Moore v. United States was a United States Supreme Court case that dealt with the issue of whether a defendant could be convicted of a crime if the evidence presented was obtained through an illegal search and seizure. The case involved a man named Moore who was convicted of receiving stolen goods. The evidence used to convict him was obtained through a search of his home without a warrant. Moore argued that the evidence should not be used against him because it was obtained illegally. The Supreme Court ruled in favor of Moore, holding that the evidence obtained through the illegal search and seizure was inadmissible in court. The Court reasoned that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures, and that the evidence obtained through the illegal search and seizure was in violation of this amendment. The Court also held that the exclusionary rule applied in this case, meaning that any evidence obtained through an illegal search and seizure could not be used in court. This case established an important precedent in criminal law, as it established the exclusionary rule and made it clear that evidence obtained through an illegal search and seizure could not be used in court. This case also established the importance of the Fourth Amendment in protecting citizens from unreasonable searches and seizures.

Justice Field delivered the dissenting opinion in Moore v. United States, arguing that Congress did not have the power to pass a law which would allow for an appeal from a decision of the Court of Claims. He argued that appeals were only allowed when specifically authorized by statute and no such authorization had been given in this case. Furthermore, he noted that even if Congress had intended to grant an appeal it could not do so without violating Article III of the Constitution which states "the judicial Power shall extend...to all Cases...arising under this Constitution." As there was no constitutional basis for allowing an appeal from a decision made by the Court of Claims, Justice Field concluded that any attempt by Congress to do so would be unconstitutional and void.