United States v. Leon, 468 U.S. 897 (1984)

Fundamental Cases on the Fourth Amendment by Adam J. McKee

JUSTICE WHITE delivered the opinion of the Court.

This case presents the question whether the Fourth Amendment exclusionary rule should be modified so as not to bar the use in the prosecution’s case in chief of evidence obtained by officers acting in reasonable reliance on a search warrant issued by a detached and neutral magistrate but ultimately found to be unsupported by probable cause.  To resolve this question, we must consider once again the tension between the sometimes competing goals of, on the one hand, deterring official misconduct and removing inducements to unreasonable invasions of privacy and, on the other, establishing procedures under which criminal defendants are “acquitted or convicted on the basis of all the evidence which exposes the truth.”


In August, 1981, a confidential informant of unproven reliability informed an officer of the Burbank Police Department that two persons known to him as “Armando” and “Patsy” were selling large quantities of cocaine and methaqualone from their residence at 620 Price Drive in Burbank, Cal.  The informant also indicated that he had witnessed a sale of methaqualone by “Patsy” at the residence approximately five months earlier, and had observed at that time a shoebox containing a large amount of cash that belonged to “Patsy.”  He further declared that “Armando” and “Patsy” generally kept only small quantities of drugs at their residence and stored the remainder at another location in Burbank.

On the basis of this information, the Burbank police initiated an extensive investigation focusing first on the Price Drive residence and later on two other residences as well.  Cars parked at the Price Drive residence were determined to belong to respondents Armando Sanchez, who had previously been arrested for possession of marihuana, and Patsy Stewart, who had no criminal record.  During the course of the investigation, officers observed an automobile belonging to respondent Ricardo Del Castillo, who had previously been arrested for possession of 50 pounds of marihuana, arrive at the Price Drive residence.  The driver of that car entered the house, exited shortly thereafter carrying a small paper sack, and drove away.  A check of Del Castillo’s probation records led the officers to respondent Alberto Leon, whose telephone number Del Castillo had listed as his employer’s.  Leon had been arrested in 1980 on drug charges, and a companion had informed the police at that time that Leon was heavily involved in the importation of drugs into this country.  Before the current investigation began, the Burbank officers had learned that an informant had told a Glendale police officer that Leon stored a large quantity of methaqualone at his residence in Glendale.  During the course of this investigation, the Burbank officers learned that Leon was living at 716 South Sunset Canyon in Burbank.

Subsequently, the officers observed several persons, at least one of whom had prior drug involvement, arriving at the Price Drive residence and leaving with small packages; observed a variety of other material activity at the two residences as well as at a condominium at 7902 Via Magdalena; and witnessed a variety of relevant activity involving respondents’ automobiles.  The officers also observed respondents Sanchez and Stewart board separate flights for Miami.  The pair later returned to Los Angeles together, consented to a search of their luggage that revealed only a small amount of marihuana, and left the airport.  Based on these and other observations summarized in the affidavit, Officer Cyril Rombach of the Burbank Police Department, an experienced and well-trained narcotics investigator, prepared an application for a warrant to search 620 Price Drive, 716 South Sunset Canyon, 7902 Via Magdalena, and automobiles registered to each of the respondents for an extensive list of items believed to be related to respondents’ drug trafficking activities.  Officer Rombach’s extensive application was reviewed by several Deputy District Attorneys.

A facially valid search warrant was issued in September, 1981, by a State Superior Court Judge.  The ensuing searches produced large quantities of drugs at the Via Magdalena and Sunset Canyon addresses and a small quantity at the Price Drive residence.  Other evidence was discovered at each of the residences and in Stewart’s and Del Castillo’s automobiles.  Respondents were indicted by a grand jury in the District Court for the Central District of California and charged with conspiracy to possess and distribute cocaine and a variety of substantive counts.

The respondents then filed motions to suppress the evidence seized pursuant to the warrant.  The District Court held an evidentiary hearing and, while recognizing that the case was a close one, granted the motions to suppress in part.  It concluded that the affidavit was insufficient to establish probable cause, but did not suppress all of the evidence as to all of the respondents because none of the respondents had standing to challenge all of the searches.  In response to a request from the Government, the court made clear that Officer Rombach had acted in good faith, but it rejected the Government’s suggestion that the Fourth Amendment exclusionary rule should not apply where evidence is seized in reasonable, good faith reliance on a search warrant.

