Plessy v. Ferguson was a landmark U.S. Supreme Court case in 1896 that upheld the constitutionality of racial segregation under the “separate but equal” doctrine. The case involved Homer Plessy, a Black man who was arrested in Louisiana for sitting in a whites-only railroad car. Plessy argued that the state's Separate Car Act violated his rights under the 13th and 14th Amendments to the U.S. Constitution.

However, the Supreme Court ruled against Plessy, with Justice Henry Billings Brown writing the majority opinion. The Court held that segregation was legal as long as facilities were deemed to be "equal" for both Black and white individuals. This decision established the legal precedent for segregation and discrimination against African Americans for decades to come, leading to Jim Crow laws and institutionalized racism in the United States.

Plessy v. Ferguson was eventually overturned by the Supreme Court in 1954 in the case of Brown v. Board of Education, which declared that separate educational facilities were inherently unequal and violated the 14th Amendment's Equal Protection Clause.