Nix v. Williams, 467 U.S. 431 (1984), was a U.S. Supreme Court case that created an "inevitable discovery" exception to the exclusionary rule. The exclusionary rule makes most evidence gathered through violations of the Fourth Amendment to the United States Constitution, which protects against unreasonable search and seizure, inadmissible in criminal trials as "fruit of the poisonous tree". In Nix, the Court ruled that evidence that would inevitably have been discovered by law enforcement through legal means remained admissible.