concurring in the result.
In this case, the Court of Appeals assumed both that the officers had the “reasonable suspicion” necessary to justify an “investigative” stop of respondent under Terry v. Ohio, 392 U. S. 1 (1968), and its progeny, and that the principles of Terry apply to seizures of property. See 660 F. 2d 44, 50 (CA2 1981); ante, at 700. The court held simply that “the prolonged seizure of [respondent’s] baggage went far beyond a mere investigative stop and amounted to a violation of his Fourth Amendment rights.” 660 F. 2d, at 50. See also id., *711at 52, 53. I would affirm the Court of Appeals’ judgment on this ground.
Instead of simply affirming on this ground and putting an end to the matter, the Court decides to reach, and purportedly to resolve, the constitutionality of the seizure of respondent’s luggage on less than probable cause and the exposure of that luggage to a narcotics detection dog. See ante, at 706-707. Apparently, the Court finds itself unable to “resist the pull to decide the constitutional issues involved in this case on a broader basis than the record before [it] imperatively requires.” Street v. New York, 394 U. S. 576, 581 (1969). Because the Court reaches issues unnecessary to its judgment and because I cannot subscribe to the Court’s analysis of those issues, I concur only in the result.
I — l
I have had occasion twice m recent months to discuss the limited scope of the exception to the Fourth Amendment’s probable-cause requirement created by Terry and its progeny. See Florida v. Royer, 460 U. S. 491, 509 (1983) (Brennan, J., concurring in result); Kolender v. Lawson, 461 U. S. 352, 362 (1983) (Brennan, J., concurring). Unfortunately, the unwarranted expansion of that exception which the Court endorses today forces me to elaborate on my previously expressed views.
In Terry the Court expressly declined to address “the constitutional propriety of an investigative ‘seizure’ upon less than probable cause for purposes of ‘detention’ and/or interrogation.” 392 U. S., at 19, n. 16.1 The Court was con*712fronted with “the quite narrow question” of “whether it is always unreasonable for a policeman to seize a person and subject him to a limited search for weapons unless there is probable cause for an arrest.” Id., at 15. In addressing this question, the Court noted that it was dealing “with an entire rubric of police conduct — necessarily swift action predicated upon the on-the-spot observations of the officer on the beat— which historically has not been, and as a practical matter could not be, subjected to the warrant procedure.” Id., at 20. As a result, the conduct involved in the case had to be “tested by the Fourth Amendment’s general proscription against unreasonable searches and seizures.” Ibid, (footnote omitted). The Court’s inquiry into the “reasonableness” of the conduct at issue was based on a “ ‘balancing [of] the need to search [or seize] against the invasion which the search [or seizure] entails.’” Id., at 21, quoting Camara v. Municipal Court, 387 U. S. 523, 537 (1967). The Court concluded that the officer’s conduct was reasonable and stated its holding as follows:
“We merely hold today that where a police officer observes unusual conduct which leads him reasonably to conclude in light of his experience that criminal activity may be afoot and that the persons with whom he is dealing may be armed and presently dangerous, where in the course of investigating this behavior he identifies himself as a policeman and makes reasonable inquiries, and where nothing in the initial stages of the encounter serves to dispel his reasonable fear for his own or others’ safety, he is entitled for the protection of himself and others in the area to conduct a carefully limited search of *713the outer clothing of such persons in an attempt to discover weapons which might be used to assault him.” 392 U. S., at 30.
In Adams v. Williams, 407 U. S. 143 (1972), the Court relied on Terry to endorse “brief” investigative stops based on reasonable suspicion. 407 U. S., at 145-146. In this regard, the Court stated that “[a] brief stop of a suspicious individual, in order to determine his identity or to maintain the status quo momentarily while obtaining more information, may be most reasonable in light of the facts known to the officer at the time.” Id., at 146. The weapons search upheld in Adams was very limited and was based on Terry’s safety rationale. 407 U. S., at 146. The Court stated that the purpose of a “limited” weapons search “is not to discover evidence of crime, but to allow the officer to pursue his investigation without fear of violence. ...” Ibid.
