JUSTICE REHNQUIST delivered the opinion of the Court.
Respondent Rosa Elvira Montoya de Hernandez was detained by customs officials upon her arrival at the Los Angeles Airport on a flight from Bogota, Colombia. She was found to be smuggling 88 cocaine-filled balloons in her alimentary
Respondent arrived at Los Angeles International Airport shortly after midnight, March 5, 1983, on Avianca Flight 080, a direct 10-hour flight from Bogota, Colombia. Her visa was in order so she was passed through Immigration and proceeded to the customs desk. At the customs desk she encountered Customs Inspector Talamantes, who reviewed her documents and noticed from her passport that she had made at least eight recent trips to either Miami or Los Angeles. Talamantes referred respondent to a secondary customs desk for further questioning. At this desk Talamantes and another inspector asked respondent general questions concerning herself and the purpose of her trip. Respondent revealed that she spoke no English and had no family or friends in the United States. She explained in Spanish that she had come to the United States to purchase goods for her husband's store in Bogota. The customs inspectors recognized Bogota as a "source city" for narcotics. Respondent possessed $5,000 in cash, mostly $50 bills, but had no billfold. She indicated to the inspectors that she had no appointments with merchandise vendors, but planned to ride around Los Angeles in taxicabs visiting retail stores such as J. C. Penney and K-Mart in order to buy goods for her husband's store with the $5,000.
Respondent admitted that she had no hotel reservations, but stated that she planned to stay at a Holiday Inn. Respondent could not recall how her airline ticket was purchased.
At this point Talamantes and the other inspector suspected that respondent was a "balloon swallower," one who attempts to smuggle narcotics into this country hidden in her alimentary canal. Over the years Inspector Talamantes had apprehended dozens of alimentary canal smugglers arriving on Avianca Flight 080. See App. 42; United States v. Mendez-Jimenez, 709 F.2d 1300, 1301 (CA9 1983).
The inspectors requested a female customs inspector to take respondent to a private area and conduct a patdown and strip search. During the search the female inspector felt respondent's abdomen area and noticed a firm fullness, as if respondent were wearing a girdle. The search revealed no contraband, but the inspector noticed that respondent was wearing two pairs of elastic underpants with a paper towel lining the crotch area.
When respondent returned to the customs area and the female inspector reported her discoveries, the inspector in charge told respondent that he suspected she was smuggling drugs in her alimentary canal. Respondent agreed to the inspector's request that she be x-rayed at a hospital but in answer to the inspector's query stated that she was pregnant. She agreed to a pregnancy test before the x ray. Respondent withdrew the consent for an x ray when she learned that she would have to be handcuffed en route to the hospital. The inspector then gave respondent the option of returning to Colombia on the next available flight, agreeing to an x ray, or remaining in detention until she produced a monitored bowel movement that would confirm or rebut the inspectors'
Respondent sat in the customs office, under observation, for the remainder of the night. During the night customs officials attempted to place respondent on a Mexican airline that was flying to Bogota via Mexico City in the morning. The airline refused to transport respondent because she lacked a Mexican visa necessary to land in Mexico City. Respondent was not permitted to leave, and was informed that she would be detained until she agreed to an x ray or her bowels moved. She remained detained in the customs office under observation, for most of the time curled up in a chair leaning to one side. She refused all offers of food and drink, and refused to use the toilet facilities. The Court of Appeals noted that she exhibited symptoms of discomfort consistent with "heroic efforts to resist the usual calls of nature." 731 F. 2d, at 1371.
At the shift change at 4:00 o'clock the next afternoon, almost 16 hours after her flight had landed, respondent still had not defecated or urinated or partaken of food or drink. At that time customs officials sought a court order authorizing a pregnancy test, an x ray, and a rectal examination. The Federal Magistrate issued an order just before midnight that evening, which authorized a rectal examination and involuntary x ray, provided that the physician in charge considered respondent's claim of pregnancy. Respondent was taken to a hospital and given a pregnancy test, which later turned out to be negative. Before the results of the pregnancy test were known, a physician conducted a rectal examination and removed from respondent's rectum a balloon containing a foreign substance. Respondent was then placed
After a suppression hearing the District Court admitted the cocaine in evidence against respondent. She was convicted of possession of cocaine with intent to distribute, 21 U. S. C. § 841(a)(1), and unlawful importation of cocaine, 21 U. S. C. §§ 952(a), 960(a).
