Plessy v. Ferguson
The State of Louisiana passed a law saying that whites and blacks had to ride in different cars on trains, but required that the train cars be "equal."  Homer Plessy, who was one-eighth black (meaning that one of his eight great-grandparents was black) was arrested for riding in a whites-only car.  He challenged the  Louisiana law, saying it was against the United States Constitution. Plessy argued that the state law which required East Louisiana Railroad to segregate trains had denied him his rights under the Thirteenth and Fourteenth Amendments to the United States Constitution.