Final answer:
The Plessy v. Ferguson case of 1896 upheld the racial segregation law under the 'separate but equal' doctrine, affirming legal racial discrimination until it was overturned by Brown v. Board of Education in 1954.
Step-by-step explanation:
The landmark Plessy v. Ferguson case of 1896 was a significant legal event in American history that dealt with the constitutionality of racial segregation. Homer Plessy, who was of mixed race, challenged the Louisiana segregation law after he was arrested for sitting in a Whites-only railroad car.
The heart of the case was whether the law violated the 14th Amendment, which guarantees equal protection under the law. However, the Supreme Court, in a decision of 7-1 with Justice John Marshall Harlan dissenting, upheld the segregation law under the notion of "separate but equal."
This ruling legalised de jure segregation and affirmed the continuing discriminatory practice of racial inequality in public accommodations in the United States.
The case cemented the doctrine of "separate but equal" legitimizing discrimination in public facilities, transportation, and schools for over half a century until the Brown v. Board of Education decision of 1954. This later case ruled that 'separate but equal' was inherently unequal in the context of public education, leading to the gradual dismantling of legally sanctioned racial segregation.