In United States v. Thomas, the United States Supreme Court addressed 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 involved a defendant, Thomas, who was charged with receiving stolen goods. The goods were seized by a United States Marshal without a warrant. Thomas argued that the evidence should be excluded because it was obtained through an illegal search and seizure. The Court rejected this argument, holding that the evidence was admissible and that the defendant could be convicted. The Court reasoned that the Fourth Amendment does not protect against all unreasonable searches and seizures, but only those that are conducted without a warrant. Since the Marshal had acted without a warrant, the search and seizure were illegal. However, the Court held that the evidence was still admissible because the exclusionary rule, which prohibits the use of illegally obtained evidence, does not apply to criminal proceedings. The Court concluded that the evidence was admissible and that the defendant could be convicted. This decision established the principle that evidence obtained through an illegal search and seizure can be used in criminal proceedings.

In United States v. Thomas, the Supreme Court was tasked with determining whether a defendant who had been convicted of violating federal law could be tried in state court for the same offense. The majority opinion held that such double jeopardy did not apply to this case because it involved two separate sovereigns—the United States and the State of California—and thus, dual prosecutions were permissible. Justice Field dissented from this decision, arguing that allowing multiple prosecutions violated both common sense and justice as well as being contrary to established legal principles which prohibited double jeopardy under any circumstances. He argued that since Congress had adopted a single criminal code applicable throughout all states, there should be only one prosecution regardless of where it occurred; otherwise defendants would face an unfair risk of conviction due to repeated trials on identical charges by different governments. Ultimately he concluded that while each government may have its own laws governing certain offenses within their respective jurisdictions, they must still abide by constitutional protections against double jeopardy when prosecuting individuals for violations thereof.