The United States v. John Arthur and Robert Patterson was a Supreme Court case in which the defendants were charged with violating the Neutrality Act of 1794 by supplying arms to France during their war with Great Britain. The court found that, while it was true that they had supplied arms to France, this did not constitute an offense under the Neutrality Act because there was no evidence that either defendant intended for those weapons to be used against any nation at peace with America. Furthermore, since neither defendant had taken any action contrary to American neutrality laws or treaties prior to providing these supplies, they could not be held liable for doing so afterwards. Ultimately, the court ruled in favor of both defendants and dismissed all charges against them on grounds of insufficient evidence.

In the United States v. John Arthur and Robert Patterson, the Supreme Court was asked to decide whether a federal court had jurisdiction over an indictment for robbery of goods from a vessel on navigable waters. The majority opinion held that such offenses were within the scope of admiralty law and thus subject to federal jurisdiction. However, Justice Johnson dissented from this decision, arguing that Congress had not given any authority in their statutes for such cases to be tried by federal courts; instead he argued that these types of crimes should be tried in state courts as they have traditionally been done so since colonial times. He further noted that if Congress wished to give exclusive power over maritime offenses then it would need to pass specific legislation granting them such authority - something which has yet to occur at this time.