Zafiro, Martinez, Garcia, and Soto (defendants) were suspected of drug distribution. Under Federal Rules of Criminal Procedure (FRCP) Rule 8(b), all four defendants were indicted and tried together. Each of the defendants claimed to be innocent and blamed the remaining codefendants. At trial, all four defendants moved for severance under Rule 14 on the grounds that their defenses were “mutually antagonistic.” The district court denied the motion, and the defendants were convicted. The defendants appealed. The court of appeals affirmed. The United States Supreme Court granted certiorari.