The Legal Defense Fund (LDF) is a non-profit legal organization that was founded in 1940 by Thurgood Marshall, Charles Hamilton Houston, and other prominent civil rights attorneys. The LDF was established with the mission of fighting for racial justice and equality through the legal system.

One of the LDF's most famous cases was Brown v. Board of Education, a landmark Supreme Court case in 1954 that declared racial segregation in public schools unconstitutional. Thurgood Marshall, who was the LDF's first Director-Counsel, argued the case before the Supreme Court and played a pivotal role in achieving this historic ruling.

Throughout its history, the Legal Defense Fund has been involved in numerous other significant legal battles to combat discrimination and protect the rights of Black individuals in various areas such as housing, employment, voting rights, and criminal justice. The organization continues to be at the forefront of civil rights advocacy and litigation, and its work has had a lasting impact on shaping the legal landscape in the United States.