In Spencer v. United States, the Supreme Court of the United States was asked to decide whether a defendant 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 defendant, Spencer, who was charged with receiving stolen goods. The evidence used to convict him was obtained through a search of his home without a warrant. The Supreme Court held that the evidence obtained through the illegal search and seizure was inadmissible in court and could not be used to convict Spencer. 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 was inadmissible in court. The Court's decision in Spencer v. United States established the precedent that evidence obtained through an illegal search and seizure is inadmissible in court and cannot be used to convict a defendant. This decision has been cited in numerous cases since then and has become an important part of Fourth Amendment jurisprudence.

Justice Field delivered the dissenting opinion in Spencer v. United States, arguing that the Court should not have reversed its earlier decision in Ex Parte Siebold and held that Congress had exceeded its authority under Article I of the Constitution by enacting a law criminalizing certain acts related to elections. He argued that Congress has broad powers to regulate elections for federal offices, including those involving state officers, and noted that it was well established at common law for centuries before adoption of the Constitution. Furthermore, he maintained that there was no express prohibition on such legislation in any part of the Constitution or Bill of Rights; thus, if Congress had intended to limit its power over election laws it would have done so explicitly. Finally, Justice Field concluded his dissent by noting that even if one were to accept an implied limitation on congressional power over election laws as suggested by Chief Justice Waite's majority opinion—which he did not—the challenged statute still fell within permissible limits because it only regulated conduct which could be considered corrupt practices with respect to voting rights.