The Supreme Court case of L'Amoureaux v. The Luminary was a dispute over the ownership of a ship called "The Luminary". Claimant, L'Amoureaux, argued that he had purchased the vessel from its former owner and thus held title to it. However, defendant maintained that they were in possession of the vessel prior to any sale by its previous owner and therefore should be considered rightful owners. After hearing both sides’ arguments, Chief Justice Marshall delivered an opinion for the court which found in favor of claimant L'Amoureaux on grounds that his purchase was valid under maritime law as long as there is no evidence showing otherwise. Furthermore, since defendant failed to provide such proof during trial proceedings their claim could not stand up against claimant's legal right to own The Luminary according

In The Luminary, L'Amoureaux v. United States, the Supreme Court was asked to decide whether a French vessel had been lawfully captured by an American privateer during the War of 1812. Chief Justice Marshall wrote for the majority that since France and America were not at war when the capture occurred, it could not be considered lawful under international law. However, Justice Johnson dissented from this opinion on two grounds: firstly, he argued that Congress had declared war against Britain before France joined in; secondly, he maintained that even if there was no formal declaration of war between America and France at the time of capture then "the state of actual hostility" should have been sufficient to render it legal according to international law principles. He concluded his dissent with a warning about how such decisions would affect future captures made by privateers in similar circumstances - namely that they may be found liable for damages as a result if their actions are later deemed unlawful due to lack of proper authority or jurisdiction.