POSNER, Chief Judge.
A class action has been brought to enjoin the City of Indianapolis from setting up roadblocks to catch drug offenders, a practice that the plaintiffs claim violates the Fourth Amendment. The plaintiffs’ motion for a preliminary injunction was denied on the ground that the City’s practice is lawful, precipitating this interlocutory appeal under 28 U.S.C. § 1292(a)(1). The legality of drug roadblocks has divided the other courts that have been asked to decide the issue. Compare United States v. Huguenin, 154 F.3d 547, 554-55 (6th Cir.1998); United States v. Morales-Zamora, 974 F.2d 149 (10th Cir.1992); Galberth v. United States, 590 A.2d 990 (D.C.1991), and Wilson v. Commonwealth, 29 Va.App. 63, 509 S.E.2d 540 (1999), which held them illegal, with Merrett v. Moore, 58 F.3d 1547 (11th Cir.1995), and State v. Damask, 936 S.W.2d 565 (Mo.1996), which held them legal. This is our first case. Because it was decided by the district court on a very skimpy stipulation of facts, our ruling on the legality of the City’s program is necessarily tentative.
Six times between August and November of last year, the City’s police department set up roadblocks on Indianapolis streets to catch drug offenders. A total of 1,161 cars were stopped at these roadblocks — for how long is unclear but the police endeavor to operate the checkpoints in such a manner that the stop does not exceed five minutes. During the stop, the police demand the driver’s license and car registration, peer through the car’s windows into its interior, and lead a drug-sniffing dog around the car. The stopping of the 1,161 vehicles resulted in 55 drug-related arrests, meaning that 5 percent of the total number of stops resulted in successful drug “hits,” and 49 arrests for conduct unrelated to drugs, such as ■ driving with an expired driver’s license, for .an overall hit rate of 9 percent. The City is continuing the program.
Stopping a car at a roadblock is a seizure within the meaning of the Fourth Amendment, Whren v. United States, 517 U.S. 806, 809-10, 116 S.Ct. 1769, 135 L.Ed.2d 89 (1996); Michigan Dept. of State Police v. Sitz, 496 U.S. 444, 450, 110 S.Ct. 2481, 110 L.Ed.2d 412 (1990), even though the sequel — the peering into the car windows and the sniffing of the car by the dog outside — does not rise to the level of a search as that term of the amendment has been interpreted by the Supreme Court. United States v. Place, 462 U.S. 696, 707, 103 S.Ct. 2637, 77 L.Ed.2d 110 (1983); Texas v. Brown, 460 U.S. 730, 739-40, 103 S.Ct. 1535, 75 L.Ed.2d 502 (1983); United States v. Ware, 914 F.2d 997, 1000 (7th Cir.1990); United States v. Rodriguez-Morales, 929 F.2d 780, 788-89 (1st Cir.1991). Whether the seizures effected by Indianapolis’s drug roadblocks are reasonable may depend on whether reasonableness is to be assessed at the level of the entire program or of the individual stop. If the former, these roadblocks probably are legal, given the high “hit” rate and the only modestly intrusive character of the stops. In many Fourth Amendment contexts, the reasonableness of a practice is held to depend on the balance between its benefits (usually non-pecuniary) and its costs (ditto). E.g., Wyoming v. Houghton, — U.S. -, -, 119 S.Ct. 1297, 1300, 143 L.Ed.2d 408 (1999); Whren v. United States, supra, 517 U.S. at 817, 116 S.Ct. 1769; Skinner v. Railway Labor Executives’ Ass’n, 489 U.S. 602, 619, 109 S.Ct. 1402, 103 L.Ed.2d 639 (1989); Camara v. Municipal Court, 387 U.S. 523, 536-37, 87 S.Ct. 1727, 18 L.Ed.2d 930 (1967); Dimeo v. Griffin, 943 F.2d 679, 681 (7th Cir.1991) (en banc). The benefits of a random system of searches or seizures, such as vehicle stops pursuant to a roadblock system, are a function of, first, the probability that the stop will result in [662]*662an arrest or a seizure of contraband or evidence of crime, and, second, the gain to the achievement of a lawful governmental goal that such an arrest or seizure will produce. The costs are a function of the harm that the stop will cause to the property or privacy of the people whose cars are stopped. In the case of Indianapolis’s drug-roadblock program, the probability of a “hit” is high .(vastly higher than, for example, the probability of a hit as a result of the screening of embarking passengers and their luggage at airports, see National Treasury Employees Union v. Von Raab, 489 U.S. 656, 675 n. 3, 109 S.Ct. 1384, 103 L.Ed.2d 685 (1989)), and the deterrence of drug offenses produced by these hits advances the strong national, state, and local policy of discouraging the illegal use of controlled substances. The cost — in delay, anxiety, and invasion of privacy — to the drivers and passengers stopped for five minutes at a roadblock and subjected to a visual inspection of the interior and a sniff by a dog is small, though it is greater than the cost of the normal airport screening and (like that screening) is incurred in all stops while the benefit from the program is obtained only when there is a hit.
