OCTOBER TERM, 2000

															Syllabus

															CITY OF INDIANAPOLIS ET AL. v. EDMOND ET AL.

															CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE SEVENTH
CIRCUIT

															No. 99-1030. Argued October 3, 2000-Decided November 28,
2000

															Petitioner city operates vehicle checkpoints on its roads in an
effort to interdict unlawful drugs. Respondents, who were each
stopped at such a checkpoint, filed suit, claiming that the
roadblocks violated the Fourth Amendment. The District Court denied
respondents a preliminary injunction, but the Seventh Circuit
reversed, holding that the checkpoints contravened the Fourth
Amendment. Held: Because the checkpoint program's primary purpose is
indistinguishable from the general interest in crime control, the
checkpoints violate the Fourth Amendment. Pp. 37-48.

															(a) The rule that a search or seizure is unreasonable under the
Fourth Amendment absent individualized suspicion of wrongdoing has
limited exceptions. For example, this Court has upheld brief,
suspicionless seizures at a fixed checkpoint designed to intercept
illegal aliens, United States v. Martinez-Fuerte, 428 U. S. 543 ,
and at a sobriety checkpoint aimed at removing drunk drivers from
the road, Michigan Dept. of State Police v. Sitz, 496 U. S. 444 .
The Court has also suggested that a similar roadblock to verify
drivers' licenses and registrations would be permissible to serve a
highway safety interest. Delaware v. Prouse, 440 U. S. 648 , 663.
However, the Court has never approved a checkpoint program whose
primary purpose was to detect evidence of ordinary criminal
wrongdoing. Pp. 37-40.

															(b) The latter purpose is what principally distinguishes the
checkpoints at issue from those the Court has previously approved,
which were designed to serve purposes closely related to the
problems of policing the border or the necessity of ensuring
roadway safety. Petitioners state that the Sitz and Martinez-Fuerte checkpoints had the same ultimate purpose of
arresting those suspected of committing crimes. Securing the border
and apprehending drunken drivers are law enforcement activities,
and authorities employ arrests and criminal prosecutions to pursue
these goals. But if this case were to rest at such a high level of
generality, there would be little check on the authorities' ability
to construct roadblocks for almost any conceivable law enforcement
purpose. The checkpoint program is also not justified by the severe
and intractable nature of the drug problem. The gravity of the
threat alone 33 cannot be dispositive of questions concerning what means law
enforcement may employ to pursue a given purpose. Rather, in
determining whether individualized suspicion is required, the Court
must consider the nature of the interests threatened and their
connection to the particular law enforcement practices at issue.
Nor can the checkpoints' purpose be rationalized in terms of a
highway safety concern similar to that in Sitz, or merely
likened to the antismuggling purpose in MartinezFuerte. Neither Whren v. United States, 517 U. S. 806 , nor Bond v. United States, 529 U. S. 334 , precludes
an inquiry into the checkpoint program's purposes. And if the
program could be justified by its lawful secondary purposes of
keeping impaired motorists off the road and verifying licenses and
registrations, authorities would be able to establish checkpoints
for virtually any purpose so long as they also included a license
or sobriety check. That is why the Court must determine the primary
purpose of the checkpoint program. This holding does not alter the
constitutional status of the checkpoints approved in Sitz and Martinez-Fuerte, or the type of checkpoint suggested in Prouse. It also does not affect the validity of border
searches or searches in airports and government buildings, where
the need for such measures to ensure public safety can be
particularly acute. Nor does it impair police officers' ability to
act appropriately upon information that they properly learn during
a checkpoint stop justified by a lawful primary purpose. Finally,
the purpose inquiry is to be conducted only at the programmatic
level and is not an invitation to probe the minds of individual
officers acting at the scene. Pp. 40-48. 183 F.3d
659 , affirmed.

															O'CONNOR, J., delivered the opinion of the Court, in which
STEVENS, KENNEDY, SOUTER, GINSBURG, and BREYER, JJ., joined.
REHNQUIST, C. J., filed a dissenting opinion, in which THOMAS, J.,
joined, and in which SCALIA, J., joined as to Part I, post, p. 48. THOMAS, J., filed a dissenting opinion, post, p.
56.

															A. Scott Chinn argued the cause for petitioners. With him on the
briefs were Anthony W Overholt, Matthew R. Gutwein, and Thomas M.
Fisher.

															Patricia A. Millett argued the cause for the United States as
amicus curiae urging reversal. With her on the brief were Solicitor
General Waxman, Assistant Attorney General Robinson, and Deputy
Solicitor General Dreeben. 34 Kenneth J. Falk argued the cause for respondents. With him on
the brief were Jacquelyn E. Bowie, Sean C. Lemieux, and Steven R.
Shapiro. *

															JUSTICE O'CONNOR delivered the opinion of the Court.

															In Michigan Dept. of State Police v. Sitz, 496 U. S. 444 (1990), and United States v. Martinez-Fuerte, 428 U. S. 543 (1976), we held that brief, suspicionless seizures at highway
checkpoints for the purposes of combating drunk driving and
intercepting illegal immigrants were constitutional. We now
consider the constitutionality of a highway checkpoint program
whose primary purpose is the discovery and interdiction of illegal
narcotics.

