Patterson v. Hoa's Executrix was a United States Supreme Court case decided in 1867. The case involved a dispute between two parties over the ownership of a slave named Hoa. The plaintiff, Patterson, claimed that he had purchased Hoa from a third party and was the rightful owner. The defendant, Hoa's Executrix, argued that Hoa had been willed to her by Hoa's deceased owner and that Patterson had no legal claim to the slave. The Supreme Court ultimately sided with the defendant, ruling that Patterson had no legal claim to Hoa. The Court held that the will of Hoa's deceased owner was valid and that Patterson had no right to the slave. The Court also held that Patterson had failed to prove that he had purchased Hoa from the third party, and thus had no legal claim to the slave. This ruling established that the will of a deceased owner was binding and that any claims to the ownership of a slave must be proven in court.

In the case of Patterson v. Hoa's Executrix, the Supreme Court was tasked with determining whether a slave who had been emancipated in one state could be considered a free person when traveling to another state where slavery still existed. The majority opinion held that such an individual would remain enslaved and subject to all laws governing slaves in the second state. Justice Field dissented from this decision, arguing that it violated both natural law and fundamental principles of justice by denying freedom to someone who had already been legally freed elsewhere. He argued that no court should have jurisdiction over any matter involving enslavement or emancipation since these matters are beyond its authority as they involve personal liberty which is not within their power to regulate or control. Furthermore, he asserted that if states were allowed to re-enslave individuals previously freed elsewhere then there would be no incentive for them ever grant emancipation at all due to fear of having those decisions overturned by other states' courts