Final answer:
De jure segregation refers to segregation enforced by law, which was the case for policies mandating racial segregation.
Step-by-step explanation:
De jure segregation refers to segregation that is enforced by law, while de facto segregation occurs without laws but because of other factors.
In the context of racial segregation, the policies mandating racial segregation were primarily established through de jure segregation. Jim Crow laws, which required segregated facilities for blacks and whites, were passed by many Southern states after the Civil War. These laws were later upheld by the Supreme Court in the 1896 Plessy v. Ferguson case, which stated that 'separate but equal' facilities were constitutional. It wasn't until the 1954 Brown v. Board of Education case that the Supreme Court declared that 'separate educational facilities are inherently unequal', effectively ending de jure segregation in the United States.