But courts do not usually assess reasonableness at the program level when they are dealing with searches related to general criminal law enforcement, see, e.g., Whren v. United States, supra, 517 U.S. at 810, 116 S.Ct. 1769, rather than to primarily civil regulatory programs for the protection of health, safety, and the integrity of our borders. E.g., Michigan v. Tyler, 436 U.S. 499, 504-06, 98 S.Ct. 1942, 56 L.Ed.2d 486 (1978); United States v. Martinez-Fuerte, 428 U.S. 543, 96 S.Ct. 3074, 49 L.Ed.2d 1116 (1976); Camara v. Municipal Court, supra; Platteville Area Apartment Ass’n v. City of Platteville, 179 F.3d 574 (7th Cir.1999). Because it is infeasible to quantify the benefits and costs of most law enforcement programs, the program approach might well permit deep inroads into privacy. In high-crime areas of America’s cities it might justify methods of policing that are associated with totalitarian nations. Cf. Brown v. Texas, 443 U.S. 47, 99 S.Ct. 2637, 61 L.Ed.2d 357 (1979). One can imagine an argument that it would be reasonable in a drug-infested neighborhood to administer drug tests randomly to drivers and pedestrians. Although there is nothing in the text of the Fourth Amendment to prevent dragnet searches (read literally, the text requires only that searches and seizures be “reasonable” and confines the requirement of “probable cause” to searches or seizures made pursuant to warrant), the Supreme Court has insisted that “to be reasonable under the Fourth Amendment, a search ordinarily must be based on individualized suspicion of wrongdoing,” save in cases of “special need” based on “concerns other than crime detection.” Chandler v. Miller, 520 U.S. 305, 313-14, 117 S.Ct. 1295, 137 L.Ed.2d 513 (1997) (emphasis added); see also Vernonia School District 47J v. Acton, 515 U.S. 646, 653, 115 S.Ct. 2386, 132 L.Ed.2d 564 (1995); United States v. Martinez-Fuerte, supra, 428 U.S. at 560-61, 96 S.Ct. 3074; Terry v. Ohio, 392 U.S. 1, 27, 88 S.Ct.
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POSNER, Chief Judge.
A class action has been brought to enjoin the City of Indianapolis from setting up roadblocks to catch drug offenders, a practice that the plaintiffs claim violates the Fourth Amendment. The plaintiffs’ motion for a preliminary injunction was denied on the ground that the City’s practice is lawful, precipitating this interlocutory appeal under 28 U.S.C. § 1292(a)(1). The legality of drug roadblocks has divided the other courts that have been asked to decide the issue. Compare United States v. Huguenin, 154 F.3d 547, 554-55 (6th Cir.1998); United States v. Morales-Zamora, 974 F.2d 149 (10th Cir.1992); Galberth v. United States, 590 A.2d 990 (D.C.1991), and Wilson v. Commonwealth, 29 Va.App. 63, 509 S.E.2d 540 (1999), which held them illegal, with Merrett v. Moore, 58 F.3d 1547 (11th Cir.1995), and State v. Damask, 936 S.W.2d 565 (Mo.1996), which held them legal. This is our first case. Because it was decided by the district court on a very skimpy stipulation of facts, our ruling on the legality of the City’s program is necessarily tentative.
