Illinois v. Caballes

543 U.S. 405

Case Year: 2005

Case Ruling: 6-3, Vacated and Remanded

Opinion Justice: Stevens

More Information

Concurring Opinions

Dissenting Opinions

Court Opinion Joiner(s):

Breyer, Kennedy, O'Connor, Scalia, Thomas


1st Concurring Opinion



1st Dissenting Opinion

Author: Souter


2nd Concurring Opinion



2nd Dissenting Opinion

Author: Ginsburg

Joiner(s): Souter

3rd Concurring Opinion



3rd Dissenting Opinion



Other Concurring Opinions:


[Justice Stevens's opinion contains the statement of the facts.]



Illinois State Trooper Daniel Gillette stopped respondent for speeding on an interstate highway. When Gillette radioed the police dispatcher to report the stop, a second trooper, Craig Graham, a member of the Illinois State Police Drug Interdiction Team, overheard the transmission and immediately headed for the scene with his narcotics-detection dog. When they arrived, respondent's car was on the shoulder of the road and respondent was in Gillette's vehicle. While Gillette was in the process of writing a warning ticket, Graham walked his dog around respondent's car. The dog alerted at the trunk. Based on that alert, the officers searched the trunk, found marijuana, and arrested respondent. The entire incident lasted less than 10 minutes.

Respondent was convicted of a narcotics offense and sentenced to 12 years' imprisonment and a $256,136 fine. The trial judge denied his motion to suppress the seized evidence and to quash his arrest. He held that the officers had not unnecessarily prolonged the stop and that the dog alert was sufficiently reliable to provide probable cause to conduct the search. Although the Appellate Court affirmed, the Illinois Supreme Court reversed, concluding that because the canine sniff was performed without any "'specific and articulable facts'" to suggest drug activity, the use of the dog "unjustifiably enlarg[ed] the scope of a routine traffic stop into a drug investigation."

The question on which we granted certiorari is narrow: "Whether the Fourth Amendment requires reasonable, articulable suspicion to justify using a drug-detection dog to sniff a vehicle during a legitimate traffic stop." Thus, we proceed on the assumption that the officer conducting the dog sniff had no information about respondent except that he had been stopped for speeding; accordingly, we have omitted any reference to facts about respondent that might have triggered a modicum of suspicion.

Here, the initial seizure of respondent when he was stopped on the highway was based on probable cause, and was concededly lawful. It is nevertheless clear that a seizure that is lawful at its inception can violate the Fourth Amendment if its manner of execution unreasonably infringes interests protected by the Constitution. A seizure that is justified solely by the interest in issuing a warning ticket to the driver can become unlawful if it is prolonged beyond the time reasonably required to complete that mission. In an earlier case involving a dog sniff that occurred during an unreasonably prolonged traffic stop, the Illinois Supreme Court held that use of the dog and the subsequent discovery of contraband were the product of an unconstitutional seizure. We may assume that a similar result would be warranted in this case if the dog sniff had been conducted while respondent was being unlawfully detained.

In the state-court proceedings, however, the judges carefully reviewed the details of Officer Gillette's conversations with respondent and the precise timing of his radio transmissions to the dispatcher to determine whether he had improperly extended the duration of the stop to enable the dog sniff to occur. We have not recounted those details because we accept the state court's conclusion that the duration of the stop in this case was entirely justified by the traffic offense and the ordinary inquiries incident to such a stop.

Despite this conclusion, the Illinois Supreme Court held that the initially lawful traffic stop became an unlawful seizure solely as a result of the canine sniff that occurred outside respondent's stopped car. That is, the court characterized the dog sniff as the cause rather than the consequence of a constitutional violation. In its view, the use of the dog converted the citizen-police encounter from a lawful traffic stop into a drug investigation, and because the shift in purpose was not supported by any reasonable suspicion that respondent possessed narcotics, it was unlawful. In our view, conducting a dog sniff would not change the character of a traffic stop that is lawful at its inception and otherwise executed in a reasonable manner, unless the dog sniff itself infringed respondent's constitutionally protected interest in privacy. Our cases hold that it did not.

Official conduct that does not "compromise any legitimate interest in privacy" is not a search subject to the Fourth Amendment. We have held that any interest in possessing contraband cannot be deemed "legitimate," and thus, governmental conduct that only reveals the possession of contraband "compromises no legitimate privacy interest." This is because the expectation "that certain facts will not come to the attention of the authorities" is not the same as an interest in "privacy that society is prepared to consider reasonable." In United States v. Place, (1983), we treated a canine sniff by a well-trained narcotics-detection dog as " sui generis" because it "discloses only the presence or absence of narcotics, a contraband item." Respondent likewise concedes that "drug sniffs are designed, and if properly conducted are generally likely, to reveal only the presence of contraband." Although respondent argues that the error rates, particularly the existence of false positives, call into question the premise that drug-detection dogs alert only to contraband, the record contains no evidence or findings that support his argument. Moreover, respondent does not suggest that an erroneous alert, in and of itself, reveals any legitimate private information, and, in this case, the trial judge found that the dog sniff was sufficiently reliable to establish probable cause to conduct a full-blown search of the trunk.

