United States v. Thompson 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 used to convict them was obtained through an illegal search and seizure. The case involved a man named Thompson 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 ruled that the evidence obtained through the illegal search and seizure was inadmissible in court and that Thompson could not be convicted on the basis of it. The Court held that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures and that any evidence obtained through an illegal search and seizure is inadmissible in court. This ruling established the exclusionary rule, which states that any evidence obtained through an illegal search and seizure is inadmissible in court. The ruling in United States v. Thompson was an important step in protecting citizens from unreasonable searches and seizures and in ensuring that the Fourth Amendment is upheld. The exclusionary rule established by this case has been used in many subsequent cases to protect citizens from unreasonable searches and seizures.

In United States v. Thompson, the Supreme Court was tasked with determining whether a defendant could be convicted of an offense without being present in court for his trial. The majority opinion held that the defendant had waived his right to be present and thus could be tried in absentia. Justice Field dissented from this decision, arguing that it violated both due process and common law principles which require defendants to appear at their own trials so they can challenge any evidence presented against them or make other necessary objections. He argued that allowing a conviction without presence would open up too many opportunities for abuse by prosecutors who might use false testimony or withhold exculpatory evidence if there is no one to object on behalf of the accused person. Furthermore, he noted that such convictions are not only unjust but also unconstitutional as they violate the Sixth Amendment's guarantee of a fair trial before impartial jurors and deprive individuals of their liberty without due process of law guaranteed by the Fifth Amendment.