The Sloop Active v. The United States was a case heard by the Supreme Court in 1812 that dealt with the issue of whether or not an American vessel could be seized and condemned as a prize of war without violating its rights under international law. At issue was whether or not the seizure violated Article 3, Section 9 of the Constitution which states that no "Bill of Attainder" shall be passed. The court ultimately held that it did violate this provision because it constituted an act of attainder against a particular individual (the owner) rather than being applied to all vessels equally regardless of ownership. Furthermore, they found that such seizures were illegal under international law since they had been made without due process and thus violated both natural justice and principles established by treaties between nations.

In the case of The Sloop Active v. The United States, Chief Justice Marshall delivered a dissenting opinion in which he argued that the district court had no jurisdiction to hear the case because it was not within their power to decide on matters concerning maritime law or admiralty cases. He further stated that Congress had exclusive authority over such matters and thus any decision made by the district court would be void as they lacked proper jurisdiction. Additionally, Marshall noted that even if there were some legal basis for allowing them to make a ruling on this matter, it should have been done with caution due to its complexity and importance. Ultimately, he concluded that since Congress has sole authority over maritime law and admiralty cases, any decision made by the district court was invalid as they did not possess sufficient powers or knowledge necessary for making such decisions.