United States v. Demorant 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 at trial was obtained through an illegal search and seizure. The Court held that the evidence was admissible and that the defendant could be convicted. The case arose when the defendant, Demorant, was arrested for the possession of counterfeit money. The arresting officers had conducted a search of Demorant's home without a warrant, which was in violation of the Fourth Amendment. Demorant argued that the evidence obtained during the search should be excluded from trial because it was obtained illegally. The Supreme Court disagreed and held that the evidence was admissible. The Court reasoned that the exclusionary rule, which prohibits the use of illegally obtained evidence, was not applicable in this case because the officers had acted in good faith and had not acted with the intent to violate the Fourth Amendment. The Court also noted that the exclusionary rule was intended to deter police misconduct, not to punish innocent officers. The Court's decision in United States v. Demorant established that evidence obtained through an illegal search and seizure can be used in a criminal trial, provided that the officers acted in good faith and without the intent to violate the Fourth Amendment. This decision has been cited in numerous subsequent cases and has become an important precedent in Fourth Amendment jurisprudence.

In United States v. Demorant, the Supreme Court was tasked with determining whether a defendant could be convicted of aiding and abetting another person in committing an offense against the United States when that other person had already been acquitted of said offense. The majority opinion held that such conviction was permissible under the law, but Justice Field dissented from this ruling. He argued that it would be unjust to allow someone to be found guilty for aiding and abetting a crime if the principal actor had already been acquitted by a jury. Furthermore, he noted that allowing such convictions would create uncertainty as to what evidence is necessary for conviction since one cannot know beforehand which party will ultimately prevail at trial; thus making it difficult for defendants to prepare their defense accordingly. In conclusion, Justice Field believed that convicting someone on these grounds violated due process rights guaranteed by both federal and state constitutions because it allowed guilt or innocence to depend upon events outside of court proceedings rather than solely on those within them.