The correct answers are
De jure is a Latin expression used in law and government to describe practices that are recognised in the legal system, even if they do not exist in practice. On the contrary, th de facto is used in law to describe situations that occur in practice but are not acknowledged by the law.
The Plessy v. Ferguson case led to the enactment of a landmark Supreme Court decision in 1896. Such decision allowed the proliferation of segregated schools and the constutionality of the "separate but equal" principle under the belief that, if facilities were equal in quality, such education system was not violating the equality of rights provision that had been guaranteed for all US citizens by the Reconstruction Amendments to the US Constitution.