In the 1964 case McLaughlin v. Florida, the U.S. Supreme Court ruled that a Florida statute prohibiting an unmarried interracial couple from habitually living in and occupying the same room at night was unconstitutional. The appellants were a black man and white woman who had been convicted under this law for cohabitating while not being married to each other. They argued that their convictions violated both the Equal Protection Clause of Fourteenth Amendment because it discriminated on basis of race, as well as their right to privacy implicit in Ninth Amendment's reservation of rights to people. The court unanimously agreed with them on former ground but did not address latter argument about right to privacy. It held that there was no rational state interest served by such racial classification which could justify its infringement upon individual rights guaranteed by Constitution; therefore, it violated equal protection clause.

In the dissenting opinion for McLaughlin v. Florida, Justice Harlan argued that the state had a legitimate interest in preserving public decency and order, which could justify laws against interracial cohabitation. He believed that it was not within the Supreme Court's jurisdiction to question or interfere with these local regulations unless they were clearly irrational or arbitrary. Furthermore, he contended that such laws did not necessarily imply racial discrimination since they applied equally to all races involved in an interracial relationship. Therefore, according to him, there was no violation of equal protection under law as guaranteed by the Fourteenth Amendment. This perspective emphasized respect for states' rights and cautioned against judicial overreach into matters traditionally regulated at a local level.