The Supreme Court case Thompson, Master and Claimant of the Steamship Westmeath in 1919 revolved around a dispute over maritime law. The steamship Westmeath, owned by British citizens but chartered to an American company during World War I, was seized by U.S. authorities for alleged violation of trading with the enemy regulations. The ship's master and claimant, Thompson, argued that as it was under charter to an American firm at the time of seizure and therefore should not be subject to confiscation. However, the court ruled against him stating that ownership rather than possession determined nationality in such cases; thus making it liable for seizure since its owners were British subjects who had traded with Germany during wartime despite being leased out to an American entity when captured.

In the dissenting opinion for the case of Thompson, Master and Claimant of The Steamship Westmeath, Justice Oliver Wendell Holmes Jr. disagreed with the majority's ruling that a ship could be seized in international waters by U.S. authorities under Prohibition laws. He argued that such an interpretation extended American jurisdiction beyond its territorial limits, which was contrary to established principles of international law. Furthermore, he contended that if Congress had intended to authorize such seizures it would have done so explicitly rather than leaving it up to judicial interpretation. Therefore, he believed that the seizure was unlawful and should not have been upheld by the court.