Homer Adolph Plessy was an American shoemaker and activist, who was the plaintiff in the United States Supreme Court decision Plessy v. Ferguson. He staged an act of civil disobedience to challenge one of Louisiana's racial segregation laws and bring a test case to force the U.S. Supreme Court to rule on the constitutionality of segregation laws. The Court decided against Plessy. The resulting "separate but equal" legal doctrine determined that state-mandated segregation did not violate the Fourteenth Amendment to the United States Constitution as long as the facilities provided for both black and white people were putatively "equal". The legal precedent set by Plessy v. Ferguson lasted into the mid-20th century, until a series of landmark Supreme Court decisions concerning segregation, beginning with Brown v. Board of Education in 1954.

Separate but equal was a legal doctrine in United States constitutional law, according to which racial segregation did not necessarily violate the Fourteenth Amendment to the United States Constitution, which nominally guaranteed "equal protection" under the law to all people. Under the doctrine, as long as the facilities provided to each race were equal, state and local governments could require that services, facilities, public accommodations, housing, medical care, education, employment, and transportation be segregated by race, which was already the case throughout the states of the former Confederacy. The phrase was derived from a Louisiana law of 1890, although the law actually used the phrase "equal but separate".