Six times between August and November of last year, the City’s police department set up roadblocks on Indianapolis streets to catch drug offenders. A total of 1,161 cars were stopped at these roadblocks — for how long is unclear but the police endeavor to operate the checkpoints in such a manner that the stop does not exceed five minutes. During the stop, the police demand the driver’s license and car registration, peer through the car’s windows into its interior, and lead a drug-sniffing dog around the car. The stopping of the 1,161 vehicles resulted in 55 drug-related arrests, meaning that 5 percent of the total number of stops resulted in successful drug “hits,” and 49 arrests for conduct unrelated to drugs, such as ■ driving with an expired driver’s license, for .an overall hit rate of 9 percent. The City is continuing the program.
Stopping a car at a roadblock is a seizure within the meaning of the Fourth Amendment, Whren v. United States, 517 U.S. 806, 809-10, 116 S.Ct. 1769, 135 L.Ed.2d 89 (1996); Michigan Dept. of State Police v. Sitz, 496 U.S. 444, 450, 110 S.Ct. 2481, 110 L.Ed.2d 412 (1990), even though the sequel — the peering into the car windows and the sniffing of the car by the dog outside — does not rise to the level of a search as that term of the amendment has been interpreted by the Supreme Court. United States v. Place, 462 U.S. 696, 707, 103 S.Ct. 2637, 77 L.Ed.2d 110 (1983); Texas v. Brown, 460 U.S. 730, 739-40, 103 S.Ct. 1535, 75 L.Ed.2d 502 (1983); United States v. Ware, 914 F.2d 997, 1000 (7th Cir.1990); United States v. Rodriguez-Morales, 929 F.2d 780, 788-89 (1st Cir.1991). Whether the seizures effected by Indianapolis’s drug roadblocks are reasonable may depend on whether reasonableness is to be assessed at the level of the entire program or of the individual stop. If the former, these roadblocks probably are legal, given the high “hit” rate and the only modestly intrusive character of the stops. In many Fourth Amendment contexts, the reasonableness of a practice is held to depend on the balance between its benefits (usually non-pecuniary) and its costs (ditto). E.g., Wyoming v. Houghton, — U.S. -, -, 119 S.Ct. 1297, 1300, 143 L.Ed.2d 408 (1999); Whren v. United States, supra, 517 U.S. at 817, 116 S.Ct. 1769; Skinner v. Railway Labor Executives’ Ass’n, 489 U.S. 602, 619, 109 S.Ct. 1402, 103 L.Ed.2d 639 (1989); Camara v. Municipal Court, 387 U.S. 523, 536-37, 87 S.Ct. 1727, 18 L.Ed.2d 930 (1967); Dimeo v. Griffin, 943 F.2d 679, 681 (7th Cir.1991) (en banc). The benefits of a random system of searches or seizures, such as vehicle stops pursuant to a roadblock system, are a function of, first, the probability that the stop will result in [662]*662an arrest or a seizure of contraband or evidence of crime, and, second, the gain to the achievement of a lawful governmental goal that such an arrest or seizure will produce. The costs are a function of the harm that the stop will cause to the property or privacy of the people whose cars are stopped. In the case of Indianapolis’s drug-roadblock program, the probability of a “hit” is high .(vastly higher than, for example, the probability of a hit as a result of the screening of embarking passengers and their luggage at airports, see National Treasury Employees Union v. Von Raab, 489 U.S. 656, 675 n. 3, 109 S.Ct. 1384, 103 L.Ed.2d 685 (1989)), and the deterrence of drug offenses produced by these hits advances the strong national, state, and local policy of discouraging the illegal use of controlled substances. The cost — in delay, anxiety, and invasion of privacy — to the drivers and passengers stopped for five minutes at a roadblock and subjected to a visual inspection of the interior and a sniff by a dog is small, though it is greater than the cost of the normal airport screening and (like that screening) is incurred in all stops while the benefit from the program is obtained only when there is a hit.