A divided panel of the United States Court of Appeals for the Ninth Circuit reversed respondent's convictions. The court noted that customs inspectors had a "justifiably high level of official skepticism" about respondent's good motives, but the inspectors decided to let nature take its course rather than seek an immediate magistrate's warrant for an x ray. 731 F. 2d, at 1372. Such a magistrate's warrant required a "clear indication" or "plain suggestion" that the traveler was an alimentary canal smuggler under previous decisions of the Court of Appeals. See United States v. Quintero-Castro, 705 F.2d 1099 (CA9 1983); United States v. Mendez-Jimenez, 709 F.2d 1300, 1302 (CA9 1983); but cf. South Dakota v. Opperman, 428 U.S. 364, 370, n. 5 (1976). The court applied this required level of suspicion to respondent's case. The court questioned the "humanity" of the inspectors' decision to hold respondent until her bowels moved, knowing that she would suffer "many hours of humiliating discomfort" if she chose not to submit to the x-ray examination. The court concluded that under a "clear indication" standard "the evidence available to the customs officers when they decided to hold [respondent] for continued observation was insufficient to support the 16-hour detention." 731 F. 2d, at 1373.
The Government contends that the customs inspectors reasonably suspected that respondent was an alimentary canal smuggler, and this suspicion was sufficient to justify the detention. In support of the judgment below respondent
The Fourth Amendment commands that searches and seizures be reasonable. What is reasonable depends upon all of the circumstances surrounding the search or seizure and the nature of the search or seizure itself. New Jersey v. T. L. O., 469 U.S. 325, 337-342 (1985). The permissibility of a particular law enforcement practice is judged by "balancing its intrusion on the individual's Fourth Amendment interests against its promotion of legitimate governmental interests." United States v. Villamonte-Marquez, 462 U.S. 579, 588 (1983); Delaware v. Prouse, 440 U.S. 648, 654 (1979); Camara v. Municipal Court, 387 U.S. 523 (1967).
Here the seizure of respondent took place at the international border. Since the founding of our Republic, Congress has granted the Executive plenary authority to conduct routine searches and seizures at the border, without probable cause or a warrant, in order to regulate the collection of duties and to prevent the introduction of contraband into this country. See United States v. Ramsey, 431 U.S. 606, 616-617 (1977), citing Act of July 31, 1789, ch. 5, 1 Stat. 29. This Court has long recognized Congress' power to police entrants at the border. See Boyd v. United States, 116 U.S. 616, 623 (1886). As we stated recently:
Consistently, therefore, with Congress' power to protect the Nation by stopping and examining persons entering this country, the Fourth Amendment's balance of reasonableness is qualitatively different at the international border than in the interior. Routine searches of the persons and effects of entrants are not subject to any requirement of reasonable suspicion, probable cause, or warrant,
These cases reflect longstanding concern for the protection of the integrity of the border. This concern is, if anything, heightened by the veritable national crisis in law enforcement caused by smuggling of illicit narcotics, see United States v. Mendenhall, 446 U.S. 544, 561 (1980) (POWELL, J., concurring), and in particular by the increasing utilization of alimentary canal smuggling. This desperate practice appears to be a relatively recent addition to the smugglers' repertoire of deceptive practices, and it also appears to be exceedingly difficult
Balanced against the sovereign's interests at the border are the Fourth Amendment rights of respondent. Having presented herself at the border for admission, and having subjected herself to the criminal enforcement powers of the Federal Government, 19 U. S. C. § 482, respondent was entitled to be free from unreasonable search and seizure. But not only is the expectation of privacy less at the border than in the interior, see e. g., Carroll v. United States, 267 U.S. 132,
We have not previously decided what level of suspicion would justify a seizure of an incoming traveler for purposes other than a routine border search. Cf. Ramsey, 431 U. S., at 618, n. 13. The Court of Appeals held that the initial detention of respondent was permissible only if the inspectors possessed a "clear indication" of alimentary canal smuggling. 731 F. 2d, at 1372, citing United States v. Quintero-Castro, 705 F.2d 1099 (CA9 1983); cf. United States v. Mendez-Jimenez, 709 F.2d 1300 (CA9 1983). This "clear indication" language comes from our opinion in Schmerber v. California, 384 U.S. 757 (1966), but we think that the Court of Appeals misapprehended the significance of that phrase in the context in which it was used in Schmerber.
