Plessy v. ferguson was a landmark 1896 u. s. supreme court decision that upheld the constitutionality of racial segregation under the "separate but equal" doctrine. the case stemmed from an 1892 incident in which african-american train passenger homer plessy refused to sit in a car for blacks. rejecting plessy’s argument that his constitutional rights were violated, the supreme court ruled that a law that "implies merely a legal distinction" between whites and blacks was not unconstitutional. as a result, restrictive jim crow legislation and separate public accommodations based on race became commonplace.