But courts do not usually assess reasonableness at the program level when they are dealing with searches related to general criminal law enforcement, see, e.g., Whren v. United States, supra, 517 U.S. at 810, 116 S.Ct. 1769, rather than to primarily civil regulatory programs for the protection of health, safety, and the integrity of our borders. E.g., Michigan v. Tyler, 436 U.S. 499, 504-06, 98 S.Ct. 1942, 56 L.Ed.2d 486 (1978); United States v. Martinez-Fuerte, 428 U.S. 543, 96 S.Ct. 3074, 49 L.Ed.2d 1116 (1976); Camara v. Municipal Court, supra; Platteville Area Apartment Ass’n v. City of Platteville, 179 F.3d 574 (7th Cir.1999). Because it is infeasible to quantify the benefits and costs of most law enforcement programs, the program approach might well permit deep inroads into privacy. In high-crime areas of America’s cities it might justify methods of policing that are associated with totalitarian nations. Cf. Brown v. Texas, 443 U.S. 47, 99 S.Ct. 2637, 61 L.Ed.2d 357 (1979). One can imagine an argument that it would be reasonable in a drug-infested neighborhood to administer drug tests randomly to drivers and pedestrians. Although there is nothing in the text of the Fourth Amendment to prevent dragnet searches (read literally, the text requires only that searches and seizures be “reasonable” and confines the requirement of “probable cause” to searches or seizures made pursuant to warrant), the Supreme Court has insisted that “to be reasonable under the Fourth Amendment, a search ordinarily must be based on individualized suspicion of wrongdoing,” save in cases of “special need” based on “concerns other than crime detection.” Chandler v. Miller, 520 U.S. 305, 313-14, 117 S.Ct. 1295, 137 L.Ed.2d 513 (1997) (emphasis added); see also Vernonia School District 47J v. Acton, 515 U.S. 646, 653, 115 S.Ct. 2386, 132 L.Ed.2d 564 (1995); United States v. Martinez-Fuerte, supra, 428 U.S. at 560-61, 96 S.Ct. 3074; Terry v. Ohio, 392 U.S. 1, 27, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968). Program-level justifications for searches in support of specific regulatory programs do not carry over to general criminal law enforcement. See, e.g., Chandler v. Miller, supra, 520 U.S. at 313-14, 117 S.Ct. 1295; New York v. Burger, 482 U.S. 691, 716 n. 27, 107 S.Ct. 2636, 96 L.Ed.2d 601 (1987); Michigan v. Tyler, supra, 436 U.S. at 508, 98 S.Ct. 1942; Donovan v. Dewey, 452 U.S. 594, 598 n. 6, 101 S.Ct. 2534, 69 L.Ed.2d 262 (1981); Abel v. United States, 362 U.S. 217, 226, 80 S.Ct. 683, 4 L.Ed.2d 668 (1960); Michigan v. Clifford, 464 U.S. 287, 294, 104 S.Ct. 641, 78 L.Ed.2d 477 (1984) (plurality opinion); United States v. $124,570 U.S. Currency, 873 F.2d 1240, 1244 (9th Cir.1989).
The qualification in “ordinarily” must not be overlooked. When the police establish a roadblock on a route that they know or strongly suspect is being used by a dangerous criminal to escape, the probability is high not only of apprehending the [663]*663criminal but also of preventing him from engaging in further criminal, or otherwise hazardous, activity incidental to his escape. See, e.g., United States v. Harper, 617 F.2d 35, 40-41 (4th Cir.1980). So the roadblock is allowed even though it is likely to “seize” some individuals who are not suspected of wrongdoing.
