In Mitchell 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, Mitchell, who was charged with receiving stolen goods. The evidence used to convict Mitchell 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 Mitchell. 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 Mitchell 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 and has become an important part of Fourth Amendment jurisprudence.

Justice Field delivered the dissenting opinion in Mitchell v. United States, arguing that Congress had exceeded its authority under the Constitution by enacting a law which allowed for criminal prosecution of an individual who failed to pay taxes on income from illegal activities. He argued that such a law was not authorized by any clause in the Constitution and thus violated due process as it deprived individuals of their property without just compensation or due process of law. Furthermore, he argued that this type of legislation could lead to arbitrary enforcement and would be difficult to enforce fairly since it required proof beyond reasonable doubt regarding whether or not someone had engaged in illegal activity before they were taxed on their income. Justice Field concluded his dissent by stating that if Congress wanted to impose taxes on income derived from unlawful activities then they should do so through constitutional means rather than attempting to pass laws outside those boundaries set forth in the document itself.