															I

															In August 1998, the city of Indianapolis began to operate
vehicle checkpoints on Indianapolis roads in an effort to interdict
unlawful drugs. The city conducted six such roadblocks between
August and November that year, stopping

															*Briefs of amici curiae urging reversal were filed for
the State of Kansas et al. by Carla J. Stovall, Attorney General of Kansas, Stephen R. McAllister, State
Solicitor, Jared S. Maag, Assistant Attorney General,
and John M. Bailey, Chief State's Attorney of Connecticut,
and by the Attorneys General for their respective States as
follows: Bill Pryor of Alabama, Janet Napolitano of
Arizona, Mark Pryor of Arkansas, Bill Lockyer of
California, Robert A. Butterworth of Florida, James E.
Ryan of Illinois, Karen M. Freeman-Wilson of Indiana, Thomas J. Miller of Iowa, Michael C. Moore of Mississippi, Don Stenberg of Nebraska, W
A. Drew Edmondson of Oklahoma, Jan Graham of Utah, and Mark L. Earley of Virginia; for the National League of
Cities et al. by Richard Ruda and James I. Crowley; and for the Washington Legal Foundation et al. by Daniel J. Popeo. Briefs of amici curiae urging affirmance were filed for
the National Association of Criminal Defense Lawyers et al. by Wesley MacNeil Oliver and Barbara Bergman; and for
the Rutherford Institute by John W Whitehead and Steven
H. Aden. Wayne W Schmidt, James P. Manak, Richard Weintraub, and Bernard
J. Farber filed a brief for Americans for Effective Law
Enforcement, Inc., et al. as amici curiae. 35 1,161 vehicles and arresting 104 motorists. Fifty-five arrests
were for drug-related crimes, while 49 were for offenses unrelated
to drugs. Edmond v. Goldsmith, 183 F.3d
659 , 661 (CA7 1999). The overall "hit rate" of the program was
thus approximately nine percent.

															The parties stipulated to the facts concerning the operation of
the checkpoints by the Indianapolis Police Department (IPD) for
purposes of the preliminary injunction proceedings instituted
below. At each checkpoint location, the police stop a predetermined
number of vehicles. Approximately 30 officers are stationed at the
checkpoint. Pursuant to written directives issued by the chief of
police, at least one officer approaches the vehicle, advises the
driver that he or she is being stopped briefly at a drug
checkpoint, and asks the driver to produce a license and
registration. The officer also looks for signs of impairment and
conducts an open-view examination of the vehicle from the outside.
A narcoticsdetection dog walks around the outside of each stopped
vehicle.

															The directives instruct the officers that they may conduct a
search only by consent or based on the appropriate quantum of
particularized suspicion. The officers must conduct each stop in
the same manner until particularized suspicion develops, and the
officers have no discretion to stop any vehicle out of sequence.
The city agreed in the stipulation to operate the checkpoints in
such a way as to ensure that the total duration of each stop,
absent reasonable suspicion or probable cause, would be five
minutes or less.

															The affidavit of Indianapolis Police Sergeant Marshall DePew,
although it is technically outside the parties' stipulation,
provides further insight concerning the operation of the
checkpoints. According to Sergeant DePew, checkpoint locations are
selected weeks in advance based on such considerations as area
crime statistics and traffic flow. The checkpoints are generally
operated during daylight hours and are identified with lighted
signs reading, "'NARCOTICS 36 CHECKPOINT __ MILE AHEAD, NARCOTICS K-9 IN USE, BE PREPARED TO
STOP.'" App. to Pet. for Cert. 57a. Once a group of cars has been
stopped, other traffic proceeds without interruption until all the
stopped cars have been processed or diverted for further
processing. Sergeant DePew also stated that the average stop for a
vehicle not subject to further processing lasts two to three
minutes or less.

															Respondents James Edmond and J oell Palmer were each stopped at
a narcotics checkpoint in late September 1998. Respondents then
filed a lawsuit on behalf of themselves and the class of all
motorists who had been stopped or were subject to being stopped in
the future at the Indianapolis drug checkpoints. Respondents
claimed that the roadblocks violated the Fourth Amendment of the
United States Constitution and the search and seizure provision of
the Indiana Constitution. Respondents requested declaratory and
injunctive relief for the class, as well as damages and attorney's
fees for themselves.

															Respondents then moved for a preliminary injunction.

															Although respondents alleged that the officers who stopped them
did not follow the written directives, they agreed to the
stipulation concerning the operation of the checkpoints for
purposes of the preliminary injunction proceedings. The parties
also stipulated to certification of the plaintiff class. The United
States District Court for the Southern District of Indiana agreed
to class certification and denied the motion for a preliminary
injunction, holding that the checkpoint program did not violate the
Fourth Amendment. Edmond v. Goldsmith, 38 F. Supp. 2d 1016 (1998).
A divided panel of the United States Court of Appeals for the
Seventh Circuit reversed, holding that the checkpoints contravened
the Fourth Amendment. 183 F.3d
659 (1999). The panel denied rehearing. We granted certiorari,
528 U. S. 1153 (2000), and now affirm. 37 II

															The Fourth Amendment requires that searches and seizures be
reasonable. A search or seizure is ordinarily unreasonable in the
absence of individualized suspicion of wrongdoing. Chandler v. Miller, 520
U. S. 305 , 308 (1997). While such suspicion is not an
"irreducible" component of reasonableness, Martinez-Fuerte, 428 U. S., at 561, we have recognized only limited circumstances in
which the usual rule does not apply. For example, we have upheld
certain regimes of suspicionless searches where the program was
designed to serve "special needs, beyond the normal need for law
enforcement." See, e. g., Vernonia School Dist. J,7J v. Acton, 515 U.
S. 646 (1995) (random drug testing of studentathletes); Treasury Employees v. Von Raab, 489 U. S. 656 (1989)
(drug tests for United States Customs Service employees seeking
transfer or promotion to certain positions); Skinner v. Railway Labor Executives' Assn., 489 U. S. 602 (1989)
(drug and alcohol tests for railway employees involved in train
accidents or found to be in violation of particular safety
regulations). We have also allowed searches for certain
administrative purposes without particularized suspicion of
misconduct, provided that those searches are appropriately limited.
See, e. g., New York v. Burger, 482 U. S. 691 , 702-704
(1987) (warrantless administrative inspection of premises of
"closely regulated" business); Michigan v. Tyler, 436 U. S. 499 ,
507-509, 511-512 (1978) (administrative inspection of fire-damaged
premises to determine cause of blaze); Camara v. Municipal Court of City and County of San Francisco, 387 U. S. 523 ,
534-539 (1967) (administrative inspection to ensure compliance with
city housing code).