But here the roadblock is meant to intercept a completely random sample of drivers; there is neither probable cause nor articulable suspicion to stop any given driver. Even so, we can imagine cases in which, although the police do not suspect anyone, a roadblock or other dragnet method of criminal law enforcement would be reasonable. We may assume that if the Indianapolis police had a credible tip that a car loaded with dynamite and driven by an unidentified terrorist was en route to downtown Indianapolis, they would not be violating the Constitution if they blocked all the roads to the downtown area even though this would amount to stopping thousands of drivers without suspecting any one of them of criminal activity. See Maxwell v. City of New York, 102 F.3d 664 (2d Cir.1996); Norwood v. Bain, 143. F.3d 843, 845-50 (4th Cir.1998), aff'd. (so far as pertinent), 166 F.3d 243, 245 (4th Cir.1999) (en banc) (per curiam); United States v. Williams, 372 F.Supp. 65 (D.S.D.1974); Brinegar v. United States, 338 U.S. 160, 183, 69 S.Ct. 1302, 93 L.Ed. 1879 (1949) (Jackson, J., dissenting); 4 Wayne R. LaFave, Search and Seizure: A Treatise on the Fourth Amendment § 9.6(a) (3d ed.1996); American Law Institute, A Model Code of Pre-Arraignment Procedure § 110.2(2) (1975). When urgent considerations of the public safety require compromise with the normal principles constraining law enforcement, the normal principles may have to bend. The Constitution is not a suicide pact. But no such urgency has been shown here.
The Supreme Court has upheld the validity of roadblocks in less extreme cases, however, and it is on these that the City pitches its defense of its program. The Court upheld sobriéty checkpoints— roadblocks- at which drivers are checked for being under the influence of alcohol or (other) mind-altering drugs — in Michigan Dept. of State Police v. Sitz, 496 U.S. 444, 110 S.Ct. 2481, 110 L.Ed.2d 412 (1990), and roadblocks designed to intercept illegal immigrants, in United States v. Martinez-Fuerte, supra. The Court has not, however, ever held or stated that all roadblock programs (even those not vulnerable to a charge of delegating too much discretion to individual police officers) are consistent with the Fourth Amendment. On the contrary, the amendment would be violated if “the roadblock was a pretext whereby evidence of narcotics violation might be uncovered in ‘plain view’ in the course of a check for driver’s licenses.” Texas v. Brown, supra, 460 U.S. at 743, 103 S.Ct. 1535 (plurality opinion); see also United States v. Ortiz, 422 U.S. 891, 95 S.Ct. 2585, 45 L.Ed.2d 623 (1975).
Randomized search programs have been upheld that involved the compelled provision of urine samples for drug testing of law enforcement officers, jockeys, railroad workers, and other classes of employee, e.g., Vernonia School District 47J v. Acton, supra; National Treasury Employees Union v. Von Raab, supra, 489 U.S. at 665-66, 109 S.Ct. 1384; Skinner v. Railway Labor Executives’ Ass’n, supra; Dimeo v. Griffin, supra, as well as administrative searches conducted without any basis to suspect any particular individual of wrongdoing, but rather pursuant to a program of inspections incidental to a general scheme of licensing or other regulation. E.g., New York v. Burger, supra; Michigan v. Tyler, supra; Camara v. Municipal Court, supra; In re Establishment Inspection of Skil Corp., 846 F.2d 1127 (7th Cir.1988). But again the Court has not granted carte blanche.
