SUPREME COURT OF THE UNITED STATES
543 U.S. 405; 125 S.Ct. 834; 160 L.Ed.2d 842

ILLINOIS, PETITIONER v. ROY I. CABALLES

No. 03-923

November 10, 2004, Argued

January 24, 2005, Decided

NOTICE: [*1] This preliminary LEXIS version is unedited and subject to revision.

The LEXIS pagination of this document is subject to change pending release of the final published version.

PRIOR HISTORY: ON WRIT OF CERTIORARI TO THE SUPREME COURT OF ILLINOIS.

DISPOSITION: 207 Ill. 2d 504, 802 N. E. 2d 202, vacated and remanded.

SYLLABUS:

After an Illinois state trooper stopped respondent for speeding and radioed in, a second trooper, overhearing the transmission, drove to the scene with his narcotics-detection dog and walked the dog around respondent's car while the first trooper wrote respondent a warning ticket. When the dog alerted at respondent's trunk, the officers searched the trunk, found marijuana, and arrested respondent. At respondent's drug trial, the court denied his motion to suppress the seized evidence, holding, inter alia, that the dog's alerting provided sufficient probable cause to conduct the search. Respondent was [*2] convicted, but the Illinois Supreme Court reversed, finding that because there were no specific and articulable facts to suggest drug activity, use of the dog unjustifiably enlarged a routine traffic stop into a drug investigation.

Held: 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. Pp. 2-4.

207 Ill. 2d 504, 802 N. E. 2d 202, vacated and remanded.

JUDGES: STEVENS, J., delivered the opinion of the Court, in which O'CONNOR, SCALIA, KENNEDY, THOMAS, and BREYER, JJ., joined. SOUTER, J., filed a dissenting opinion. GINSBURG, J., filed a dissenting opinion, in which SOUTER, J., joined. REHNQUIST, C. J., took no part in the decision of the case.

OPINION: JUSTICE STEVENS delivered the opinion of the Court.

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 [*3] 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 enlarged the scope of a routine traffic stop into a drug investigation." 207 Ill. 2d 504, 510, 802 N.E.2d 202, 205 (2003).

The question [*4] on which we granted certiorari, 541 U.S. 972 (2004), 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." Pet. for Cert. i. 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. United States v. Jacobsen, 466 U.S. 109, 124 (1984). 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 [*5] 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. People v. Cox, 202 Ill. 2d 462, 782 N.E.2d 275 (2002). 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 [*6] 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. Jacobsen, 466 U.S., at 123. 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." Ibid. 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. [*7] " Id., at 122 (punctuation omitted). In United States v. Place, 462 U.S. 696 (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." Id., at 707; see also Indianapolis v. Edmond, 531 U.S. 32, 40 (2000). Respondent likewise concedes that "drug sniffs are designed, and if properly conducted are generally likely, to reveal only the presence of contraband." Brief for Respondent 17. 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 [*8] expose noncontraband items that otherwise would remain hidden from public view," Place, 462 U.S., at 707 -- 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, 533 U.S. 27 (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." Id., at 38. 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 [*9] 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.

THE CHIEF JUSTICE took no part in the decision of this case.

DISSENTBY: SOUTER; GINSBURG

DISSENT: JUSTICE SOUTER, dissenting.

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.

In United States v. Place, 462 U.S. 696 (1983), we categorized the sniff of the narcotics-seeking dog as "sui generis" under the Fourth Amendment and held it was not a search. Id., at 707. The classification rests not only upon the limited nature of the intrusion, but on a further premise that experience has shown to be untenable, the assumption [*10] that trained sniffing dogs do not err. What we have learned about the fallibility of dogs in the years since Place was decided would itself be reason to call for reconsidering Place's decision against treating the intentional use of a trained dog as a search. The portent of this very case, however, adds insistence to the call, for an uncritical adherence to Place would render the Fourth Amendment indifferent to suspicionless and indiscriminate sweeps of cars in parking garages and pedestrians on sidewalks; if a sniff is not preceded by a seizure subject to Fourth Amendment notice, it escapes Fourth Amendment review entirely unless it is treated as a search. We should not wait for these developments to occur before rethinking Place's analysis, which invites such untoward consequences. n1

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n1 I also join JUSTICE GINSBURG's dissent, post, p. ___. Without directly reexamining the soundness of the Court's analysis of government dog sniffs in Place, she demonstrates that investigation into a matter beyond the subject of the traffic stop here offends the rule in Terry v. Ohio, 392 U.S. 1 (1968), the analysis I, too, adopt.


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At the heart both of Place 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. n2 See ibid. ("The sniff discloses only the presence or absence of narcotics, a contraband item"); ante, at 3-4 (assuming "that a canine sniff by a well-trained narcotics dog will only reveal 'the presence or absence of narcotics, a contraband item'" (quoting Place, supra, at 707)). 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. Ante, at 4.

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n2 Another proffered justification for sui generis status is that a dog sniff is a particularly nonintrusive procedure. United States v. Place, 462 U.S. 696, 707 (1983). I agree with JUSTICE GINSBURG that the introduction of a dog to a traffic stop (let alone an encounter with someone walking down the street) can in fact be quite intrusive. Post, at 4-5 (dissenting opinion).


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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. See, e.g., United States v. Kennedy, 131 F.3d 1371, 1378 (CA10 1997) (describing a dog that had a 71% accuracy rate); United States v. Scarborough, 128 F.3d 1373, 1378, n. 3 (CA10 1997) (describing a dog that erroneously alerted 4 times out of 19 while working for the postal service and 8% of the time over its entire career); United States v. Limares, 269 F.3d 794, 797 (CA7 2001) (accepting as reliable a dog that gave false positives between 7 and 38% of the time); Laime v. State, 347 Ark. 142, 159, 60 S. W. 3d 464, 476 (2001) (speaking of a dog that made between 10 and 50 errors); United States v. $ 242,484.00, 351 F.3d 499, 511 (CA11 2003) [*13] (noting that because as much as 80% of all currency in circulation contains drug residue, a dog alert "is of little value"), vacated on other grounds by rehearing en banc, 357 F.3d 1225 (CA11 2004); United States v. Carr, 25 F.3d 1194, 1214-1217 (CA3 1994) (Becker, J., concurring in part and dissenting in part) ("[A] substantial portion of United States currency . . . is tainted with sufficient traces of controlled substances to cause a trained canine to alert to their presence"). Indeed, a study cited by Illinois in this case for the proposition that dog sniffs are "generally reliable" shows that dogs in artificial testing situations return false positives anywhere from 12.5 to 60% of the time, depending on the length of the search. See Reply Brief for Petitioner 13; K. Garner et al., Duty Cycle of the Detector Dog: A Baseline Study 12 (Apr. 2001) (prepared under Federal Aviation Administration grant by the Institute for Biological Detection Systems of Auburn University). In practical terms, the evidence is clear that the dog that alerts hundreds of times will be wrong dozens of times.

Once the dog's fallibility is recognized, however, that ends [*14] the justification claimed in Place for treating the sniff as sui generis under 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 reas