Accordingly, the use of a well-trained narcotics-detection dog--one that "does not expose noncontraband items that otherwise would remain hidden from public view" during a lawful traffic stop, generally does not implicate legitimate privacy interests. In this case, the dog sniff was performed on the exterior of respondent's car while he was lawfully seized for a traffic violation. Any intrusion on respondent's privacy expectations does not rise to the level of a constitutionally cognizable infringement.

This conclusion is entirely consistent with our recent decision that the use of a thermal-imaging device to detect the growth of marijuana in a home constituted an unlawful search. Kyllo v. United States (2001). Critical to that decision was the fact that the device was capable of detecting lawful activity--in that case, intimate details in a home, such as "at what hour each night the lady of the house takes her daily sauna and bath." The legitimate expectation that information about perfectly lawful activity will remain private is categorically distinguishable from respondent's hopes or expectations concerning the nondetection of contraband in the trunk of his car. A dog sniff conducted during a concededly lawful traffic stop that reveals no information other than the location of a substance that no individual has any right to possess does not violate the Fourth Amendment.

The judgment of the Illinois Supreme Court is vacated, and the case is remanded for further proceedings not inconsistent with this opinion.

It is so ordered.


I would hold that using the dog for the purposes of determining the presence of marijuana in the car's trunk was a search unauthorized as an incident of the speeding stop and unjustified on any other ground. I would accordingly affirm the judgment of the Supreme Court of Illinois, and I respectfully dissent....

At the heart both of [ United States v. ] Place (1983), and the Court's opinion today is the proposition that sniffs by a trained dog are sui generis because a reaction by the dog in going alert is a response to nothing but the presence of contraband. Hence, the argument goes, because the sniff can only reveal the presence of items devoid of any legal use, the sniff "does not implicate legitimate privacy interests" and is not to be treated as a search.

The infallible dog, however, is a creature of legal fiction. Although the Supreme Court of Illinois did not get into the sniffing averages of drug dogs, their supposed infallibility is belied by judicial opinions describing well-trained animals sniffing and alerting with less than perfect accuracy, whether owing to errors by their handlers, the limitations of the dogs themselves, or even the pervasive contamination of currency by cocaine.

Once the dog's fallibility is recognized ... that ends the justification claimed in Place for treating the sniff as sui generisunder the Fourth Amendment: the sniff alert does not necessarily signal hidden contraband, and opening the container or enclosed space whose emanations the dog has sensed will not necessarily reveal contraband or any other evidence of crime. This is not, of course, to deny that a dog's reaction may provide reasonable suspicion, or probable cause, to search the container or enclosure; the Fourth Amendment does not demand certainty of success to justify a search for evidence or contraband. The point is simply that the sniff and alert cannot claim the certainty that Place assumed, both in treating the deliberate use of sniffing dogs as sui generis and then taking that characterization as a reason to say they are not searches subject to Fourth Amendment scrutiny. And when that aura of uniqueness disappears, there is no basis in Place's reasoning, and no good reason otherwise, to ignore the actual function that dog sniffs perform. They are conducted to obtain information about the contents of private spaces beyond anything that human senses could perceive, even when conventionally enhanced. The information is not provided by independent third parties beyond the reach of constitutional limitations, but gathered by the government's own officers in order to justify searches of the traditional sort, which may or may not reveal evidence of crime but will disclose anything meant to be kept private in the area searched. Thus in practice the government's use of a trained narcotics dog functions as a limited search to reveal undisclosed facts about private enclosures, to be used to justify a further and complete search of the enclosed area. And given the fallibility of the dog, the sniff is the first step in a process that may disclose "intimate details" without revealing contraband, just as a thermal-imaging device might do, as described in Kyllo v. United States (2001).

It makes sense, then, to treat a sniff as the search that it amounts to in practice, and to rely on the body of our Fourth Amendment cases, including Kyllo, in deciding whether such a search is reasonable. As a general proposition, using a dog to sniff for drugs is subject to the rule that the object of enforcing criminal laws does not, without more, justify suspicionless Fourth Amendment intrusions. Since the police claim to have had no particular suspicion that Caballes was violating any drug law, this sniff search must stand or fall on its being ancillary to the traffic stop that led up to it. It is true that the police had probable cause to stop the car for an offense committed in the officer's presence, which Caballes concedes could have justified his arrest. There is no occasion to consider authority incident to arrest, however, for the police did nothing more than detain Caballes long enough to check his record and write a ticket. As a consequence, the reasonableness of the search must be assessed in relation to the actual delay the police chose to impose, and the Fourth Amendment consequences of stopping for a traffic citation are settled law.

