The Buchanan v. Warley case in 1917 was a landmark decision by the United States Supreme Court that addressed racial segregation in residential areas. The case arose when Charles H. Buchanan, a white man, sued William Warley, an African American man who had agreed to buy property from him but later refused because of a Louisville ordinance prohibiting blacks from occupying homes on blocks where the majority were whites and vice versa. The court ruled unanimously against this law as it interfered with the right to contract which is protected under the Fourteenth Amendment's Due Process Clause. This ruling marked one of the first instances where racial zoning laws were deemed unconstitutional by federal courts and set important precedents for future civil rights cases.

In the Buchanan v. Warley case of 1917, there was no dissenting opinion recorded as the decision was unanimous. The U.S Supreme Court ruled in favor of Buchanan, declaring that laws segregating neighborhoods by race were unconstitutional because they interfered with property rights protected under the Fourteenth Amendment's due process clause. This landmark ruling invalidated racial zoning ordinances and upheld an individual's right to sell property without state interference based on race or color.