Final answer:
The Brown v. Board of Education case in 1954 ruled against 'separate but equal' and mandated desegregation, but its implementation was complicated by resistance and the ambiguous 'all deliberate speed' instruction in the 1955 Brown II ruling.
Step-by-step explanation:
The pivotal Supreme Court case, Brown v. Board of Education, desegregation in public schools in 1954 by declaring state laws establishing separate schools for black and white students to be unconstitutional. The case addressed the flawed 'separate but equal' doctrine enshrined by Plessy v. Ferguson, and it marked a significant step forward for civil rights in the United States. Following this decision, the term 'all deliberate speed', introduced in the subsequent 1955 ruling known as Brown II, became contentious. It instructed the implementation of desegregation but was sufficiently vague to allow some states to delay taking action. Resistance to desegregation, such as the Southern Manifesto and state-level opposition, highlighted the complexities of implementing the Court's decision across a country deeply divided on the issue of race.