The District Court denied the Government’s motion for reconsideration, and a divided panel of the Court of Appeals for the Ninth Circuit affirmed.  The Court of Appeals first concluded that Officer Rombach’s affidavit could not establish probable cause to search the Price Drive residence.  To the extent that the affidavit set forth facts demonstrating the basis of the informant’s knowledge of criminal activity, the information included was fatally stale.  The affidavit, moreover, failed to establish the informant’s credibility.  Accordingly, the Court of Appeals concluded that the information provided by the informant was inadequate under both prongs of the two-part test established in Aguilar v. Texas and Spinelli v. United States.

The officers’ independent investigation neither cured the staleness nor corroborated the details of the informant’s declarations.  The Court of Appeals then considered whether the affidavit formed a proper basis for the search of the Sunset Canyon residence.  In its view, the affidavit included no facts indicating the basis for the informants’ statements concerning respondent Leon’s criminal activities, and was devoid of information establishing the informants’ reliability.  Because these deficiencies had not been cured by the police investigation, the District Court properly suppressed the fruits of the search.  The Court of Appeals refused the Government’s invitation to recognize a good faith exception to the Fourth Amendment exclusionary rule.

The Government’s petition for certiorari expressly declined to seek review of the lower courts’ determinations that the search warrant was unsupported by probable cause, and presented only the question “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.”

We granted certiorari to consider the propriety of such a modification.  Although it undoubtedly is within our power to consider the question whether probable cause existed under the “totality of the circumstances” test announced last Term in Illinois v. Gates (1983), that question has not been briefed or argued; and it is also within our authority, which we choose to exercise, to take the case as it comes to us, accepting the Court of Appeals’ conclusion that probable cause was lacking under the prevailing legal standards.

We have concluded that, in the Fourth Amendment context, the exclusionary rule can be modified somewhat without jeopardizing its ability to perform its intended functions.  Accordingly, we reverse the judgment of the Court of Appeals.


Language in opinions of this Court and of individual Justices has sometimes implied that the exclusionary rule is a necessary corollary of the Fourth Amendment, or that the rule is required by the conjunction of the Fourth and Fifth Amendments.  These implications need not detain us long.  The Fifth Amendment theory has not withstood critical analysis or the test of time, and the Fourth Amendment “has never been interpreted to proscribe the introduction of illegally seized evidence in all proceedings or against all persons.”  

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.” The wrong condemned by the Amendment is “fully accomplished” by the unlawful search or seizure itself, and the exclusionary rule is neither intended nor able to “cure the invasion of the defendant’s rights which he has already suffered.”  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.”

Whether the exclusionary sanction is appropriately imposed in a particular case, our decisions make clear, is “an issue separate from the question whether the Fourth Amendment rights of the party seeking to invoke the rule were violated by police conduct.”

Only the former question is currently before us, and it must be resolved by weighing the costs and benefits of preventing the use in the prosecution’s case in chief of inherently trustworthy tangible evidence obtained in reliance on a search warrant issued by a detached and neutral magistrate that ultimately is found to be defective.

The substantial social costs exacted by the exclusionary rule for the vindication of Fourth Amendment rights have long been a source of concern.  “Our cases have consistently recognized that unbending application of the exclusionary sanction to enforce ideals of governmental rectitude would impede unacceptably the truthfinding functions of judge and jury.”

An objectionable collateral consequence of this interference with the criminal justice system’s truthfinding function is that some guilty defendants may go free or receive reduced sentences as a result of favorable plea bargains.  Particularly when law enforcement officers have acted in objective good faith or their transgressions have been minor, the magnitude of the benefit conferred on such guilty defendants offends basic concepts of the criminal justice system.  Indiscriminate application of the exclusionary rule, therefore, may well “generate disrespect for the law and administration of justice.”

Accordingly, “[a]s with any remedial device, the application of the rule has been restricted to those areas where its remedial objectives are thought most efficaciously served.”