In United States v. Brignoni-Ponce, 422 U. S. 873 (1975), the Court relied on Terry and Adams in holding that “when an officer’s observations lead him reasonably to suspect that a particular vehicle may contain aliens who are illegally in the country, he may stop the car briefly and investigate the circumstances that provoke suspicion.” 422 U. S., at 881.2 The Court based this relaxation of the traditional probable-cause requirement on the importance of the governmental interest in stemming the flow of illegal aliens, on the minimal intrusion of a brief stop, and on the absence of practical alternatives for policing the border. Ibid. The Court noted the limited holdings of Terry and Adams and while authorizing the police to “question the driver and passengers about their citizenship and immigration status, and . . . ask them to explain suspicious circumstances,” the Court expressly stated that “any further detention or search must be based on consent or probable cause.” 422 U. S., at 881-882. See also *714Ybarra v. Illinois, 444 U. S. 85, 93 (1979) (“The Terry case created an exception to the requirement of probable cause, an exception whose ‘narrow scope’ this Court ‘has been careful to maintain’” (footnote omitted)); Dunaway v. New York, 442 U. S. 200, 209-212 (1979) (discussing the narrow scope of Terry and its progeny).3
It is clear that Terry, and the cases that followed it, permit only brief investigative stops and extremely limited searches based on reasonable suspicion. They do not provide the police with a commission to employ whatever investigative techniques they deem appropriate. As I stated in Florida v. Royer, “[t]he scope of a Terry-type ‘investigative’ stop and any attendant search must be extremely limited or the Terry exception would ‘swallow the general rule that Fourth Amendment seizures [and searches] are “reasonable” only if based on probable cause.’” 460 U. S., at 510 (concurring in result), quoting Dunaway v. New York, supra, at 213.
II
In some respects the Court’s opinion in this case can be seen as the logical successor of the plurality opinion in Florida v. Royer, supra. The plurality opinion in Royer contained considerable language which was unnecessary to the judgment, id., at 509 (Brennan, J., concurring in result), regarding the permissible scope of Terry investigative stops. See 460 U. S., at 501-507, and n. 10. Even assuming, however, that the Court finds some support in Royer for its discussion of the scope of Terry stops, the Court today goes *715well beyond Royer in endorsing the notion that the principles of Terry permit “warrantless seizures of personal luggage from the custody of the owner on the basis of less than probable cause, for the purpose of pursuing a limited course of investigation, short of opening the luggage, that would quickly confirm or dispel the authorities’ suspicion.” Ante, at 702. See also ante, at 706. In addition to being unnecessary to the Court’s judgment, see supra, at 711, this suggestion finds no support in Terry or its progeny and significantly dilutes the Fourth Amendment’s protections against government interference with personal property. In short, it represents a radical departure from settled Fourth Amendment principles.
As noted supra, at 711-712, Terry and the cases that followed it authorize a brief “investigative” stop of an individual based on reasonable suspicion and a limited search for weapons if the officer reasonably suspects that the individual is armed and presently dangerous. The purpose of this brief stop is “to determine [the individual’s] identity or to maintain the status quo momentarily while obtaining more information. . . .” Adams v. Williams, 407 U. S., at 146. Anything more than a brief stop “must be based on consent or probable cause.” United States v. Brignoni-Ponce, supra, at 882. During the course of this stop, “the suspect must not be moved or asked to move more than a short distance; physical searches are permitted only to the extent necessary to protect the police officers involved during the encounter; and, most importantly, the suspect must be free to leave after a short time and to decline to answer the questions put to him.” Kolender v. Lawson, 461 U. S., at 365 (Brennan, J., concurring). It is true that Terry stops may involve seizures of personal effects incidental to the seizure of the person involved. Obviously, an officer cannot seize a person without also seizing the personal effects that the individual has in his possession at the time. But there is a difference between *716incidental seizures of personal effects and seizures of property independent of the seizure of the person.
The Fourth Amendment protects “effects” as well as people from unreasonable searches and seizures. In this regard, Justice Stevens pointed out in Texas v. Brown, 460 U. S. 730 (1983), that “[t]he [Fourth] Amendment protects two different interests of the citizen — the interest in retaining possession of property and the interest in maintaining personal privacy.” Id., at 747 (opinion concurring in judgment). “A seizure threatens the former, a search the latter.” Ibid. Even if an item is not searched, therefore, its seizure implicates a protected Fourth Amendment interest. For this reason, seizures of property must be based on probable cause. See Colorado v. Bannister, 449 U. S. 1, 3 (1980); Payton v. New York, 445 U. S. 573, 587 (1980); G. M. Leasing Corp. v. United States, 429 U. S. 338, 351 (1977); Chambers v. Maroney, 399 U. S. 42, 51-52 (1970); Warden v. Hayden, 387 U. S. 294, 309-310 (1967). See also Texas v. Brown, supra, at 747-748 (Stevens, J., concurring in judgment). Neither Terry nor its progeny changed this rule.
