Murray v. United States

The exclusionary rule prohibits the introduction into evidence, in a criminal prosecution, of tangible materials seized during an unlawful search, and of testimony concerning knowledge acquired during an unlawful search. The exclusionary rule also prohibits the introduction of evidence, both tangible and testimonial, that is the product of the unlawful search.

Neither of those events occurred here. The “independent source” doctrine allows evidence secured in connection with a violation of the Fourth Amendment to be admissible if that evidence was discovered through a source independent of the illegality.

The Court held this rule applies to evidence initially obtained during an independent lawful search as well as evidence that is discovered during an unlawful search but is later obtained independently from activities untainted by the illegality. The evidence here would be admissible if the second search, conducted with a search warrant, was a genuinely independent source of that evidence. If the agents’ decision to seek that warrant was prompted by what they saw during the illegal entry or if information obtained during that entry was presented to the reviewing magistrate, independence does not exist.