Close attention to those remedial objectives has characterized our recent decisions concerning the scope of the Fourth Amendment exclusionary rule. The Court has, to be sure, not seriously questioned, “in the absence of a more efficacious sanction, the continued application of the rule to suppress evidence from the [prosecution’s] case where a Fourth Amendment violation has been substantial and deliberate….”

Nevertheless, the balancing approach that has evolved in various contexts—including criminal trials—”forcefully suggest[s] that the exclusionary rule be more generally modified to permit the introduction of evidence obtained in the reasonable good faith belief that a search or seizure was in accord with the Fourth Amendment.”

In Stone v. Powell, the Court emphasized the costs of the exclusionary rule, expressed its view that limiting the circumstances under which Fourth Amendment claims could be raised in federal habeas corpus proceedings would not reduce the rule’s deterrent effect, and held that a state prisoner who has been afforded a full and fair opportunity to litigate a Fourth Amendment claim may not obtain federal habeas relief on the ground that unlawfully obtained evidence had been introduced at his trial.

Proposed extensions of the exclusionary rule to proceedings other than the criminal trial itself have been evaluated and rejected under the same analytic approach.  In United States v. Calandra, for example, we declined to allow grand jury witnesses to refuse to answer questions based on evidence obtained from an unlawful search or seizure, since “any incremental deterrent effect which might be achieved by extending the rule to grand jury proceedings is uncertain, at best.”

Similarly, in United States v. Janis, we permitted the use in federal civil proceedings of evidence illegally seized by state officials, since the likelihood of deterring police misconduct through such an extension of the exclusionary rule was insufficient to outweigh its substantial social costs.  In so doing, we declared that, “if . . . the exclusionary rule does not result in appreciable deterrence, then, clearly, its use in the instant situation is unwarranted.”

As cases considering the use of unlawfully obtained evidence in criminal trials themselves make clear, it does not follow from the emphasis on the exclusionary rule’s deterrent value that “anything which deters illegal searches is thereby commanded by the Fourth Amendment.”  In determining whether persons aggrieved solely by the introduction of damaging evidence unlawfully obtained from their coconspirators or codefendants could seek suppression, for example, we found that the additional benefits of such an extension of the exclusionary rule would not outweigh its costs.

Standing to invoke the rule has thus been limited to cases in which the prosecution seeks to use the fruits of an illegal search or seizure against the victim of police misconduct.  Even defendants with standing to challenge the introduction in their criminal trials of unlawfully obtained evidence cannot prevent every conceivable use of such evidence.  Evidence obtained in violation of the Fourth Amendment and inadmissible in the prosecution’s case in chief may be used to impeach a defendant’s direct testimony. A similar assessment of the “incremental furthering” of the ends of the exclusionary rule led us to conclude in United States v. Havens that evidence inadmissible in the prosecution’s case in chief or otherwise as substantive evidence of guilt may be used to impeach statements made by a defendant in response to “proper cross-examination reasonably suggested by the defendant’s direct examination.”

When considering the use of evidence obtained in violation of the Fourth Amendment in the prosecution’s case in chief, moreover, we have declined to adopt a per se or “but for” rule that would render inadmissible any evidence that came to light through a chain of causation that began with an illegal arrest.  We also have held that a witness’ testimony may be admitted even when his identity was discovered in an unconstitutional search.  The perception underlying these decisions—that the connection between police misconduct and evidence of crime may be sufficiently attenuated to permit the use of that evidence at trial—is a product of considerations relating to the exclusionary rule and the constitutional principles it is designed to protect.  In short, the “dissipation of the taint” concept that the Court has applied in deciding whether exclusion is appropriate in a particular case “attempts to mark the point at which the detrimental consequences of illegal police action become so attenuated that the deterrent effect of the exclusionary rule no longer justifies its cost.”