															We have also upheld brief, suspicionless seizures of motorists
at a fixed Border Patrol checkpoint designed to intercept illegal
aliens, Martinez-Fuerte, supra, and at a sobriety checkpoint
aimed at removing drunk drivers from the road, Michigan Dept. of
State Police v. Sitz, 496 U. S. 444 (1990). In
addition, in Delaware v. Prouse, 440 U. S. 648 , 663
(1979), 38 we suggested that a similar type of roadblock with the purpose
of verifying drivers' licenses and vehicle registrations would be
permissible. In none of these cases, however, did we indicate
approval of a checkpoint program whose primary purpose was to
detect evidence of ordinary criminal wrongdoing.

															In Martinez-Fuerte, we entertained Fourth Amendment
challenges to stops at two permanent immigration checkpoints
located on major United States highways less than 100 miles from
the Mexican border. We noted at the outset the particular context
in which the constitutional question arose, describing in some
detail the "formidable law enforcement problems" posed by the
northbound tide of illegal entrants into the United States. 428 U.
S., at 551-554. These problems had also been the focus of several
earlier cases addressing the constitutionality of other Border
Patrol traffic-checking operations. See United States v. Ortiz, 422 U.
S. 891 (1975); United States v. Brignoni-Ponce, 422 U. S. 873 (1975); Almeida-Sanchez v. United States, 413 U. S. 266 (1973). In Martinez-Fuerte, we found that the balance tipped in favor
of the Government's interests in policing the Nation's borders. 428
U. S., at 561-564. In so finding, we emphasized the difficulty of
effectively containing illegal immigration at the border itself. Id., at 556. We also stressed the impracticality of the
particularized study of a given car to discern whether it was
transporting illegal aliens, as well as the relatively modest
degree of intrusion entailed by the stops. Id., at
556-564.

															Our subsequent cases have confirmed that considerations
specifically related to the need to police the border were a
significant factor in our Martinez-Fuerte decision. For
example, in United States v. Montoya de Hernandez, 473 U. S. 531 ,538
(1985), we counted Martinez-Fuerte as one of a number of
Fourth Amendment cases that "reflect longstanding concern for the
protection of the integrity of the border." Although the stops in Martinez-Fuerte did not occur at the 39 border itself, the checkpoints were located near the border and
served a border control function made necessary by the difficulty
of guarding the border's entire length. See Martinez-Fuerte,
supra, at 556.

															In Sitz, we evaluated the constitutionality of a Michigan
highway sobriety checkpoint program. The Sitz checkpoint
involved brief, suspicionless stops of motorists so that police
officers could detect signs of intoxication and remove impaired
drivers from the road. 496 U. S., at 447-448. Motorists who
exhibited signs of intoxication were diverted for a license and
registration check and, if warranted, further sobriety tests. Id., at 447. This checkpoint program was clearly aimed at
reducing the immediate hazard posed by the presence of drunk
drivers on the highways, and there was an obvious connection
between the imperative of highway safety and the law enforcement
practice at issue. The gravity of the drunk driving problem and the
magnitude of the State's interest in getting drunk drivers off the
road weighed heavily in our determination that the program was
constitutional. See id., at 451.

															In Prouse, we invalidated a discretionary, suspicionless
stop for a spot check of a motorist's driver's license and vehicle
registration. The officer's conduct in that case was
unconstitutional primarily on account of his exercise of
"standardless and unconstrained discretion." 440 U. S., at 661. We
nonetheless acknowledged the States' "vital interest in ensuring
that only those qualified to do so are permitted to operate motor
vehicles, that these vehicles are fit for safe operation, and hence
that licensing, registration, and vehicle inspection requirements
are being observed." Id., at 658. Accordingly, we suggested
that "[q]uestioning of all oncoming traffic at roadblock-type
stops" would be a lawful means of serving this interest in highway
safety. Id., at 663.

															We further indicated in Prouse that we considered the
purposes of such a hypothetical roadblock to be distinct from a
general purpose of investigating crime. The State prof- 40 fered the additional interests of "the apprehension of stolen
motor vehicles and of drivers under the influence of alcohol or
narcotics" in its effort to justify the discretionary spot check. Id., at 659, n. 18. We attributed the entirety of the latter
interest to the State's interest in roadway safety. Ibid. We
also noted that the interest in apprehending stolen vehicles may be
partly subsumed by the interest in roadway safety. Ibid. We
observed, however, that "[t]he remaining governmental interest in
controlling automobile thefts is not distinguishable from the
general interest in crime control." Ibid. Not only does the
common thread of highway safety thus run through Sitz and Prouse, but Prouse itself reveals a difference in the
Fourth Amendment significance of highway safety interests and the
general interest in crime control.

															III

															It is well established that a vehicle stop at a highway
checkpoint effectuates a seizure within the meaning of the Fourth
Amendment. See, e. g., Sitz, supra, at 450. The fact that
officers walk a narcotics-detection dog around the exterior of each
car at the Indianapolis checkpoints does not transform the seizure
into a search. See United States v. Place, 462 U. S. 696 , 707
(1983). Just as in Place, an exterior sniff of an automobile
does not require entry into the car and is not designed to disclose
any information other than the presence or absence of narcotics.
See ibid. Like the dog sniff in Place, a sniff by a
dog that simply walks around a car is "much less intrusive than a
typical search." Ibid. Cf. United States v. Turpin, 920 F.2d
1377 , 1385 (CA8 1990). Rather, what principally
distinguishes these checkpoints from those we have previously
approved is their primary purpose.

