The landmark U.S. Supreme Court case that ruled racial segregation in public schools unconstitutional was Brown v. Board of Education, decided in 1954. This ruling was pivotal in challenging the legal basis for segregation, which had been entrenched in the earlier Plessy v. Ferguson decision of 1896 that upheld "separate but equal" facilities. The Brown case emphasized that segregated schools were inherently unequal, thereby violating the Equal Protection Clause of the Fourteenth Amendment. This decision galvanized the civil rights movement, leading to further actions aimed at dismantling segregation and promoting equality across various sectors of society.