No other court, including this one, has ever adopted Schmerber's "clear indication" language as a Fourth Amendment standard. See, e. g., Winston v. Lee, 470 U.S. 753,
We hold that the detention of a traveler at the border, beyond the scope of a routine customs search and inspection, is justified at its inception if customs agents, considering all the facts surrounding the traveler and her trip, reasonably suspect that the traveler is smuggling contraband in her alimentary canal.
The "reasonable suspicion" standard has been applied in a number of contexts and effects a needed balance between private and public interests when law enforcement officials must make a limited intrusion on less than probable cause. It thus fits well into the situations involving alimentary canal smuggling at the border: this type of smuggling gives no external signs and inspectors will rarely possess probable cause to arrest or search, yet governmental interests in stopping smuggling at the border are high indeed. Under this standard officials at the border must have a "particularized and objective basis for suspecting the particular person" of alimentary
The facts, and their rational inferences, known to customs inspectors in this case clearly supported a reasonable suspicion that respondent was an alimentary canal smuggler. We need not belabor the facts, including respondent's implausible story, that supported this suspicion, see supra, at 533-536. The trained customs inspectors had encountered many alimentary canal smugglers and certainly had more than an "inchoate and unparticularized suspicion or `hunch,' " Terry, supra, at 27, that respondent was smuggling narcotics in her alimentary canal. The inspectors' suspicion was a " `common-sense conclusio[n] about human behavior' upon which `practical people,' — including government officials, are entitled to rely." T. L. O., 469 U. S., at 346, citing United States v. Cortez, supra.
The final issue in this case is whether the detention of respondent was reasonably related in scope to the circumstances which justified it initially. In this regard we have cautioned that courts should not indulge in "unrealistic second-guessing," United States v. Sharpe, 470 U.S. 675, 686 (1985), and we have noted that "creative judge[s], engaged in post hoc evaluations of police conduct can almost always imagine some alternative means by which the objectives of the police might have been accomplished." Id., at 686-687. But "[t]he fact that the protection of the public might, in the abstract, have been accomplished by `less intrusive' means does not, in itself, render the search unreasonable." Id., at 687, citing Cady v. Dombrowski, 413 U.S. 433, 447 (1973). Authorities must be allowed "to graduate their response to the demands of any particular situation." United States v. Place, 462 U.S. 696, 709, n. 10 (1983). Here, respondent was detained incommunicado for almost 16 hours before inspectors sought a warrant; the warrant then took a number of hours to procure, through no apparent fault
The rudimentary knowledge of the human body which judges possess in common with the rest of humankind tells us that alimentary canal smuggling cannot be detected in the amount of time in which other illegal activity may be investigated through brief Terry-type stops. It presents few, if any external signs; a quick frisk will not do, nor will even a strip search. In the case of respondent the inspectors had available, as an alternative to simply awaiting her bowel movement, an x ray. They offered her the alternative of submitting herself to that procedure. But when she refused that alternative, the customs inspectors were left with only two practical alternatives: detain her for such time as necessary to confirm their suspicions, a detention which would last much longer than the typical Terry stop, or turn her loose into the interior carrying the reasonably suspected contraband drugs.
The inspectors in this case followed this former procedure. They no doubt expected that respondent, having recently disembarked from a 10-hour direct flight with a full and stiff abdomen, would produce a bowel movement without extended delay. But her visible efforts to resist the call of nature, which the court below labeled "heroic," disappointed this expectation and in turn caused her humiliation and discomfort. Our prior cases have refused to charge police with delays in investigatory detention attributable to the suspect's evasive actions, see Sharpe, 470 U. S., at 687-688; id., at 697 (MARSHALL, J., concurring in judgment), and that principle applies here as well. Respondent alone was responsible for much of the duration and discomfort of the seizure.