															As petitioners concede, the Indianapolis checkpoint program
unquestionably has the primary purpose of interdicting illegal
narcotics. In their stipulation of facts, the parties repeatedly
refer to the checkpoints as "drug checkpoints" and 41 describe them as "being operated by the City of Indianapolis in
an effort to interdict unlawful drugs in Indianapolis." App. to
Pet. for Cert. 51a-52a. In addition, the first document attached to
the parties' stipulation is entitled "DRUG CHECKPOINT CONTACT
OFFICER DIRECTIVES BY ORDER OF THE CHIEF OF POLICE." Id., at
53a. These directives instruct officers to "[a]dvise the citizen
that they are being stopped briefly at a drug checkpoint." Ibid. The second document attached to the stipulation is
entitled "1998 Drug Road Blocks" and contains a statistical
breakdown of information relating to the checkpoints conducted. Id., at 55a. Further, according to Sergeant DePew, the
checkpoints are identified with lighted signs reading, "'NARCOTICS
CHECKPOINT __ MILE AHEAD, NARCOTICS K-9 IN USE, BE PREPARED TO
STOP.'" Id., at 57a. Finally, both the District Court and
the Court of Appeals recognized that the primary purpose of the
roadblocks is the interdiction of narcotics. 38 F. Supp. 2d, at
1026 (noting that both parties "stress the primary purpose of the
roadblocks as the interdiction of narcotics" and that "[t]he IPD
has made it clear that the purpose for its checkpoints is to
interdict narcotics traffic"); 183 F. 3d, at 665 (observing that
"the City concedes that its proximate goal is to catch drug
offenders").

															We have never approved a checkpoint program whose primary
purpose was to detect evidence of ordinary criminal wrongdoing.
Rather, our checkpoint cases have recognized only limited
exceptions to the general rule that a seizure must be accompanied
by some measure of individualized suspicion. We suggested in Prouse that we would not credit the "general interest in
crime control" as justification for a regime of suspicionless
stops. 440 U. S., at 659, n. 18. Consistent with this suggestion,
each of the checkpoint programs that we have approved was designed
primarily to serve purposes closely related to the problems of
policing the border or the necessity of ensuring roadway safety.
Because the 42 primary purpose of the Indianapolis narcotics checkpoint program
is to uncover evidence of ordinary criminal wrongdoing, the program
contravenes the Fourth Amendment.

															Petitioners propose several ways in which the narcoticsdetection
purpose of the instant checkpoint program may instead resemble the
primary purposes of the checkpoints in Sitz and Martinez-Fuerte. Petitioners state that the checkpoints in
those cases had the same ultimate purpose of arresting those
suspected of committing crimes. Brief for Petitioners 22. Securing
the border and apprehending drunk drivers are, of course, law
enforcement activities, and law enforcement officers employ arrests
and criminal prosecutions in pursuit of these goals. See Sitz, 496 U. S., at 447, 450; Martinez-Fuerte, 428 U.
S., at 545-550. If we were to rest the case at this high level of
generality, there would be little check on the ability of the
authorities to construct roadblocks for almost any conceivable law
enforcement purpose. Without drawing the line at roadblocks
designed primarily to serve the general interest in crime control,
the Fourth Amendment would do little to prevent such intrusions
from becoming a routine part of American life.

															Petitioners also emphasize the severe and intractable nature of
the drug problem as justification for the checkpoint program. Brief
for Petitioners 14-17, 31. There is no doubt that traffic in
illegal narcotics creates social harms of the first magnitude. Cf. Von Raab, 489 U. S., at 668. The law enforcement problems
that the drug trade creates likewise remain daunting and complex,
particularly in light of the myriad forms of spin-off crime that it
spawns. Cf. M on toya de Hernandez, 473 U. S., at 538.
The same can be said of various other illegal activities, if only
to a lesser degree. But the gravity of the threat alone cannot be
dispositive of questions concerning what means law enforcement
officers may employ to pursue a given purpose. Rather, in
determining whether individualized suspicion is required, we must
consider the nature of the interests threatened and their con- 43 nection to the particular law enforcement practices at issue. We
are particularly reluctant to recognize exceptions to the general
rule of individualized suspicion where governmental authorities
primarily pursue their general crime control ends.

															Nor can the narcotics-interdiction purpose of the checkpoints be
rationalized in terms of a highway safety concern similar to that
present in Sitz. The detection and punishment of almost any
criminal offense serves broadly the safety of the community, and
our streets would no doubt be safer but for the scourge of illegal
drugs. Only with respect to a smaller class of offenses, however,
is society confronted with the type of immediate, vehicle-bound
threat to life and limb that the sobriety checkpoint in Sitz was designed to eliminate.

															Petitioners also liken the anticontraband agenda of the
Indianapolis checkpoints to the antismuggling purpose of the
checkpoints in Martinez-Fuerte. Brief for Petitioners 1516.
Petitioners cite this Court's conclusion in MartinezFuerte that the flow of traffic was too heavy to permit "particularized
study of a given car that would enable it to be identified as a
possible carrier of illegal aliens," 428 U. S., at 557, and claim
that this logic has even more force here. The problem with this
argument is that the same logic prevails any time a vehicle is
employed to conceal contraband or other evidence of a crime. This
type of connection to the roadway is very different from the close
connection to roadway safety that was present in Sitz and Prouse. Further, the Indianapolis checkpoints are far
removed from the border context that was crucial in Martinez-Fuerte. While the difficulty of examining each
passing car was an important factor in validating the law
enforcement technique employed in Martinez-Fuerte, this
factor alone cannot justify a regime of suspicionless searches or
seizures. Rather, we must look more closely at the nature of the
public interests that such a regime is designed principally to
serve. 44 The primary purpose of the Indianapolis narcotics checkpoints is
in the end to advance "the general interest in crime control," Prouse, 440 U. S., at 659, n. 18. We decline to suspend the
usual requirement of individualized suspicion where the police seek
to employ a checkpoint primarily for the ordinary enterprise of
investigating crimes. We cannot sanction stops justified only by
the generalized and everpresent possibility that interrogation and
inspection may reveal that any given motorist has committed some
crime.