Not surprisingly in view of this purpose, an assessment of the flagrancy of the police misconduct constitutes an important step in the calculus.  The same attention to the purposes underlying the exclusionary rule also has characterized decisions not involving the scope of the rule itself.  We have not required suppression of the fruits of a search incident to an arrest made in good faith reliance on a substantive criminal statute that subsequently is declared unconstitutional.  Similarly, although the Court has been unwilling to conclude that new Fourth Amendment principles are always to have only prospective effect, no Fourth Amendment decision marking a “clear break with the past” has been applied retroactively.

The propriety of retroactive application of a newly announced Fourth Amendment principle, moreover, has been assessed largely in terms of the contribution retroactivity might make to the deterrence of police misconduct.

As yet, we have not recognized any form of good faith exception to the Fourth Amendment exclusionary rule.  But the balancing approach that has evolved during the years of experience with the rule provides strong support for the modification currently urged upon us.  As we discuss below, our evaluation of the costs and benefits of suppressing reliable physical evidence seized by officers reasonably relying on a warrant issued by a detached and neutral magistrate leads to the conclusion that such evidence should be admissible in the prosecution’s case in chief.


Because a search warrant “provides the detached scrutiny of a neutral magistrate, which is a more reliable safeguard against improper searches than the hurried judgment of a law enforcement officer ‘engaged in the often competitive enterprise of ferreting out crime,'” we have expressed a strong preference for warrants, and declared that, “in a doubtful or marginal case, a search under a warrant may be sustainable where without one it would fall.”

Reasonable minds frequently may differ on the question whether a particular affidavit establishes probable cause, and we have thus concluded that the preference for warrants is most appropriately effectuated by according “great deference” to a magistrate’s determination.  Deference to the magistrate, however, is not boundless.  It is clear, first, that the deference accorded to a magistrate’s finding of probable cause does not preclude inquiry into the knowing or reckless falsity of the affidavit on which that determination was based.

Second, the courts must also insist that the magistrate purport to “perform his neutral and detached’ function and not serve merely as a rubber stamp for the police.”  A magistrate failing to “manifest that neutrality and detachment demanded of a judicial officer when presented with a warrant application” and who acts instead as “an adjunct law enforcement officer” cannot provide valid authorization for an otherwise unconstitutional search.

Third, 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.”  “Sufficient information must be presented to the magistrate to allow that official to determine probable cause; his action cannot be a mere ratification of the bare conclusions of others.”

Even if the warrant application was supported by more than a “bare bones” affidavit, a reviewing court may properly conclude that, notwithstanding the deference that magistrates deserve, the warrant was invalid because the magistrate’s probable cause determination reflected an improper analysis of the totality of the circumstances, or because the form of the warrant was improper in some respect.

Only in the first of these three situations, however, has the Court set forth a rationale for suppressing evidence obtained pursuant to a search warrant; in the other areas, it has simply excluded such evidence without considering whether Fourth Amendment interests will be advanced.  To the extent that proponents of exclusion rely on its behavioral effects on judges and magistrates in these areas, their reliance is misplaced.  First, the exclusionary rule is designed to deter police misconduct, rather than to punish the errors of judges and magistrates.  Second, there exists no evidence suggesting that judges and magistrates are inclined to ignore or subvert the Fourth Amendment, or that lawlessness among these actors requires application of the extreme sanction of exclusion.

Third, and most important, we discern no basis, and are offered none, for believing that exclusion of evidence seized pursuant to a warrant will have a significant deterrent effect on the issuing judge or magistrate.  Many of the factors that indicate that the exclusionary rule cannot provide an effective “special” or “general” deterrent for individual offending law enforcement officers apply as well to judges or magistrates.  And, to the extent that the rule is thought to operate as a “systemic” deterrent on a wider audience, it clearly can have no such effect on individuals empowered to issue search warrants.  Judges and magistrates are not adjuncts to the law enforcement team; as neutral judicial officers, they have no stake in the outcome of particular criminal prosecutions.  The threat of exclusion thus cannot be expected significantly to deter them.  Imposition of the exclusionary sanction is not necessary meaningfully to inform judicial officers of their errors, and we cannot conclude that admitting evidence obtained pursuant to a warrant while at the same time declaring that the warrant was somehow defective will in any way reduce judicial officers’ professional incentives to comply with the Fourth Amendment, encourage them to repeat their mistakes, or lead to the granting of all colorable warrant requests. 


