Fifteenth Amendments), which were passed in the wake of the Civil War to grant equal citizenship to African Americans and promised the equal protection of the laws to all persons, the United States Constitution allowed states to segregate their black and white citizens when traveling on intrastate railroads. The separate but equal doctrine was applied to more than just railroads and supported segregation until it was largely repudiated, though not explicitly overruled, in Brown v. Board of Education of Topeka (1954).