In Osborn v. United States (1966), the U.S. Supreme Court upheld a conviction based on evidence obtained through a wiretap placed by an informant, ruling that it did not violate the Fourth Amendment's protection against unreasonable searches and seizures. The case involved petitioner Robert E. Osborn who was convicted of attempting to bribe a federal Internal Revenue Service agent after conversations were recorded via an electronic device voluntarily worn by the agent during their meetings. In its decision, the court held that there was no intrusion since one party consented to record these conversations and therefore, no constitutional rights were violated in this process.

In the dissenting opinion for Osborn v. United States, Justice Hugo Black argued that the government's use of an undercover agent to entrap a defendant was unconstitutional. He believed that this method violated the defendant's Fifth Amendment rights against self-incrimination and his Sixth Amendment right to counsel. According to Justice Black, by using an undercover agent who acted as a confidant and advisor while secretly recording conversations for evidence, the government effectively denied Osborn access to legal advice during these critical stages of criminal proceedings. Furthermore, he contended that such tactics were inherently deceptive and constituted "dirty business" which should not be condoned in American courts of law.