Respondent's detention was long, uncomfortable, indeed, humiliating; but both its length and its discomfort resulted solely from the method by which she chose to smuggle illicit drugs into this country. In Adams v. Williams, 407 U.S. 143 (1972), another Terry-stop case, we said that "[t]he Fourth Amendment does not require a policeman who lacks the precise level of information necessary for probable cause to arrest to simply shrug his shoulders and allow a crime to occur or a criminal to escape." Id., at 145. Here, by analogy, in the presence of articulable suspicion of smuggling in her alimentary canal, the customs officers were not required by the Fourth Amendment to pass respondent and her 88 cocaine-filled balloons into the interior. Her detention for the period of time necessary to either verify or dispel the suspicion was not unreasonable. The judgment of the Court of Appeals is therefore
If a seizure and a search of the person of the kind disclosed by this record may be made on the basis of reasonable suspicion, we must assume that a significant number of innocent persons will be required to undergo similar procedures. The rule announced in this case cannot, therefore, be supported on the ground that respondent's prolonged and humiliating detention "resulted solely from the method by which she chose to smuggle illicit drugs into this country." Ante, at 544.
The prolonged detention of respondent was, however, justified by a different choice that respondent made; she withdrew her consent to an x-ray examination that would have easily determined whether the reasonable suspicion that she was concealing contraband was justified. I believe that customs agents may require that a nonpregnant person reasonably suspected of this kind of smuggling submit to an x-ray examination as an incident to a border search. I therefore concur in the judgment.
JUSTICE BRENNAN, with whom JUSTICE MARSHALL joins, dissenting.
We confront a "disgusting and saddening episode" at our Nation's border.
Stymied in their efforts, the officers decided on an alternative course: they would simply lock De Hernandez away in an adjacent manifest room "until her peristaltic functions produced a monitored bowel movement."
De Hernandez remained locked up in the room for almost 24 hours. Three shifts of matrons came and went during this time. The room had no bed or couch on which she could lie, but only hard chairs and a table. The matrons told her that if she wished to sleep she could lie down on the hard, uncarpeted floor. De Hernandez instead "sat in her chair clutching her purse," "occasionally putting her head down on the table to nap."
After almost 24 hours had passed, someone finally had the presence of mind to consult a Magistrate and to obtain a court order for an x ray and a body-cavity search.
"[T]hat the [respondent] so degraded herself as to offend the sensibilities of any decent citizen is not questioned."
The issue, instead, is simply this: Does the Fourth Amendment permit an international traveler, citizen or alien, to be subjected to the sort of treatment that occurred in this case without the sanction of a judicial officer and based on nothing more than the "reasonable suspicion" of low-ranking investigative officers that something might be amiss? The Court today concludes that the Fourth Amendment grants such sweeping and unmonitored authority to customs officials. It reasons that "[t]he permissibility of a particular law enforcement practice is judged by `balancing its intrusion on the individual's Fourth Amendment interests against its promotion of legitimate governmental interests.' " Ante, at 537. The Court goes on to assert that the "balance of reasonableness is qualitatively different at the international border," and that searches and seizures in these circumstances may therefore be conducted without probable cause or a warrant. Ante, at 538. Thus a traveler at the Nation's border may be detained for criminal investigation merely if the authorities "reasonably suspect that the traveler is smuggling contraband." Ante, at 541. There are no "hard-and-fast time limits" for
JUSTICE STEVENS takes a somewhat different tack. Apparently convinced that the health effects of x-irradiation on human beings stand established as so minimal as to be little cause for concern, he believes that low-ranking customs officials on their own initiative may require nonpregnant international travelers to submit to warrantless x rays on nothing more than suspicion if such travelers wish to avoid indeterminate warrantless detentions. Because De Hernandez withdrew her consent to proceed in handcuffs to such an examination, "[t]he prolonged detention of respondent was. . . justified." Ante, at 545 (concurring in judgment).
