Final answer:
The Plessy v. Ferguson decision in 1896 endorsed state-sanctioned racial segregation under the 'separate but equal' doctrine, guaranteeing states the right to maintain racially segregated institutions and public facilities until it was overturned in 1954 by Brown v. Board of Education.
Step-by-step explanation:
The Supreme Court case Plessy v. Ferguson in 1896 established the separate but equal doctrine which sanctioned racial segregation as long as the separate facilities were deemed equal. This landmark decision ratified by the court validated the practice of segregation based on race in public facilities and institutions throughout the United States, especially in the southern states. Moreover, the Plessy decision entrenched the Jim Crow laws that enforced separate accommodations and reinforced racial discrimination for decades until its principles were overturned in the 1954 Brown v. Board of Education case, which declared segregation in public schools unconstitutional.
As such, because of the Plessy v. Ferguson decision, states were guaranteed the right to implement racially segregated institutions and public facilities. This interpretation of the Fourteenth Amendment's equal protection clause meant that racial segregation did not violate the principles of equality under the law, as long as the facilities provided to each race were outwardly equivalent despite the persistent inequality in reality.