The Fortuna case was a dispute between two parties over the ownership of a ship called the Fortuna. The claimants, Krause et al., argued that they had purchased and registered the vessel in Hamburg before it was seized by French authorities during Napoleon's wars. They further claimed that their rights to the vessel were protected under international law as well as U.S.-Hamburg treaties from 1799 and 1814. On appeal to the Supreme Court, Chief Justice Marshall ruled in favor of Krause et al., finding that their title to the ship had been established prior to its seizure by France and thus could not be taken away without compensation or due process of law. He also held that these protections extended even beyond war time, noting "the right which is acquired by purchase cannot be impaired either directly or indirectly." This decision set an important precedent for protecting private property rights against government interference both domestically and internationally.

In The Fortuna case, the Supreme Court was tasked with determining whether a vessel that had been captured by an enemy during wartime could be considered abandoned and therefore subject to salvage. A majority of justices ruled in favor of the claimants who sought salvage rights for their capture of the vessel, but Justice Johnson dissented from this opinion. He argued that since there was no evidence presented to prove abandonment or lack of ownership at the time when it was taken into possession by the claimants, they were not entitled to any compensation for salvaging it. Furthermore, he noted that even if such proof had been provided, it would have only established a prima facie right and still left open questions as to whether other parties may have held superior title over them. Ultimately then, Johnson concluded that without clear evidence establishing absolute abandonment or lack of ownership prior to its capture by those seeking salvage rights - which did not exist in this case - they should not receive any compensation for their efforts.