Under Marshall's leadership, the LDF played a crucial role in fighting segregation and discrimination against African Americans through litigation, advocacy, and public education. The organization brought groundbreaking cases to the Supreme Court, including Brown v. Board of Education (1954), which declared segregation in public schools to be unconstitutional. Marshall's leadership and legal expertise were instrumental in shaping the LDF's success in advancing the civil rights movement and achieving significant victories for racial justice and equality in the United States.