In Berkemer v. McCarty (1984), we held that the analogue of the common traffic stop was the limited detention for investigation authorized by Terry v. Ohio (1968). While Terry authorized a restricted incidental search for weapons when reasonable suspicion warrants such a safety measure, the Court took care to keep a Terry stop from automatically becoming a foot in the door for all investigatory purposes; the permissible intrusion was bounded by the justification for the detention. Although facts disclosed by enquiry within this limit might give grounds to go further, the government could not otherwise take advantage of a suspect's immobility to search for evidence unrelated to the reason for the detention. That has to be the rule unless Terry is going to become an open-sesame for general searches, and that rule requires holding that the police do not have reasonable grounds to conduct sniff searches for drugs simply because they have stopped someone to receive a ticket for a highway offense. Since the police had no indication of illegal activity beyond the speed of the car in this case, the sniff search should be held unreasonable under the Fourth Amendment and its fruits should be suppressed....


In Terry v. Ohio, the Court upheld the stop and subsequent frisk of an individual based on an officer's observation of suspicious behavior and his reasonable belief that the suspect was armed. In a Terry-type investigatory stop, "the officer's action [must be] justified at its inception, and ... reasonably related in scope to the circumstances which justified the interference in the first place."...

... I would apply Terry's reasonable-relation test, as the Illinois Supreme Court did, to determine whether the canine sniff impermissibly expanded the scope of the initially valid seizure of Caballes.

It is hardly dispositive that the dog sniff in this case may not have lengthened the duration of the stop. Terry, it merits repetition, instructs that any investigation must be "reasonably related in scope to the circumstances which justified the interference in the first place." The unwarranted and nonconsensual expansion of the seizure here from a routine traffic stop to a drug investigation broadened the scope of the investigation in a manner that, in my judgment, runs afoul of the Fourth Amendment.

The Court rejects ... the application of Terry to a traffic stop converted, by calling in a dog, to a drug search. The Court so rules, holding that a dog sniff does not render a seizure that is reasonable in time unreasonable in scope. Dog sniffs that detect only the possession of contraband may be employed without offense to the Fourth Amendment, the Court reasons, because they reveal no lawful activity and hence disturb no legitimate expectation of privacy.

In my view, the Court diminishes the Fourth Amendment's force by abandoning the second Terry inquiry (was the police action "reasonably related in scope to the circumstances [justifying] the [initial] interference"). Injecting such an animal into a routine traffic stop changes the character of the encounter between the police and the motorist. The stop becomes broader, more adversarial, and (in at least some cases) longer. Caballes--who, as far as Troopers Gillette and Graham knew, was guilty solely of driving six miles per hour over the speed limit--was exposed to the embarrassment and intimidation of being investigated, on a public thoroughfare, for drugs. Even if the drug sniff is not characterized as a Fourth Amendment "search," the sniff surely broadened the scope of the traffic-violation-related seizure.

The Court has never removed police action from Fourth Amendment control on the ground that the action is well calculated to apprehend the guilty. Under today's decision, every traffic stop could become an occasion to call in the dogs, to the distress and embarrassment of the law-abiding population....

The dog sniff in this case, it bears emphasis, was for drug detection only. A dog sniff for explosives, involving security interests not presented here, would be an entirely different matter. Detector dogs are ordinarily trained not as all-purpose sniffers, but for discrete purposes. For example, they may be trained for narcotics detection or for explosives detection or for agricultural products detection.

This Court has distinguished between the general interest in crime control and more immediate threats to public safety. InMichigan Dept. of State Police v. Sitz (1990), this Court upheld the use of a sobriety traffic checkpoint. Balancing the State's interest in preventing drunk driving, the extent to which that could be accomplished through the checkpoint program, and the degree of intrusion the stops involved, the Court determined that the State's checkpoint program was consistent with the Fourth Amendment. Ten years after Sitz, in Indianapolis v. Edmond, this Court held that a drug interdiction checkpoint violated the Fourth Amendment. Despite the illegal narcotics traffic that the Nation is struggling to stem, the Court explained, a "general interest in crime control" did not justify the stops. The Court distinguished the sobriety checkpoints in Sitz on the ground that those checkpoints were designed to eliminate an "immediate, vehicle-bound threat to life and limb."

The use of bomb-detection dogs to check vehicles for explosives without doubt has a closer kinship to the sobriety checkpoints in Sitz than to the drug checkpoints in Edmond. Even if the Court were to change course and characterize a dog sniff as an independent Fourth Amendment search, the immediate, present danger of explosives would likely justify a bomb sniff under the special needs doctrine.... For the reasons stated, I would hold that the police violated Caballes' Fourth Amendment rights when, without cause to suspect wrongdoing, they conducted a dog sniff of his vehicle. I would therefore affirm the judgment of the Illinois Supreme Court.