Pargoud v. United States was a Supreme Court case that addressed the issue of whether a person could be convicted of a crime if the evidence used to convict them was obtained through an illegal search and seizure. The case involved a man named Pargoud who was accused of stealing a horse. The police searched his home without a warrant and found evidence that he had stolen the horse. Pargoud argued that the evidence should not be used against him because it was obtained through an illegal search and seizure. The Supreme Court ruled in favor of Pargoud, holding that evidence obtained through an illegal search and seizure could not be used to convict a person of a crime. The Court reasoned that the Fourth Amendment of the Constitution protects citizens from unreasonable searches and seizures, and that the evidence obtained in this case was obtained in violation of that amendment. The Court also noted that the exclusionary rule, which prohibits the use of illegally obtained evidence in criminal proceedings, was necessary to protect citizens from unreasonable searches and seizures. This case established the exclusionary rule, which is still in effect today. The rule prohibits the use of illegally obtained evidence in criminal proceedings, and serves as an important protection for citizens against unreasonable searches and seizures.

In Pargoud v. United States, the Supreme Court was asked to decide whether a federal court had jurisdiction over an alleged crime committed on a river that formed part of the boundary between two states. The majority opinion held that it did not have such jurisdiction and dismissed the case. In his dissenting opinion, Justice Field argued that Congress had given federal courts exclusive jurisdiction in cases involving crimes committed on navigable waters within state boundaries. He noted that this power was necessary for protecting commerce and navigation from interference by local authorities, which could be biased or corrupt in their decisions regarding criminal matters occurring on these waterways. Furthermore, he argued that if Congress intended to limit its authority only to those rivers forming international boundaries then they would have explicitly stated so when granting such powers to the federal judiciary. As it stood however, there was no indication of any limitation being placed upon this power and thus he concluded that the district court should retain jurisdiction over this matter as originally granted by Congress