United States v. Trammel
In United States v. Trammel, 445 U.S. 40 (1980), the U.S. Supreme Court eliminated the "marital unity" privilege in federal court that protected a defendant against adverse testimony by his spouse. At common law, the defendant had the right to object to calling his spouse to the witness stand to testify against him.
The Court held that someone accused of spying could not be convicted based on the testimony of the spouse.
Chief Justice Warren Burger wrote the opinion for a unanimous court (with one concurrence), modifying the precedent of Hawkins v. United States, 358 U.S. 74 (1958), that had barred the testimony of one spouse against the other unless both consent.