Which U.S. Supreme Court case established the 'separate but equal' doctrine?

Which U.S. Supreme Court case established the “separate but equal” doctrine? The answer is Plessy v. Ferguson.

Decided in 1896, the case involved Homer Plessy, a mixed-race New Orleanian who deliberately sat in a whites-only railroad car to challenge Louisiana’s Separate Car Act of 1890. The Supreme Court ruled 7–1 that state-mandated racial separation did not violate the Fourteenth Amendment as long as supposedly comparable facilities were provided.

In practice, facilities for Black Americans were rarely equal. The decision helped legitimize Jim Crow segregation across the South and influenced segregation in schools, transportation, restaurants, and other public facilities. Justice John Marshall Harlan’s dissent argued that the Constitution should not recognize racial classes.

A common mix-up is Brown v. Board of Education: that 1954 case rejected racial segregation in public schools and effectively undermined Plessy, rather than creating the doctrine. Plessy has never been explicitly overruled, but its constitutional rule is regarded as discredited.