															Of course, there are circumstances that may justify a law
enforcement checkpoint where the primary purpose would otherwise,
but for some emergency, relate to ordinary crime control. For
example, as the Court of Appeals noted, the Fourth Amendment would
almost certainly permit an appropriately tailored roadblock set up
to thwart an imminent terrorist attack or to catch a dangerous
criminal who is likely to flee by way of a particular route. See
183 F. 3d, at 662663. The exigencies created by these scenarios are
far removed from the circumstances under which authorities might
simply stop cars as a matter of course to see if there just happens
to be a felon leaving the jurisdiction. While we do not limit the
purposes that may justify a checkpoint program to any rigid set of
categories, we decline to approve a program whose primary purpose
is ultimately indistinguishable from the general interest in crime
control.l

															1 THE CHIEF JUSTICE'S dissent erroneously characterizes our
opinion as resting on the application of a "non-law-enforcement
primary purpose test." Post, at 53. Our opinion nowhere
describes the purposes of the Sitz and Martinez-Fuerte checkpoints as being "not primarily related
to criminal law enforcement." Post, at 50. Rather, our
judgment turns on the fact that the primary purpose of the
Indianapolis checkpoints is to advance the general interest in
crime control.

															THE CHIEF JUSTICE'S dissent also erroneously characterizes our
opinion as holding that the "use of a drug-sniffing dog ... annuls
what is otherwise plainly constitutional under our Fourth Amendment
jurisprudence." Post, at 48. Again, the constitutional
defect of the program is that its primary purpose is to advance the
general interest in crime control. 45 Petitioners argue that our prior cases preclude an inquiry into
the purposes of the checkpoint program. For example, they cite Whren v. United States, 517 U. S. 806 (1996), and Bond v. United States, 529 U. S. 334 (2000), to
support the proposition that "where the government articulates and
pursues a legitimate interest for a suspicionless stop, courts
should not look behind that interest to determine whether the
government's 'primary purpose' is valid." Brief for Petitioners 34;
see also id., at 9. These cases, however, do not control the
instant situation.

															In Whren, we held that an individual officer's subjective
intentions are irrelevant to the Fourth Amendment validity of a
traffic stop that is justified objectively by probable cause to
believe that a traffic violation has occurred. 517 U. S., at
810-813. We observed that our prior cases "foreclose any argument
that the constitutional reasonableness of traffic stops depends on
the actual motivations of the individual officers involved." Id., at 813. In so holding, we expressly distinguished cases
where we had addressed the validity of searches conducted in the
absence of probable cause. See id., at 811-812
(distinguishing Florida v. Wells, 495 U. S. 1 , 4 (1990)
(stating that "an inventory search must not be a ruse for a general
rummaging in order to discover incriminating evidence"), Colorado v. Bertine, 479 U. S. 367 , 372 (1987)
(suggesting that the absence of bad faith and the lack of a purely
investigative purpose were relevant to the validity of an inventory
search), and Burger, 482 U. S., at 716-717, n. 27 (observing
that a valid administrative inspection conducted with neither a
warrant nor probable cause did not appear to be a pretext for
gathering evidence of violations of the penal laws)). Whren therefore reinforces the principle that, while
"[sJubjective intentions play no role in ordinary, probablecause
Fourth Amendment analysis," 517 U. S., at 813, programmatic
purposes may be relevant to the validity of Fourth Amendment
intrusions undertaken pursuant to a 46 general scheme without individualized SuspICIOn. Accordingly, Whren does not preclude an inquiry into programmatic purpose
in such contexts. Cf. Chandler v. Miller, 520 U. S. 305 (1997); Treasury Employees v. Von Raab, 489 U. S. 656 (1989); Burger, supra; Michigan v. Tyler, 436 U. S. 499 (1978); Camara v. Municipal Court of City and County of San
Francisco, 387 U.
S. 523 (1967). It likewise does not preclude an inquiry into
programmatic purpose here.

															Last Term in Bond, we addressed the question whether a
law enforcement officer violated a reasonable expectation of
privacy in conducting a tactile examination of carry-on luggage in
the overhead compartment of a bus. In doing so, we simply noted
that the principle of Whren rendered the subjective intent
of an officer irrelevant to this analysis. 529 U. S., at 338, n. 2.
While, as petitioners correctly observe, the analytical rubric of Bond was not "ordinary, probable-cause Fourth Amendment
analysis," Whren, supra, at 813, nothing in Bond suggests that we would extend the principle of Whren to all
situations where individualized suspicion was lacking. Rather,
subjective intent was irrelevant in Bond because the inquiry
that our precedents required focused on the objective effects of
the actions of an individual officer. By contrast, our cases
dealing with intrusions that occur pursuant to a general scheme
absent individualized suspicion have often required an inquiry into
purpose at the programmatic level.

															Petitioners argue that the Indianapolis checkpoint program is
justified by its lawful secondary purposes of keeping impaired
motorists off the road and verifying licenses and registrations.
Brief for Petitioners 31-34. If this were the case, however, law
enforcement authorities would be able to establish checkpoints for
virtually any purpose so long as they also included a license or
sobriety check. For this reason, we examine the available evidence
to determine the primary purpose of the checkpoint program. While
we recognize the challenges inherent in a purpose inquiry,
courts 47 routinely engage in this enterprise in many areas of
constitutional jurisprudence as a means of sifting abusive
governmental conduct from that which is lawful. Cf. 183 F. 3d, at
665. As a result, a program driven by an impermissible purpose may
be proscribed while a program impelled by licit purposes is
permitted, even though the challenged conduct may be outwardly
similar. While reasonableness under the Fourth Amendment is
predominantly an objective inquiry, our special needs and
administrative search cases demonstrate that purpose is often
relevant when suspicionless intrusions pursuant to a general scheme
are at issue.2

															It goes without saying that our holding today does nothing to
alter the constitutional status of the sobriety and border
checkpoints that we approved in Sitz and Martinez-Fuerte, or of the type of traffic checkpoint that
we suggested would be lawful in Prouse. The
constitutionality of such checkpoint programs still depends on a
balancing of the competing interests at stake and the effectiveness
of the program. See Sitz, 496 U. S., at 450-455; Martinez-Fuerte, 428 U. S., at 556-564. When law enforcement
authorities pursue primarily general crime control purposes at
checkpoints such as here, however, stops can only be justified by
some quantum of individualized suspicion.

