What principle was established by the case Plessy v. Ferguson?

The principle established by the case Plessy v. Ferguson is "Separate but equal." This landmark Supreme Court decision, issued in 1896, upheld the constitutionality of racial segregation laws for public facilities as long as the segregated facilities were deemed to be equal in quality. The case arose after Homer Plessy, who was of mixed race, was arrested for refusing to sit in a segregated railroad car. The Court ruled that the state law requiring separate railway cars for white and African American passengers did not violate the Equal Protection Clause of the 14th Amendment, effectively legitimizing state-sponsored segregation.

This ruling had far-reaching implications, as it provided a legal foundation for the widespread implementation of segregation across many areas of public life, including education, transportation, and other public services, under the claim that segregation could be maintained as long as the facilities were equal, even though in practice, they rarely were. This principle remained in effect until it was challenged and ultimately overturned by later Supreme Court decisions, most notably Brown v. Board of Education in 1954.