In this case, the officers’ seizure of respondent and their later independent seizure of his luggage implicated separate Fourth Amendment interests. First, respondent had a protected interest in maintaining his personal security and privacy. Terry allows this interest to be overcome, and authorizes a limited intrusion, if the officers have reason to suspect that criminal activity is afoot. Second, respondent had a protected interest in retaining possession of his personal effects. While Terry may authorize seizures of personal effects incident to a lawful seizure of the person, nothing in the Terry line of cases authorizes the police to seize personal property, such as luggage, independent of the seizure of the person. Such seizures significantly expand the scope of a Terry stop and may not be effected on less than probable *717cause.4 Obviously, they also significantly expand the scope of the intrusion.
The officers did not develop probable cause to arrest respondent during their encounter with him. See 660 F. 2d, at 50. Therefore, they had to let him go. But despite the absence of probable cause to arrest respondent, the officers seized his luggage and deprived him of possession. Respondent, therefore, was subjected not only to an invasion of his personal security and privacy, but also to an independent dispossession of his personal effects based simply on reasonable suspicion. It is difficult to understand how this intrusion is not more severe than a brief stop for questioning or even a limited, on-the-spot patdown search for weapons.
In my view, as soon as the officers seized respondent’s luggage, independent of their seizure of him, they exceeded the scope of a permissible Terry stop and violated respondent’s Fourth Amendment rights. In addition, the officers’ seizure of respondent’s luggage violated the established rule that seizures of personal effects must be based on probable cause. Their actions, therefore, should not be upheld.
The Court acknowledges that seizures of personal property must be based on probable cause. See ante, at 700-702. Despite this recognition, the Court employs a balancing test drawn from Terry to conclude that personal effects may be seized based on reasonable suspicion. See ante, at 703-706.5 *718In Dunaway v. New York, 442 U. S. 200 (1979), the Court stated that “[t]he narrow intrusions involved in [Terry and its progeny] were judged by a balancing test rather than by the general principle that Fourth Amendment seizures must be supported by the ‘long-prevailing standards’ of probable cause . . . only because these intrusions fell far short of the kind of intrusion associated with an arrest.” Id., at 212. As Dunaway suggests, the use of a balancing test in this case is inappropriate. First, the intrusion involved in this case is no longer the “narrow” one contemplated by the Terry line of cases. See supra, at 717. In addition, the intrusion involved in this case involves not only the seizure of a person, but also the seizure of property. As noted, supra, at 711-712, Terry and its progeny did not address seizures of property. Those cases left unchanged the rule that seizures of property must be based on probable cause. See supra, at 716-717. The Terry balancing test should not be wrenched from its factual and conceptual moorings.
There are important reasons why balancing inquiries should not be conducted except in the most limited circumstances. Terry and the cases that followed it established “isolated exceptions to the general rule that the Fourth Amendment itself has already performed the constitutional balance between police objectives and personal privacy.” Michigan v. Summers, 452 U. S. 692, 706 (1981) (Stewart, J., dissenting). “[T]he protections intended by the Framers could all too easily disappear in the consideration and balancing of the multifarious circumstances presented by different cases, especially when that balancing may be done in the first instance by police officers engaged in the ‘often competitive enterprise of ferreting out crime.’ ” Dunaway v. New York, *719supra, at 213, quoting Johnson v. United States, 333 U. S. 10, 14 (1948). The truth of this proposition is apparent when one considers that the Court today has employed a balancing test "to swallow the general rule that [seizures of property] are ‘reasonable’ only if based on probable cause.” 442 U. S., at 213. Justice Blackmun’s concern over “an emerging tendency on the part of the Court to convert the Terry decision into a general statement that the Fourth Amendment requires only that any seizure be reasonable,” post, at 721 (Blackmun, J., concurring in judgment) (footnote omitted), is certainly justified.
Ill
The Court also suggests today, in a discussion unnecessary to the judgment, that exposure of respondent’s luggage to a narcotics detection dog “did not constitute a ‘search’ within the meaning of the Fourth Amendment.” Ante, at 707. In the District Court, respondent did “not contest the validity of sniff searches per se. . . .” 498 F. Supp. 1217, 1228 (EDNY 1980). The Court of Appeals did not reach or discuss the issue. It was not briefed or argued in this Court. In short, I agree with Justice Blackmun that the Court should not address the issue. See post, at 723-724 (Blackmun, J., concurring in judgment).