Many of the cases we have cited do involve criminal prosecutions, however, and we must consider how they -can -be squared with the principle that the requirement of individualized suspicion is to [664]*664be relaxed only on the basis of (as the Supreme Court said in the Chandler case, an example of a systematic search program that did not pass constitutional muster) “concerns other than crime detection.” The answer is that the concern which lies behind the randomized or comprehensive systems of inspections or searches that have survived challenge under the Fourth Amendment is not primarily with catching crooks, but rather with securing the safety or efficiency of the activity in which the people who are searched are engaged. Consider employment drug tests for transport workers, as in the Skinner case. The employee who uses drugs will perform badly in his work, to the detriment of fellow employees or the general public; and the most effective preventive measure may be to test all or a random selection of applicants or employees. Similar are sobriety checkpoints, which are designed to protect other users of the road from the dangers posed by drunk drivers; administrative searches that are ancillary to con-cededly lawful systems of inspection; and the use of metal detectors and x-ray machines to screen entrants to government buildings and embarking air travelers. United States v. Herzbrun, 723 F.2d 773, 775-76 (11th Cir.1984); United States v. Edwards, 498 F.2d 496 (2d Cir.1974) (Friendly, J.); United States v. Davis, 482 F.2d 893, 908-10 (9th Cir.1973). These cases rest on the commonsense principle that employers and other proprietors (such as the state as the owner of public roads), including the quasi-proprietor that is the government in heavily regulated industries, see, e.g., United States v. Biswell, 406 U.S. 311, 316-17, 92 S.Ct. 1593, 32 L.Ed.2d 87 (1972), have a right to take reasonable measures to protect the safety and efficiency of their operations. These measures, moreover, usually make only limited inroads into privacy, because a person can avoid being searched or seized by avoiding the regulated activity, though we hesitate to put much weight on this point; people are unlikely to feel they can afford to “ground” themselves in order to avoid airport searches.
Indianapolis does not claim to be concerned with protecting highway safety against drivers high on drugs. Its program of drug roadblocks belongs to the genre of general programs of surveillance which invade privacy wholesale in order to discover evidence of crime. Imagine if the government set up a metal detector outside each person’s home and required the person to step through it whenever he entered or left, in order to determine whether he was carrying a gun for which he lacked a permit. A principle that justified a drug roadblock would justify such surveillance.
We mentioned cases that allow the police or the Border Patrol to set up roadblocks to intercept illegal immigrants, a form of “contraband” to which illegal drugs might be analogized. Other cases allow custom searches of the luggage of people entering the United States. For examples of both types of case, see United States v. Montoya de Hernandez, 473 U.S. 531, 537, 105 S.Ct. 3304, 87 L.Ed.2d 381 (1985); United States v. Martinez-Fuerte, supra; United States v. Ramsey, 431 U.S. 606, 616-19, 97 S.Ct. 1972, 52 L.Ed.2d 617 (1977); United States v. Johnson, 991 F.2d 1287, 1290-92 (7th Cir.1993). But such cases depend ultimately on sovereign powers over foreign relations, foreign commerce, citizenship, and immigration (see, e.g., Harisiades v. Shaughnessy, 342 U.S. 580, 586-89, 72 S.Ct. 512, 96 L.Ed. 586 (1952) (Jackson, J.)) that states and cities do not possess. Martinez-Fuerte involved searches well inland from the border, but the Court emphasized the infeasibility of preventing illegal immigration by border checks alone. 428 U.S. at 552, 96 S.Ct. 3074.
We are mindful of the paradoxical implication that the Fourth Amendment, though originally limited to federal law enforcement, may pinch the states more tightly. But the paradox need not detain us. Indianapolis makes no attempt to de[665]*665fend its roadblocks on the basis that it is trying to exclude a harmful substance or dangerous persons. Though that may be the ultimate aim, the City concedes that its proximate goal is to catch drug offenders in the hope of incapacitating them, and deterring others, by criminal prosecution. The program has no regulatory purpose that might be compared to that of the immigration laws, which seek to exclude and deport illegal immigrants rather than just to prosecute them for criminal violations of the immigration laws.
