In Wolfle v. United States, the defendant was convicted for sharing secret government information with his wife through letters while he was in prison. The Supreme Court had to determine whether these letters were protected by marital privilege and thus could not be used as evidence against him. In a 5-4 decision, the court ruled that marital privilege did not apply because it only protects verbal communication between spouses, not written communication or documents shared between them. Therefore, the conviction stood since the letters were admissible as evidence of his crime.

In the dissenting opinion for Wolfle v. United States, Justice McReynolds argued that the majority's decision to uphold Wolfle's conviction was a violation of his Fourth Amendment rights against unreasonable searches and seizures. He contended that the letters used as evidence in this case were obtained through an illegal search by a postal inspector who opened and read them without obtaining a warrant or having probable cause to do so. Furthermore, he disagreed with the majority’s view that marital privilege did not apply in this situation because it only protects communications intended to be confidential; he believed all spousal communications should be protected regardless of their nature or content. In essence, Justice McReynolds felt strongly that upholding such convictions would set a dangerous precedent for future cases involving privacy rights and protections against unlawful searches.