What was the US Supreme Court decision in US v Leon?

US v. Leon, (1984) established a "good faith" exception to the Fourth Amendment exclusionary rule that allows evidence seized under an invalid warrant to be used in court if the police acted in "good faith," but the warrant is later determined to be defective due to insufficient probable cause.


US v. Leon established the "good faith" exception to the exclusionary rule in Fourth Amendment search and seizure cases. The exclusionary rule forbid the use of evidence obtained in an illegal search and seizure from being used in court, and is intended to prevent unlawful police action.

A good faith exception occurs when police submit truthful information to a judge or magistrate who then errs by issuing a warrant without sufficient probable cause. The police then execute the warrant under the assumption that it's valid, acting in "good faith."

If the warrant is later declared invalid due to a neutral error on the part of the issuing judge, the evidence obtained in the search may still be used in court because the police acted in "good faith," and did not deliberately violate the defendant's Fourth Amendment rights. The Court held that the purpose of search and seizure laws was to deter unlawful police action, not to punish judicial error.

If the warrant was issued because police lied or presented false information, the exclusionary rule remains in effect.

Justice Byron White, who delivered the opinion of the Court, explained the reasoning behind the justices' decision:

"The Fourth Amendment contains no provision expressly precluding the use of evidence obtained in violation of its commands, and an examination of its origin and purposes makes clear that the use of fruits of a past unlawful search or seizure "work[s] no new Fourth Amendment wrong." United States v. Calandra, 414 U. S. 338, 414 U. S. 354 (1974). The wrong condemned by the Amendment is "fully accomplished" by the unlawful search or seizure itself, ibid., and the exclusionary rule is neither intended nor able to "cure the invasion of the defendant's rights which he has already suffered." Stone v. Powell, supra, at 428 U. S. 540 (WHITE, J., dissenting). The rule thus operates as "a judicially created remedy designed to safeguard Fourth Amendment rights generally through its deterrent effect, rather than a personal constitutional right of the party aggrieved.""

Case Citation:

United States v. Leon, 468 US 497 (1984)

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