															Our holding also does not affect the validity of border searches
or searches at places like airports and government

															2 Because petitioners concede that the primary purpose of the
Indianapolis checkpoints is narcotics detection, we need not decide
whether the State may establish a checkpoint program with the
primary purpose of checking licenses or driver sobriety and a
secondary purpose of interdicting narcotics. Specifically, we
express no view on the question whether police may expand the scope
of a license or sobriety checkpoint seizure in order to detect the
presence of drugs in a stopped car. Cf. New Jersey v. T.
L. Q, 469 U. S.
325 , 341 (1985) (search must be "'reasonably related in scope
to the circumstances which justified the interference in the first
place'" (quoting Terry v. Ohio, 392 U. S. 1 , 20 (1968))); Michigan v. Clif ford, 464 U. S. 287 , 294-295
(1984) (plurality opinion). 48 buildings, where the need for such measures to ensure public
safety can be particularly acute. Nor does our opinion speak to
other intrusions aimed primarily at purposes beyond the general
interest in crime control. Our holding also does not impair the
ability of police officers to act appropriately upon information
that they properly learn during a checkpoint stop justified by a
lawful primary purpose, even where such action may result in the
arrest of a motorist for an offense unrelated to that purpose.
Finally, we caution that the purpose inquiry in this context is to
be conducted only at the programmatic level and is not an
invitation to probe the minds of individual officers acting at the
scene. Cf. Whren, supra. Because the primary purpose of the Indianapolis checkpoint
program is ultimately indistinguishable from the general interest
in crime control, the checkpoints violate the Fourth Amendment. The
judgment of the Court of Appeals is, accordingly, affirmed.

															It is so ordered.

															CHIEF JUSTICE REHNQUIST, with whom JUSTICE THOMAS joins, and
with whom JUSTICE SCALIA joins as to Part I, dissenting.

															The State's use of a drug-sniffing dog, according to the Court's
holding, annuls what is otherwise plainly constitutional under our
Fourth Amendment jurisprudence: brief, standardized,
discretionless, roadblock seizures of automobiles, seizures which
effectively serve a weighty state interest with only minimal
intrusion on the privacy of their occupants. Because these seizures
serve the State's accepted and significant interests of preventing
drunken driving and checking for driver's licenses and vehicle
registrations, and because there is nothing in the record to
indicate that the addition of the dog sniff lengthens these
otherwise legitimate seizures, I dissent. 49 I

															As it is nowhere to be found in the Court's opinion, I begin
with blackletter roadblock seizure law. "The principal protection
of Fourth Amendment rights at checkpoints lies in appropriate
limitations on the scope of the stop." United States v. Martinez-Fuerte, 428 U. S. 543 , 566-567
(1976). Roadblock seizures are consistent with the Fourth Amendment
if they are "carried out pursuant to a plan embodying explicit,
neutral limitations on the conduct of individual officers." Brown v. Texas, 443 U. S. 47 , 51 (1979).
Specifically, the constitutionality of a seizure turns upon "a
weighing of the gravity of the public concerns served by the
seizure, the degree to which the seizure advances the public
interest, and the severity of the interference with individual
liberty." Id., at 50-51.

															We first applied these principles in Martinez-Fuerte,
supra, which approved highway checkpoints for detecting illegal
aliens. In Martinez-Fuerte, we balanced the United States'
formidable interest in checking the flow of illegal immigrants
against the limited "objective" and "subjective" intrusion on the
motorists. The objective intrusion-the stop itself,l the brief
questioning of the occupants, and the visual inspection of the
car-was considered "limited" because "[n]either the vehicle nor its
occupants [were] searched." Id., at 558. Likewise, the
subjective intrusion, or the fear and surprise engendered in
law-abiding motorists by the nature of the stop, was found to be
minimal because the "regularized manner in which [the] established
checkpoints [were] operated [was] visible evidence, reassuring to
law-abiding motorists, that the stops [were] duly authorized and
believed to serve the public interest." Id., at 559. Indeed,
the standardized operation of the roadblocks was viewed as

															1 The record from one of the consolidated cases indicated that
the stops lasted between three and five minutes. See United
States v. MartinezFuerte, 428 U. S. 543 , 546-547
(1976). 50 markedly different from roving patrols, where the unbridled
discretion of officers in the field could result in unlimited
interference with motorists' use of the highways. Cf. United
States v. Brignoni-Ponce, 422 U. S. 873 (1975). And
although the decision in Martinez-Fuerte did not turn on the
checkpoints' effectiveness, the record in one of the consolidated
cases demonstrated that illegal aliens were found in 0.12 percent
of the stopped vehicles. See 428 U. S., at 554.

															In Michigan Dept. of State Police v. Sitz, 496 U. S. 444 (1990), we upheld the State's use of a highway sobriety checkpoint
after applying the framework set out in Martinez-Fuerte,
supra, and Brown v. Texas, supra. There, we
recognized the gravity of the State's interest in curbing drunken
driving and found the objective intrusion of the approximately
25-second seizure to be "slight." 496 U. S., at 451. Turning to the
subjective intrusion, we noted that the checkpoint was selected
pursuant to guidelines and was operated by uniformed officers. See
id., at 453. Finally, we concluded that the program effectively
furthered the State's interest because the checkpoint resulted in
the arrest of two drunk drivers, or 1.6 percent of the 126 drivers
stopped. See id., at 455-456.

