Thurgood Marshall's litigation of Brown v. Board of Education in 1952—the landmark case, decided in 1954, that made segregation illegal in United States public schools—was not his first case before the U.S. Supreme Court. Some legal scholars claim that the cases he presented to the court in the sixteen years before his successful argument for desegregation of public schools were necessary forerunners of that case: preliminary tests of legal strategies and early erosions of the foundations of discrimination against African Americans that paved the way for success in Brown.

When Marshall joined the legal staff of the National Association for the Advancement of Colored People (NAACP) in 1936, the organization was divided on how to proceed against the legal doctrine that for forty years had promoted "separate but equal" facilities for African Americans in educational institutions, in public transportation, and various other civic amenities. One approach was to emphasize that facilities were not in fact equal and to pursue litigation whose practical goal was the improvement both of opportunity for African Americans and of the facilities themselves. A second, more theoretical, approach was to argue that the concept of separate but equal facilities for the races was by its very nature impossible to fulfill, rendering the doctrine self-contradictory and hence legally unsound. Marshall correctly believed that the latter approach would eventually be the one to bring repeal of the doctrine, but felt it necessary in the short term to argue several cases using the former approach, in order to demonstrate the numerous ways in which segregation prevented real equality and thus to prepare the courts to recognize the validity of the theoretical argument.

While Marshall enjoyed several successes arguing for the equalization of facilities and opportunities in such areas as voting practices and accommodations for graduate students at public universities, it would be twelve years before he evolved a strategy for arguing against pervasive discriminatory practices that enabled him to make the leap from individual instances of inequality to the broader social argument needed to later invalidate "separate but equal." In 1948, Marshall litigated Shelley v. Kraemer, in which he convinced the court to outlaw housing discrimination practiced by private parties. Although the court had previously supported such practices implicitly under a doctrine that excused private dealings from the legal requirement for equal protection of citizens under law, Marshall presented sociological data demonstrating that, in sum and over time, these individual transactions constituted a pattern of insupportable discrimination. Marshall later used this strategy when arguing against individual schools' enrollment restrictions in Brown; scholars argue that his successful use of the strategy in Shelley prepared the court to accept such data as convincing evidence for finding "separate but equal" insupportable on its face.