Even though slavery was abolished after the Civil War, Southern States continued to treat African Americans differently.
Governments within the southern states passed Jim Crow laws which prohibited blacks from using the same public accommodations as the whites. Louisiana passed the Separate Car Act(1890).
This act justified that separate accommodations for blacks and whites on railroad cars was within the law as long as the accommodations were equal in quality.
A group of both white and black activists from New Orleans organized the Citizen's Committee to Test the Separate Car Act to challenge the constitutionality of the Separate Car Law.
The organization raised money to hire a lawyer to defend them. When Albion W. Tourgee was approached, he agreed to help at no cost to the Citizen's Committee. The group found Homer A. Plessy, who was 1 eighth black and 7 eighth white, to deliberately break the segregation ruling. Although Plessy could pass as white, he announced that he had an African American ancestor. He was arrested on June 7, 1892 and his case reached the U.S. Supreme Court in 1896.
In a majority decision, Justice Henry Brown handed down the verdict that the Louisiana Separate Car Act did not violate the 13th Amendment nor did it violate the 14th Amendment of the Constitution. The reasoning was that the case did not involve the act of enslaving of Homer Plessy(13th) and the 14th Amendment was not violated because was created only for the right of African Americans to vote and serve on juries. It did not protect the social rights of African Americans.
"we cannot say that a law which authorizes or even requires the separation of the two races in public conveyances is unreasonable, or more obnoxious to the Fourteenth amendment than the acts of Congress requiring separate schools for colored children in the District of Columbia"
"...the assumption that the enforced separation of the two races stamps the colored race with a badge of inferiority.....(is) solely because the colored race chooses to put that construction upon it"As a result of this ruling Homer Plessy had to pay the fine. The ruling of Plessy v. Ferguson also served as the legal justification for racial segregation within the public sphere ultimately creating a racial caste society. There would continue to be segregation for over 50 years, until Brown v. Board of Education (1954) over turned the decision.
http://www.bgsu.edu/departments/acs/1890s/plessy/plessy.html