															This case follows naturally from Martinez-Fuerte and Sitz. Petitioners acknowledge that the "primary purpose" of these
roadblocks is to interdict illegal drugs, but this fact should not
be controlling. Even accepting the Court's conclusion that the
checkpoints at issue in Martinez-Fuerte and Sitz were
not primarily related to criminal law enforcement,2 the

															2 This gloss, see ante, at 38-40, 41-43, is not at all
obvious. The respondents in Martinez-Fuerte were criminally
prosecuted for illegally transporting aliens, and the Court
expressly noted that "[i]nterdicting the flow of illegal entrants
from Mexico poses formidable law enforcement problems." 428 U. S.,
at 552. And the Sitz Court recognized that if an "officer's
observations suggest that the driver was intoxicated, an arrest
would be made." 496 U. S., at 447. But however persuasive the
distinction, the Court's opinion does not impugn the continuing
validity of Martinez-Fuerte and Sitz. See ante, at 47. 51 question whether a law enforcement purpose could support a
roadblock seizure is not presented in this case. The District Court
found that another "purpose of the checkpoints is to check driver's
licenses and vehicle registrations," App. to Pet. for Cert. 44a,
and the written directives state that the police officers are to
"[l]ook for signs of impairment," id., at 53a. The use of
roadblocks to look for signs of impairment was validated by Sitz, and the use of roadblocks to check for driver's
licenses and vehicle registrations was expressly recognized in Delaware v. Prouse, 440 U. S. 648 , 663
(1979).3 That the roadblocks serve these legitimate state interests
cannot be seriously disputed, as the 49 people arrested for
offenses unrelated to drugs can attest. Edmond v. Goldsmith, 183 F.3d
659 , 661 (CA7 1999). And it would be speculative to
conclude-given the District Court's findings, the written
directives, and the actual arrests-that petitioners would not have
operated these roadblocks but for the State's interest in
interdicting drugs.

															Because of the valid reasons for conducting these roadblock
seizures, it is constitutionally irrelevant that petitioners also
hoped to interdict drugs. In Whren v. United States, 517 U. S. 806 (1996), we held that an officer's subjective intent would not
invalidate an otherwise objectively justifiable stop of an
automobile. The reasonableness of an officer's discretionary
decision to stop an automobile, at issue in Whren, turns on
whether there is probable cause to believe that a traffic violation
has occurred. The reasonableness of highway checkpoints, at issue
here, turns on whether they effectively serve a significant state
interest with minimal intrusion on motorists. The stop in Whren was objectively reasonable because the police officers
had witnessed traffic violations; so too the roadblocks here are
objectively

															3 Several Courts of Appeals have upheld roadblocks that check
for driver's licenses and vehicle registrations. See, e. g., United States v. Galindo-Gonzales, 142 F.3d
1217 (CAlO 1998); United States v. McFayden, 865 F.2d
1306 (CADC 1989). 52 reasonable because they serve the substantial interests of
preventing drunken driving and checking for driver's licenses and
vehicle registrations with minimal intrusion on motorists.

															Once the constitutional requirements for a particular seizure
are satisfied, the subjective expectations of those responsible for
it, be it police officers or members of a city council, are
irrelevant. Cf. Scott v. United States, 436 U. S. 128 , 136 (1978)
("Subjective intent alone ... does not make otherwise lawful
conduct illegal or unconstitutional"). It is the objective effect
of the State's actions on the privacy of the individual that
animates the Fourth Amendment. See Bond v. United
States, 529 U. S.
334 , 338, n. 2 (2000) (applying Whren to determine if an
officer's conduct amounted to a "search" under the Fourth Amendment
because "the issue is not his state of mind, but the objective
effect of his actions"). Because the objective intrusion of a valid
seizure does not turn upon anyone's subjective thoughts, neither
should our constitutional analysis.4

															With these checkpoints serving two important state interests,
the remaining prongs of the Brown v. Texas balancing
test are easily met. The seizure is objectively reasonable as it
lasts, on average, two to three minutes and does not involve a
search. App. to Pet. for Cert. 57a. The subjective intrusion is
likewise limited as the checkpoints are clearly marked and operated
by uniformed officers who are directed to stop every vehicle in the
same manner. Ibid. The only difference between this case and Sitz is the presence of the dog. We have already held,
however, that a "sniff test" by a trained narcotics dog is not a
"search" within the meaning of the Fourth Amendment because it does
not require physical intrusion of the object being sniffed and it
does not ex-

															4 Of course we have looked to the purpose of the program in
analyzing the constitutionality of certain suspicionless searches.
As discussed in Part II, infra, that doctrine has never been
applied to seizures of automobiles. 53 pose anything other than the contraband items. United
States v. Place, 462 U. S. 696 , 706-707
(1983). And there is nothing in the record to indicate that the dog
sniff lengthens the stop. Finally, the checkpoints' success rate-49
arrests for offenses unrelated to drugs-only confirms the State's
legitimate interests in preventing drunken driving and ensuring the
proper licensing of drivers and registration of their vehicles. 183
F. 3d, at 661.5

															These stops effectively serve the State's legitimate interests;
they are executed in a regularized and neutral manner; and they
only minimally intrude upon the privacy of the motorists. They
should therefore be constitutional.

															II

															The Court, unwilling to adopt the straightforward analysis that
these precedents dictate, adds a new non-Iawenforcement primary
purpose test lifted from a distinct area of Fourth Amendment
jurisprudence relating to the searches of homes and
businesses. As discussed above, the question that the Court answers
is not even posed in this case given the accepted reasons for the
seizures. But more fundamentally, whatever sense a
non-law-enforcement primary purpose test may make in the search
setting, it is ill suited to brief roadblock seizures, where we
have consistently looked at "the scope of the stop" in assessing a
program's constitutionality. Martinez-Fuerte, 428 U. S., at
567.

