United States v. Leon

Following is the case brief for United States v. Leon, United States Supreme Court, (1984)

Case summary for United States v. Leon:

  • Police officers executed a facially valid search warrant unveiling evidence that was later introduced at trial.
  • The warrant was later determined to lack probable cause.
  • Leon, along with others, moved to suppress the evidence claiming introduction of the evidence would violate their Fourth Amendment rights.
  • The Court held that so long as the warrant was facially valid and the officers reasonable relied upon the warrant, the exclusionary rule does not apply because the police did not act improperly.

United States v. Leon Case Brief

Statement of the facts:

After receiving a tip from a confidential informant, police began a drug trafficking investigation based upon the information provided. The information alleged that two men were selling drugs from their residence. Police then requested a warrant to search the suspects’ homes and automobiles, based on the relevant information unveiled from the investigation. In response, a facially sound warrant was issued. After the police executed the warrant, the accused filed motions to suppress the evidence discovered from the search, alleging that the affidavit failed to establish probable cause.

Procedural History:

The District court found in part for Leon, along with the others, granting their motions to suppress due to the lack of the warrant’s probable cause. The court of appeal’s affirmed the lower court’s decision. The government then appealed to the United States Supreme Court.

Rule of Law or Legal Principle Applied:

Evidence gathered based on the reasonable reliance of a facially valid warrant is admissible and does not violate the Fourth Amendment.

Issue and Holding:

Whether evidence obtained as a result of reasonable reliance on a search warrant that is later determined to be invalid is admissible at trial? Yes.


The Supreme Court reversed the decision of the district court and the appellate court.


  • The Court held that when evidence is obtained through the execution of a facially valid warrant, later deemed invalid, the evidence does not need to be suppressed in a subsequent trial.

The purpose of the Fourth Amendment is to protect people from unreasonable searches and seizures by the government. Unlike the Fourth Amendment, the exclusionary rule is a judicial remedy. The rule is intended to prevent the police from infringing on Fourth Amendment rights by prohibiting the introduction of dirty evidence.

Although an individual’s constitutional rights are prioritized over efficient law enforcement, officers can reasonably rely on a facially valid search warrant. Relying reasonably on a facially valid search warrant does not deter improper police conduct because there is no improper conduct to deter.

The Court held that in order to properly exclude evidence, the social cost of exclusion must outweigh Fourth Amendment violations and the evidence remain admissible for trial purposes. In addition, the exclusionary rule’s purpose is to deter the police from unconstitutional action, not judges.

In the event an officer should or actually does know that the magistrate issuing a warrant has been misled, or an affidavit is lacking in probable cause to the degree that an officer could not reasonably rely on it, the evidence must be excluded. However, that is not the case here. The court found that the police reasonably relied on a warrant that was facially valid and the evidence is admissible despite the fact that the warrant was later held to be invalid.

Concurring or Dissenting opinion:

Dissenting (Brennan):

The Court’s decision is inconsistent with Fourth Amendment protections against search and seizures. The Fourth Amendment itself, in addition to the exclusionary rule, prohibits the use of illegally obtained evidence from being used at trial.

The evidence obtained in “reasonable reliance on a warrant” later deemed invalid should still be excluded  because failing to do so will result in overlooking the requirements to provide probable cause in the affidavit and review the warrant when issued.

Dissenting (Stevens):

The intent behind the creation of the Fourth Amendment is to protect people from unreasonable warrants that are not initially established by probable cause.  The Majority’s holding that the officer’s reasonable reliance on a facially valid warrant is inevitably appropriate, is not constitutional.


This case set out the rule that evidence seized based upon a “facially valid” warrant, is admissible even if the warrant was later held to lack probable cause. Admission of evidence obtained by such a warrant that is reasonably relied upon by officers does not violate the accused’s Fourth Amendment right.

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