Answer:
a. Thurgood Marshall
b. Landmark case: Brown v. Board of Education in 1954
Step-by-step explanation:
Thurgood Marshall was the first African American to serve on the Supreme Court of the United States. Prior to his appointment to the Supreme Court, he worked as a lawyer for the National Association for the Advancement of Colored People (NAACP).
His landmark case as a lawyer was Brown v. Board of Education in 1954, which declared racial segregation in public schools unconstitutional. The case is widely recognized as a major step forward in civil rights in the United States, as it overturned the "separate but equal" doctrine established by the 1896 Plessy v. Ferguson case.
Marshall argued that segregation was inherently unequal and that it violated the 14th Amendment’s guarantee of equal protection under the law. The Supreme Court agreed and unanimously ruled in favor of Brown. Marshall’s victory in the case set a precedent for civil rights cases that followed and shaped the legal landscape of the United States for decades.