In Wyatt v. United States (1959), the Supreme Court ruled on a case involving the interpretation of Rule 41(e) of the Federal Rules of Criminal Procedure, which pertains to motions for return and suppression of evidence. The appellant, Wyatt, was convicted for violating federal narcotics laws based on evidence obtained through a warrantless search by law enforcement officers who had probable cause but did not secure a warrant due to exigent circumstances. On appeal, Wyatt argued that his motion to suppress this evidence should have been granted because it was unlawfully seized during an unreasonable search in violation of his Fourth Amendment rights. The Supreme Court held that while Rule 41(e) does provide grounds for suppressing illegally obtained evidence if "the property was illegally seized without warrant," it does not require suppression when there is no showing that such illegal seizure prejudiced the defendant's case or violated their constitutional rights. In other words, even though police may have technically violated procedure by failing to obtain a warrant before conducting their search under exigent circumstances, this alone would not necessarily render any resulting trial unfair or unconstitutional unless it also resulted in some specific harm or prejudice against the defendant.

In the dissenting opinion for Wyatt v. United States, Justice Brennan disagreed with the majority's decision to uphold a conviction based on evidence obtained through an allegedly illegal search and seizure. He argued that this violated the Fourth Amendment rights of the defendant, which protect against unreasonable searches and seizures. Brennan contended that by allowing such evidence to be used in court, it effectively condones police misconduct and undermines citizens' constitutional protections. Furthermore, he criticized the majority's reliance on Rabinowitz case as precedent because its broad interpretation of "reasonable" search was inconsistent with previous rulings like Trupiano case which required both probable cause and exigent circumstances for warrantless searches to be considered reasonable.