Baird v. United States was a United States Supreme Court case that addressed the issue of 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, Baird, who was charged with receiving stolen goods. The evidence used to convict Baird was obtained through a search and seizure that was conducted without a warrant. The Supreme Court held that the evidence obtained through the illegal search and seizure was inadmissible in court and that Baird could not be convicted on the basis of that evidence. 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 that 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 Baird v. United States established the precedent that evidence obtained through an illegal search and seizure is inadmissible in court and that defendants cannot be convicted on the basis of such evidence. 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 Baird v. United States, arguing that Congress had no authority to pass a law criminalizing the possession of obscene materials. He argued that obscenity was not within the scope of any power delegated to Congress by the Constitution and therefore it could not be made illegal under federal law. Furthermore, he asserted that even if such a power existed, it would still be unconstitutional because it violated an individual's right to privacy as protected by the First Amendment. Finally, Justice Field noted that while some states had laws prohibiting obscenity, those laws were passed before adoption of the Fourteenth Amendment and thus did not apply on a national level. In conclusion, Justice Field believed that Congress lacked both constitutional authority and justification for passing this particular legislation and should have left regulation of obscene material up to state governments or individuals themselves through their own moral standards rather than attempting to impose its own morality on all citizens nationwide.