If exclusion of evidence obtained pursuant to a subsequently invalidated warrant is to have any deterrent effect, therefore, it must alter the behavior of individual law enforcement officers or the policies of their departments.  One could argue that applying the exclusionary rule in cases where the police failed to demonstrate probable cause in the warrant application deters future inadequate presentations or “magistrate shopping,” and thus promotes the ends of the Fourth Amendment.  Suppressing evidence obtained pursuant to a technically defective warrant supported by probable cause also might encourage officers to scrutinize more closely the form of the warrant, and to point out suspected judicial errors.  We find such arguments speculative, and conclude that suppression of evidence obtained pursuant to a warrant should be ordered only on a case-by-case basis, and only in those unusual cases in which exclusion will further the purposes of the exclusionary rule.

We have frequently questioned whether the exclusionary rule can have any deterrent effect when the offending officers acted in the objectively reasonable belief that their conduct did not violate the Fourth Amendment.  “No empirical researcher, proponent or opponent of the rule has yet been able to establish with any assurance whether the rule has a deterrent effect. . . .”

But even assuming that the rule effectively deters some police misconduct and provides incentives for the law enforcement profession as a whole to conduct itself in accord with the Fourth Amendment, it cannot be expected, and should not be applied, to deter objectively reasonable law enforcement activity.

As we observed in Michigan v. Tucker and reiterated in United States v. Peltier:

“The deterrent purpose of the exclusionary rule necessarily assumes that the police have engaged in willful, or at the very least negligent, conduct which has deprived the defendant of some right.  By refusing to admit evidence gained as a result of such conduct, the courts hope to instill in those particular investigating officers, or in their future counterparts, a greater degree of care toward the rights of an accused.  Where the official action was pursued in complete good faith, however, the deterrence rationale loses much of its force.”

The Peltier Court continued:

“If the purpose of the exclusionary rule is to deter unlawful police conduct, then evidence obtained from a search should be suppressed only if it can be said that the law enforcement officer had knowledge, or may properly be charged with knowledge, that the search was unconstitutional under the Fourth Amendment.”

In short, where the officer’s conduct is objectively reasonable, “excluding the evidence will not further the ends of the exclusionary rule in any appreciable way; for it is painfully apparent that . . . the officer is acting as a reasonable officer would and should act in similar circumstances. Excluding the evidence can in no way affect his future conduct unless it is to make him less willing to do his duty.”

This is particularly true, we believe, when an officer, acting with objective good faith, has obtained a search warrant from a judge or magistrate and acted within its scope.  In most such cases, there is no police illegality, and thus nothing to deter.  It is the magistrate’s responsibility to determine whether the officer’s allegations establish probable cause and, if so, to issue a warrant comporting in form with the requirements of the Fourth Amendment.  In the ordinary case, an officer cannot be expected to question the magistrate’s probable cause determination or his judgment that the form of the warrant is technically sufficient.  “Once the warrant issues, there is literally nothing more the policeman can do in seeking to comply with the law.”  Penalizing the officer for the magistrate’s error, rather than his own, cannot logically contribute to the deterrence of Fourth Amendment violations. 


We conclude that the marginal or nonexistent benefits produced by suppressing evidence obtained in objectively reasonable reliance on a subsequently invalidated search warrant cannot justify the substantial costs of exclusion.  We do not suggest, however, that exclusion is always inappropriate in cases where an officer has obtained a warrant and abided by its terms.  “Searches pursuant to a warrant will rarely require any deep inquiry into reasonableness,” for “a warrant issued by a magistrate normally suffices to establish” that a law enforcement officer has “acted in good faith in conducting the search.”  Nevertheless, the officer’s reliance on the magistrate’s probable cause determination and on the technical sufficiency of the warrant he issues must be objectively reasonable, and it is clear that, in some circumstances the officer will have no reasonable grounds for believing that the warrant was properly issued.

