The ruling in plessy v. Ferguson in 1896 established

"separate but equal"

Explanation:

provided the legal justification for the expansion of segregation in America

Under the new ruling, the Equal Protection Clause of the 14thAmendment permitted the separation of people based upon race (or any other factor) as long as the facilities or opportunities that were being offered to one were roughly equal to what was being offered to the other.

This ability of the states to now pass segregation laws began to permeate throughout southern society and ushered in a more expansive approach to racial segregation.