Clifford held to a limited interpretation of the Reconstruction amendments. He joined the majority in the Slaughter-House Cases (1873), which distinguished state and federal citizenship and held that the Fourteenth Amendment only protects the narrower rights of federal citizens. In "Hall v. DeCuir" (1877), Justice Clifford wrote a separate concurrence to uphold segregation on steamships, coining the phrase "equality is not identity." His concurrence may have foreshadowed the principle of "separate but equal" laid down after his death, in "Plessy v. Ferguson" (1893).