were civil rights activists who rode interstate buses into the segregated southern United States in 1961 and following years to test the United States Supreme Court decisions Boynton v. Virginia (1960) and Irene Morgan v. Commonwealth of Virginia (1946). …
Boynton outlawed racial segregation in the restaurants and waiting rooms in terminals serving buses that crossed state lines. Five years prior to the Boynton ruling, the Interstate Commerce Commission had issued a ruling in Sarah Keys v. Carolina Coach Company that had explicitly denounced the Plessy v. Ferguson doctrine of separate but equal in interstate bus travel. The ICC failed to enforce its ruling, and Jim Crow travel laws remained in force throughout the South.
The Freedom Riders challenged this status quo by riding various forms of public transportation in the South to challenge local laws or customs that enforced segregation. The Freedom Rides, and the violent reactions they provoked, bolstered the credibility of the American Civil Rights Movement. They called national attention to the disregard for the federal law and the local violence used to enforce segregation in the southern United States. Police arrested riders for trespassing, unlawful assembly, and violating state and local Jim Crow laws, along with other alleged offenses, but they often let white mobs attack them without intervention. (source)