															We have already rejected an invitation to apply the
nonlaw-enforcement primary purpose test that the Court now finds so
indispensable. The respondents in Sitz argued that the Brown v. Texas balancing test was not the "proper
method of analysis" with regards to roadblock seizures: "Respondents argue that there must be a showing of some special
governmental need 'beyond the normal 5 Put in statistical terms, 4.2 percent of the 1,161 motorists
stopped were arrested for offenses unrelated to drugs. 54 need' for criminal law enforcement before a balancing analysis
is appropriate, and that [the State] ha[s] demonstrated no such
special need. "But it is perfectly plain from a reading of [Treasury
Employees v.] Von Raab[, 489 U. S. 656 (1989)],
which cited and discussed with approval our earlier decision in United States v. Martinez-Fuerte, 428 U. S. 543 (1976),
that it was in no way designed to repudiate our prior cases dealing
with police stops of motorists on public highways. Martinez-Fuerte, supra, which utilized a balancing analysis
in approving highway checkpoints for detecting illegal aliens, and Brown v. Texas, supra, are the relevant authorities
here." 496 U. S., at 449, 450. Considerations of stare decisis aside, the "perfectly
plain" reason for not incorporating the "special needs" test in our
roadblock seizure cases is that seizures of automobiles "deal
neither with searches nor with the sanctity of private dwellings,
ordinarily afforded the most stringent Fourth Amendment
protection." Martinez-Fuerte, supra, at 561.

															The "special needs" doctrine, which has been used to uphold
certain suspicionless searches performed for reasons unrelated to
law enforcement, is an exception to the general rule that a search
must be based on individualized suspicion of wrongdoing. See, e.
g., Skinner v. Railway Labor Executives' Assn., 489 U. S. 602 (1989)
(drug test search); Camara v. Municipal Court of City and
County of San Francisco, 387 U. S. 523 (1967)
(home administrative search). The doctrine permits intrusions into
a person's body and home, areas afforded the greatest Fourth
Amendment protection. But there were no such intrusions here.

															"[O]ne's expectation of privacy in an automobile and of freedom
in its operation are significantly different from the traditional
expectation of privacy and freedom in one's residence." Martinez-Fuerte, supra, at 561. This is because
"[a]utomobiles, unlike homes, are subjected to pervasive and
continuing governmental regulation and controls." South 55 Dakota v. Opperman, 428 U. S. 364 , 368
(1976); see also New York v. Class, 475 U. S. 106 , 113 (1986)
("[A]utomobiles are justifiably the subject of pervasive regulation
by the State"); Cardwell v. Lewis, 417 U. S. 583 , 590 (1974)
("One has a lesser expectation of privacy in a motor vehicle
because its function is transportation and it seldom serves as
one's residence or as the repository of personal effects"). The
lowered expectation of privacy in one's automobile is coupled with
the limited nature of the intrusion: a brief, standardized,
nonintrusive seizure.6 The brief seizure of an automobile can
hardly be compared to the intrusive search of the body or the home.
Thus, just as the "special needs" inquiry serves to both define and
limit the permissible scope of those searches, the Brown v. Texas balancing test serves to define and limit the
permissible scope of automobile seizures.

															Because of these extrinsic limitations upon roadblock seizures,
the Court's newfound non-law-enforcement primary purpose test is
both unnecessary to secure Fourth Amendment rights and bound to
produce wide-ranging litigation over the "purpose" of any given
seizure. Police designing highway roadblocks can never be sure of
their validity, since a jury might later determine that a forbidden
purpose exists. Roadblock stops identical to the one that we upheld
in Sitz 10 years ago, or to the one that we upheld 24 years
ago in Martinez-Fuerte, may now be challenged on the grounds
that they have some concealed forbidden purpose.

															Efforts to enforce the law on public highways used by millions
of motorists are obviously necessary to our society. The Court's
opinion today casts a shadow over what had been assumed, on the
basis of stare decisis, to be a perfectly lawful activity.
Conversely, if the Indianapolis police had assigned a different
purpose to their activity here, but in no way changed what was done
on the ground to individual

															6 This fact distinguishes the roadblock seizure of an automobile
from an inventory search of an automobile. Cf. Colorado v. Bertine, 479
U. S. 367 (1987) (automobile inventory search). 56 motorists, it might well be valid. See ante, at 47, n. 2.
The Court's non-law-enforcement primary purpose test simply does
not serve as a proxy for anything that the Fourth Amendment is, or
should be, concerned about in the automobile seizure context.

															Petitioners' program complies with our decisions regarding
roadblock seizures of automobiles, and the addition of a dog sniff
does not add to the length or the intrusion of the stop. Because
such stops are consistent with the Fourth Amendment, I would
reverse the decision of the Court of Appeals.

															JUSTICE THOMAS, dissenting.

															Taken together, our decisions in Michigan Dept. of State
Police v. Sitz, 496 U. S. 444 (1990), and United States v. Martinez-Fuerte, 428 U. S. 543 (1976),
stand for the proposition that suspicionless roadblock seizures are
constitutionally permissible if conducted according to a plan that
limits the discretion of the officers conducting the stops. I am
not convinced that Sitz and Martinez-Fuerte were
correctly decided. Indeed, I rather doubt that the Framers of the
Fourth Amendment would have considered "reasonable" a program of
indiscriminate stops of individuals not suspected of
wrongdoing.

															Respondents did not, however, advocate the overruling of Sitz and Martinez-Fuerte, and I am reluctant to
consider such a step without the benefit of briefing and argument.
For the reasons given by THE CHIEF JUSTICE, I believe that those
cases compel upholding the program at issue here. I, therefore,
join his opinion.

Summary: The Supreme Court ruled that the city's vehicle checkpoint program, aimed at interdicting unlawful drugs, violated the Fourth Amendment as its primary purpose was indistinguishable from general crime control. The Court distinguished this case from previous approved checkpoints for border control and roadway safety, emphasizing the need for individualized suspicion and consideration of the nature of interests threatened. Justice Thomas dissented, questioning the reasonableness of suspicionless roadblock seizures and the Court's non-law-enforcement primary purpose test.