Otis Trammel (defendant) was charged with crimes related to the importation of heroin. His wife, Elizabeth, was also involved in the importation and agreed to testify against Otis in exchange for judicial leniency. Otis objected to Elizabeth’s testimony on the grounds of marital privilege. The district court determined that Elizabeth could testify to any act she observed during their marriage and any statement that was made in the presence of third parties. The court found Otis guilty. The court of appeals affirmed. The United States Supreme Court granted certiorari.