Independent Source Doctrine

The independent source doctrine is an exception to the exclusionary rule in United States law permitting evidence first discovered through an unlawful search to be admitted anyway if it was also obtained through a later, lawful means genuinely separate from the illegal conduct. The Supreme Court set out its rationale in Nix v. Williams in 1984, holding that the interest in deterring unlawful police conduct must be balanced against the public interest in juries receiving all probative evidence, so that police are placed in neither a better nor a worse position than if the misconduct had never happened. The governing test comes from Murray v. United States in 1988: the doctrine applies only when the decision to seek a warrant was not prompted by what officers observed during the illegal entry, and when information from that entry was not given to the magistrate or did not influence the issuance of the warrant. A later case, State v. Boll in 2002, extended the doctrine to partially tainted warrant applications where the untainted information alone still establishes probable cause.