United States v. Leon

Defendants must establish that either the magistrate issuing a search warrant, or the police officers that submit an affidavit establishing probable cause to obtain a search warrant, did not act in good faith to make evidence obtained under a warrant subsequently deemed defective inadmissible in court.

Public concern over the use of, and traffic in, illegal drugs reached new levels in the early 1980s. Perceptions of increases in violent crime linked to substance abuse led to political support for laws and policies making it easier for police to obtain convictions for drug traffickers. Amid this climate of popular support for aggressive law enforcement, Burbank, California police began investigating a suspected drug ring in August of 1981.

Police officers observed the activities of a group of individuals suspected of trafficking in drugs, and in due course applied to a neutral magistrate for a warrant to search their residences and automobiles. The warrant application was reviewed by a number of deputy district attorneys, and the warrant was granted by a state court judge. In the ensuing search, large quantities of drugs were recovered.

The case continued to district court, where an evidentiary hearing concluded that the officers' affidavit based on initial surveillance of the respondents was insufficient to establish probable cause, and that on this basis the search warrant used was invalid. This ruling was upheld on appeal by the state court of appeals, whereupon the government petitioned for certiorari on the question of "whether the Fourth Amendment exclusionary rule should be modified so as not to bar the admission of evidence seized in reasonable, good-faith reliance on a search warrant that is subsequently held to be defective." The Supreme Court agreed to hear the case, and arguments were presented on 17 January 1984.

Attorneys for Leon argued that the Fourth Amendment should be interpreted to preclude the use of evidence obtained under a defective warrant in a court of law. The government countered that the use of a warrant granted in good faith by neutral magistrates, and found to be defective only after the fact, should not constitute an impediment to law enforcement.

The Court overturned the judgement of the court of appeals by a vote of 6-3, allowing evidence obtained under the defective warrant to be used in court. Justice White delivered the Court's opinion. Central to the Court's thinking was the fact that the government did not ask for review of the lower courts' determinations that the search warrant was unsupported by probable cause, but rather for a ruling on the pliability of the Fourth Amendment exclusionary rule:

Although it undoubtedly is within our power to consider the question whether probable cause existed . . . that question has neither been briefed nor argued . . . and it is also within our authority, which we choose to exercise, to take the case as it comes to us.

The Court also made it clear that it believed the lower court decisions in this case to have been correct given the interpretation of the Fourth Amendment then in effect, stating that "the Court of Appeals understandably declined to adopt a modification of the Fourth Amendment exclusionary rule that this Court had not previously sanctioned." Finally, the Court ruled that the Fourth Amendment's intent would rarely be served by warrants invalidated after the fact, and that a modification of the amendment's interpretation should be allowed, as follows:

In the absence of an allegation that the magistrate abandoned his detached and neutral role, suppression is appropriate only if the officers were dishonest or reckless in preparing their affidavit or could not have harbored an objectively reasonable belief in the existence of probable cause.

Justices Brennan, Marshall, and Stevens dissented from the decision. Brennan and Marshall argued that evidence obtained under a defective warrant is always legally inadmissible, regardless of when the warrant is judged to be defective. Stevens offered that without probable cause all searches are unreasonable and therefore prohibited by the Fourth Amendment.

United States v. Leon marked a fundamental shift in the interpretation of the U.S. Constitution. By putting the onus of proof on defendants wishing to invalidate evidence obtained under defective search warrants, the Court radically altered the traditional interpretation of the Fourth Amendment and greatly increased the capabilities of law enforcement agencies at the expense of the rights of the individual.