Plessy v. Ferguson was a landmark U.S. Supreme Court case that was decided in 1896. The case involved Homer Plessy, a Black man who was arrested for refusing to leave a whites-only railroad car in Louisiana. Plessy argued that the state's Separate Car Act, which required separate facilities for Black and white passengers on trains, violated the 13th and 14th Amendments to the U.S. Constitution.

The Supreme Court, in a 7-1 decision, upheld the constitutionality of segregation under the "separate but equal" doctrine. This ruling established the legal precedent for racial segregation in public facilities and institutions, paving the way for the Jim Crow laws that enforced segregation and discrimination against African Americans for decades.

The Plessy v. Ferguson decision had a significant impact on the civil rights movement in the United States, as it sanctioned racial segregation and discrimination in both the legal and social spheres. It wasn't until the landmark case of Brown v. Board of Education in 1954 that the "separate but equal" doctrine was overturned, marking a turning point in the fight for civil rights and racial equality in America.