Congress passed a law during a 'War' with France. The law authorized the navy to seize vessels or cargoes apparently, as well as really, American and bound or sailing to any French port. The president authorized D to intercept any suspected American ship sailing to or from a French port. The Flying-Fish a Danish vessel having on board Danish and neutral property, was captured on the 2d of December 1799, on a voyage from Jeremie to St. Thomas's, by the United States frigate Boston, commanded by D, and brought into the port of Boston, where she was libelled as an American vessel that had violated the non-intercourse law. D believed that the vessel was of American origin and in violation of the non-intercourse law. The judge determined that the vessel was not American and was on a voyage from, not to a French port. The judge directed a restoration of the vessel and cargo as neutral property but refused to award damages for because there was probable cause to suspect the vessel to be American. The circuit court reversed because the Flying-Fish was on a voyage from, not to, a French port, and was therefore not liable to capture on the high seas. D was thus liable for trespass. D appealed, and the Supreme Court granted certiorari.