I also agree with Justice Blackmun’s suggestion, ibid., that the issue is more complex than the Court’s discussion would lead one to believe. As Justice Stevens suggested in objecting to “unnecessarily broad dicta” in United States v. Knotts, 460 U. S. 276 (1983), the use of electronic detection techniques that enhance human perception implicates “especially sensitive concerns.” Id., at 288 (opinion concurring in judgment). Obviously, a narcotics detection dog is not an electronic detection device. Unlike the electronic “beeper” in Knotts, however, a dog does more than merely allow the police to do more efficiently what they could do using only their own senses. A dog adds a new and previously unobtainable dimension to human perception. The use of dogs, therefore, represents a greater intrusion into an individual’s *720privacy. Such use implicates concerns that are at least as sensitive as those implicated by the use of certain electronic detection devices. Cf. Katz v. United States, 389 U. S. 347 (1967).
I have expressed the view that dog sniffs of people constitute searches. See Doe v. Renfrow, 451 U. S. 1022, 1025-1026 (1981) (Brennan, J., dissenting from denial of certio-rari). In Doe, I suggested that sniffs of inanimate objects might present a different case. Id., at 1026, n. 4. In any event, I would leave the determination of whether dog sniffs of luggage amount to searches, and the subsidiary question of what standards should govern such intrusions, to a future case providing an appropriate, and more informed, basis for deciding these questions.
IV
Justice Douglas was the only dissenter in Terry. He stated that “[tjhere have been powerful hydraulic pressures throughout our history that bear heavily on the Court to water down constitutional guarantees and give the police the upper hand.” 392 U. S., at 39 (dissenting opinion). Today, the Court uses Terry as a justification for submitting to these pressures. Their strength is apparent, for even when the Court finds that an individual’s Fourth Amendment rights have been violated it cannot resist the temptation to weaken the protections the Amendment affords.
The “seizure” at issue in Terry v. Ohio was the actual physical restraint imposed on the suspect. 392 U. S., at 19. The Court assumed that the officer's initial approach and questioning of the suspect did not amount to a “seizure.” Id., at 19, n. 16. The Court acknowledged, however, that “seizures” may occur irrespective of the imposition of actual physical restraint. The Court stated that “[i]t must be recognized that whenever a police officer accosts an individual and restrains his freedom to *712walk away, he has ‘seized’ that person.” Id,., at 16. See also id., at 19, n. 16. This standard, however, is easier to state than it is to apply. Compare United States v. Mendenhall, 446 U. S. 544, 550-557 (1980) (opinion of Stewart, J.), with Florida v. Royer, 460 U. S. 491, 511-512 (1983) (Brennan, J., concurring in result).
The stops “‘usually consumefd] no more than a minute.’” United States v. Brignoni-Ponce, 422 U. S., at 880.
In Michigan v. Summers, 452 U. S. 692 (1981), the Court relied on Terry and its progeny to hold that “a warrant to search for contraband founded on probable cause implicitly carries with it the limited authority to detain the occupants of the premises while a proper search is conducted.” 452 U. S., at 705 (footnotes omitted). The Court also relied on Terry in Pennsylvania v. Mimms, 434 U. S. 106 (1977), to uphold an officer’s order to an individual to get out of his car following a lawful stop of the vehicle. Both Summers and Mimms focused on seizures of people.
Putting aside the legality of the independent seizure of the luggage, the Court correctly points out that the seizure of luggage “can effectively restrain the person” beyond the initial stop “since he is subjected to the possible disruption of his travel plans in order to remain with his luggage or to arrange for its return.” Ante, at 708 (footnote omitted).
To the extent that the Court relies on United States v. Van Leeuwen, 397 U. S. 249 (1970), as support for its conclusion, see ante, at 705-706, n. 6, such reliance is misplaced. As the Court itself points out, the holding in Van Leeuvjen was expressly limited to the facts of that case. Ante, at 705, n. 6. Moreover, the Court of Appeals more than adequately distin*718guished Van Leewwen. See 660 F. 2d 44, 52-63 (CA21981). As the court stated: “Unlike the dispossession of hand baggage in a passenger’s custody, which constitutes a substantial intrusion, the mere detention of mail not in his custody or control amounts to at most a minimal or technical interference with his person or effects, resulting in no personal deprivation at all.” Ibid.