Locke v. New Orleans was a United States Supreme Court case that was decided in 1866. The case involved a dispute between the City of New Orleans and a group of African-American citizens who had been denied the right to purchase property in the city. The African-American citizens argued that the city's ordinance, which prohibited them from purchasing property, violated the Thirteenth Amendment of the United States Constitution, which abolished slavery. The Supreme Court agreed with the African-American citizens, ruling that the ordinance was unconstitutional and that the city had violated the Thirteenth Amendment. The Court also held that the ordinance was a form of racial discrimination and that it violated the Equal Protection Clause of the Fourteenth Amendment. The Court's decision was a major victory for African-American citizens, as it established that they had the same rights as other citizens to purchase property. The decision also set a precedent for future cases involving racial discrimination.

In Locke v. New Orleans, the Supreme Court was asked to decide whether a Louisiana law that imposed a tax on all persons engaged in selling goods violated the Thirteenth Amendment of the United States Constitution. The majority opinion held that it did not violate the amendment because it applied equally to both citizens and non-citizens alike. Justice Field dissented from this decision, arguing that even though the law may have been applied equally to everyone, its purpose was still discriminatory as it targeted those who were engaging in commerce with African Americans or freedmen specifically. He argued that such laws should be considered unconstitutional under Section 1 of the Thirteenth Amendment which prohibits any form of involuntary servitude or peonage except for punishment for crime whereof one has been duly convicted. Furthermore, he noted how these types of taxes could lead to further discrimination against African Americans by making them unable to engage in certain forms of economic activity due their inability pay such taxes without suffering financial hardship.