Louisville, Kentucky's 1914 ordinance required “the use of separate blocks, for residence ... by white people and colored people, respectively.” The Louisville and national NAACP, contesting “the racial zoning movement” (Silver, 1997, p. 25), counseled William Warley, a black postal worker who contracted to buy property in a white area from realtor Charles Buchanan. The state Court of Appeals ruled against Warley.

But the US Supreme Court unanimously rejected that ruling. It judged the ordinance unconstitutional as it “destroyed the right of the individual to acquire, enjoy, and dispose of his property” and avoided the “due process” clause of the Fourteenth Amendment. Reviewing “separate but equal,” it concluded that racially segregated residential zones “exceeded the limitations imposed by the Amendment” (Buchanan v. Warley, 1917). Residential ordinances segregating blacks, therefore, were not valid. This gave the NAACP a major victory, although restrictive covenants in deeds to segregate housing would follow.