Suppression therefore remains an appropriate remedy if the magistrate or judge in issuing a warrant was misled by information in an affidavit that the affiant knew was false or would have known was false except for his reckless disregard of the truth.  The exception we recognize today will also not apply in cases where the issuing magistrate wholly abandoned his judicial role in the manner condemned in Lo-Ji Sales, Inc. v. New York (1979); in such circumstances, no reasonably well-trained officer should rely on the warrant.  Nor would an officer manifest objective good faith in relying on a warrant based on an affidavit “so lacking in indicia of probable cause as to render official belief in its existence entirely unreasonable.”

Finally, depending on the circumstances of the particular case, a warrant may be so facially deficient—i.e., in failing to particularize the place to be searched or the things to be seized—that the executing officers cannot reasonably presume it to be valid.  In so limiting the suppression remedy, we leave untouched the probable cause standard and the various requirements for a valid warrant.  Other objections to the modification of the Fourth Amendment exclusionary rule we consider to be insubstantial.

The good faith exception for searches conducted pursuant to warrants is not intended to signal our unwillingness strictly to enforce the requirements of the Fourth Amendment, and we do not believe that it will have this effect.  As we have already suggested, the good faith exception, turning as it does on objective reasonableness, should not be difficult to apply in practice.  When officers have acted pursuant to a warrant, the prosecution should ordinarily be able to establish objective good faith without a substantial expenditure of judicial time.

Nor are we persuaded that application of a good faith exception to searches conducted pursuant to warrants will preclude review of the constitutionality of the search or seizure, deny needed guidance from the courts, or freeze Fourth Amendment law in its present state.  There is no need for courts to adopt the inflexible practice of always deciding whether the officers’ conduct manifested objective good faith before turning to the question whether the Fourth Amendment has been violated.  Defendants seeking suppression of the fruits of allegedly unconstitutional searches or seizures undoubtedly raise live controversies which Art. III empowers federal courts to adjudicate.  …

If the resolution of a particular Fourth Amendment question is necessary to guide future action by law enforcement officers and magistrates, nothing will prevent reviewing courts from deciding that question before turning to the good faith issue.  Indeed, it frequently will be difficult to determine whether the officers acted reasonably without resolving the Fourth Amendment issue.  Even if the Fourth Amendment question is not one of broad import, reviewing courts could decide in particular cases that magistrates under their supervision need to be informed of their errors, and so evaluate the officers’ good faith only after finding a violation.  In other circumstances, those courts could reject suppression motions posing no important Fourth Amendment questions by turning immediately to a consideration of the officers’ good faith.  We have no reason to believe that our Fourth Amendment jurisprudence would suffer by allowing reviewing courts to exercise an informed discretion in making this choice.


When the principles we have enunciated today are applied to the facts of this case, it is apparent that the judgment of the Court of Appeals cannot stand.  The Court of Appeals applied the prevailing legal standards to Officer Rombach’s warrant application, and concluded that the application could not support the magistrate’s probable cause determination.  In so doing, the court clearly informed the magistrate that he had erred in issuing the challenged warrant.  This aspect of the court’s judgment is not under attack in this proceeding.

Having determined that the warrant should not have issued, the Court of Appeals understandably declined to adopt a modification of the Fourth Amendment exclusionary rule that this Court had not previously sanctioned.  Although the modification finds strong support in our previous cases, the Court of Appeals’ commendable self-restraint is not to be criticized.  We have now reexamined the purposes of the exclusionary rule and the propriety of its application in cases where officers have relied on a subsequently invalidated search warrant.  Our conclusion is that the rule’s purposes will only rarely be served by applying it in such circumstances.

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.  Only respondent Leon has contended that no reasonably well trained police officer could have believed that there existed probable cause to search his house; significantly, the other respondents advance no comparable argument. Officer Rombach’s application for a warrant clearly was supported by much more than a “bare bones” affidavit.  The affidavit related the results of an extensive investigation and, as the opinions of the divided panel of the Court of Appeals make clear, provided evidence sufficient to create disagreement among thoughtful and competent judges as to the existence of probable cause.  Under these circumstances, the officers’ reliance on the magistrate’s determination of probable cause was objectively reasonable, and application of the extreme sanction of exclusion is inappropriate.

Accordingly, the judgment of the Court of Appeals is 


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