United States v. Leon

The exclusionary rule requires that evidence illegally seized must be excluded from criminal trials. Leon was the target of police surveillance based on an anonymous informant’s tip. The police applied to a judge for a search warrant of Leon’s home based on the evidence from their surveillance. A judge issued the warrant and the police recovered large quantities of illegal drugs. Leon was indicted for violating federal drug laws. A judge concluded that the affidavit for the search warrant was insufficient ,it did not establish the probable cause necessary to issue the warrant. Thus, the evidence obtained under the warrant could not be introduced at Leon’s trial.


The deference accorded to a magistrate’s finding of probable cause does not preclude inquiry into the knowing or reckless falsity of the affidavit. Courts must insist that the magistrate perform his neutral and detached function and not serve merely as a rubber stamp for the police. Reviewing courts will not defer to a warrant based on an affidavit that does not provide the magistrate with a substantial basis for determining the existence of probable cause.

Brief Fact Summary:

Reasonable reliance upon an otherwise invalid search warrant does not render evidence obtained during the search inadmissible.