It is true that in the course of looking for drugs in vehicles stopped at its drug roadblocks, the Indianapolis police often discover violations of the traffic laws. If the purpose of the roadblock program were to discover such violations, and if a program having such a purpose could be justified under the cases that allow searches and seizures without individualized suspicion of wrongdoing, then the seizure, in the course of such searches, of drugs that were in plain view would be lawful. Texas v. Brown, supra; United States v. Trevino, 60 F.3d 333, 336 (7th Cir.1995). But the first “if’ has not been shown. It is necessary in this regard to distinguish between two kinds of purpose, that of the program’s designers and that of the police officers manning the roadblocks. The test for the lawfulness of a particular search or seizure is an objective one; the motives of the officer carrying out the search or seizure are irrelevant. Whren v. United States, supra, 517 U.S. at 811-13, 116 S.Ct. 1769; United States v. VillamonteMarquez, 462 U.S. 579, 584 n. 3, 103 S.Ct. 2573, 77 L.Ed.2d 22 (1983); Scott v. United States, 436 U.S. 128, 138, 98 S.Ct. 1717, 56 L.Ed.2d 168 (1978); cf. Graham v. Connor, 490 U.S. 386, 397, 109 S.Ct. 1865, 104 L.Ed.2d 443 (1989). But the purpose behind the program is critical to its legality. The program must be a bona fide effort ,to implement an authorized regulatory policy rather than a pretext for a dragnet search for criminals. New York v. Burger, supra, 482 U.S. at 716 n. 27, 107 S.Ct. 2636. “[T]he exemption from the need for probable cause (and warrant), which is accorded to searches made for the purpose of inventory or administrative regulation, is not apcorded to searches that are not made for those purposes.” Whren v. United States, supra, 517 U.S. at 811-12, 116 S.Ct. 1769 (emphasis in original); see also Texas v. Brown, supra, 460 U.S. at 743, 103 S.Ct. 1535 (plurality opinion). Leading a drug-sniffing dog around a car cannot be justified by reference to a desire to detect traffic violations, and so the use of the dog at the City’s roadblocks shows — what is anyway not contested— that the purpose of the roadblocks is to catch drug offenders. We are not asked to decide whether, if the primary purpose were to detect drunken drivers, the dog could be added to the roadblock scenario on the theory that since a sniff is not a search, the incremental invasion of privacy would be negligible, or at least would not violate the Fourth Amendment.
It can be objected that requiring consideration of purpose injects too large an element of uncertainty into the interpretation of the amendment, and that purpose may be difficult to determine when it is corporate in nature. But law like politics is the art of the possible and often requires imperfect compromises. Inquiry into purpose is one method of identifying and banning the most flagrantly abusive governmental conduct without handcuffing government altogether. The alternative would be to rule that either all roadblocks are illegal or none are, which would be akin to punishing all killings identically because the “objective” fact is that someone has died.
To summarize, we have identified four exceptions to the principle that a search or seizure is forbidden by the Fourth Amendment unless there is a basis for believing that a particular search or seizure, as distinct from a program of universal or randomized searches or seizures, will yield evidence or fruits or instrumentalities of crime. The first exception, illus[666]*666trated by the roadblock set up to catch a fleeing criminal, is where there is a suspect — the police have identified the criminal and have only to find him- — but it is infeasible to avoid an indiscriminate search or seizure of other persons, persons not suspected of crime, as well. The second exception, illustrated by the hypothetical dynamite ease, is where no specific person is under suspicion but the circumstances make it impossible to prevent a crime without an indiscriminate search. The third exception is the regulatory search, the objective of which is to protect a specific activity rather than to operate as an adjunct to general criminal law enforcement. The last exception is the prevention of illegal importation whether of persons (a power limited to the federal government, Saenz v. Roe, - U.S. -, 119 S.Ct. 1518, 143 L.Ed.2d 689 (1999)) or of goods. On the basis of the record compiled in the preliminary-injunction proceedings — a record essentially limited to the parties’ stipulation of facts — the Indianapolis roadblock program has not been shown to fit any of these exceptions, and thus the lawfulness of the program has not, as the district judge believed, been established. As that was the only ground on which she denied the preliminary injunction, her order cannot stand.
Whether there may be other grounds for denying the preliminary injunction, or whether on a fuller record the Indianapolis program might pass Fourth Amendment muster, are issues for the district court to decide in the first instance. We are not enthusiastic about the use of the Constitution to squelch experiments in dealing with serious social problems. The high hit rate of Indianapolis’s roadblock scheme suggests that Indianapolis has placed the roadblocks in areas of the city in which drug use approaches epidemic proportions; and if so the roadblocks might be justified by reference to the second exception, as illustrated by such cases as Maxwell (involving a flurry of drive-by shootings), Norwood (threat of violence at a rally of motorcycle gangs), and Williams (Indian insurrection). But this is not argued either.
REVERSED.