I dissent. Indefinite involuntary incommunicado detentions "for investigation" are the hallmark of a police state, not a free society. See, e. g., Dunaway v. New York, 442 U.S. 200 (1979); Brown v. Illinois, 422 U.S. 590 (1975); Davis v. Mississippi, 394 U.S. 721 (1969). In my opinion, Government officials may no more confine a person at the border under such circumstances for purposes of criminal investigation than they may within the interior of the country. The nature and duration of the detention here may well have been tolerable for spoiled meat or diseased animals, but not for human beings held on simple suspicion of criminal activity. I believe such indefinite detentions can be "reasonable" under the Fourth Amendment only with the approval of a magistrate. I also believe that such approval can be given only upon a showing of probable cause. Finally, I believe that the warrant and probable-cause safeguards equally govern JUSTICE STEVENS' proffered alternative of exposure to x-irradiation for criminal-investigative purposes.
Travelers at the national border are routinely subjected to questioning, patdowns, and thorough searches of their belongings. These measures, which involve relatively limited invasions of privacy and which typically are conducted on all incoming travelers, do not violate the Fourth Amendment given the interests of "national self protection reasonably requiring one entering the country to identify himself as entitled to come in, and his belongings as effects which may be lawfully brought in." Carroll v. United States, 267 U.S. 132, 154 (1925).
Accordingly, the Court repeatedly has emphasized that the Fourth Amendment's Warrant Clause is not mere "dead language" or a bothersome "inconvenience to be somehow `weighed' against the claims of police efficiency. It is, or should be, an important working part of our machinery of government, operating as a matter of course to check the `well-intentioned but mistakenly overzealous executive officers' who are a part of any system of law enforcement." United States v. United States District Court, supra, at 315; Coolidge v. New Hampshire, 403 U.S. 443, 473-484 (1971).
The Government contends, however, that because investigative detentions of the sort that occurred in this case need not be supported by probable cause, no warrant is required, given the phraseology of the Fourth Amendment's Warrant
Something has gone fundamentally awry in our constitutional jurisprudence when a neutral and detached magistrate's authorization is required before the authorities may inspect "the plumbing, heating, ventilation, gas, and electrical
The Court supports its evasion of the warrant requirement, however, by analogizing to the Terry line of cases authorizing brief detentions based on reasonable suspicion. It argues that no "hard-and-fast time limits" can apply in this context because "alimentary canal smuggling cannot be detected in the amount of time in which other illegal activity may be investigated through brief Terry-type stops." Ante, at 543. I have previously set forth my views on the proper scope and duration of Terry stops,
The Court argues, however, that the length and "discomfort" of De Hernandez' detention "resulted solely from the method by which she chose to smuggle illicit drugs into this country," and it speculates that only her " `heroic' " efforts prevented the detention from being brief and to the point. Ante, at 544 (emphasis added). Although we now know that De Hernandez was indeed guilty of smuggling drugs internally, such post hoc rationalizations have no place in our Fourth Amendment jurisprudence, which demands that we "prevent hindsight from coloring the evaluation of the reasonableness of a search or seizure." United States v. Martinez-Fuerte, 428 U. S., at 565. See also Beck v. Ohio, 379 U.S. 89, 96 (1964). At the time the authorities simply had, at most, a reasonable suspicion that De Hernandez
The Court further appears to believe that such investigative practices are "reasonable," however, on the premise that a traveler's "expectation of privacy [is] less at the border than in the interior." Ante, at 539. This may well be so with respect to routine border inspections, but I do not imagine that decent and law-abiding international travelers have yet reached the point where they "expect" to be thrown into locked rooms and ordered to excrete into wastebaskets, held incommunicado until they cooperate, or led away in handcuffs to the nearest hospital for exposure to various medical procedures — all on nothing more than the "reasonable" suspicions of low-ranking enforcement agents. In fact, many people from around the world travel to our borders precisely to escape such unchecked executive investigatory discretion. What a curious first lesson in American liberty awaits them
Finally, I disagree with JUSTICE STEVENS that De Hernandez' alternative "choice" of submitting to abdominal x-irradiation at the discretion of customs officials made this detention "justified." Ante, at 545 (concurring in judgment). Medical x rays are of course a common diagnostic technique; that is exactly why there is such a sharp debate among the medical community concerning the cellular and chromosomal effects of routine reliance on x rays, both from the perspective of individual health (it having been estimated that a routine medical x ray takes about six days off a person's life expectancy
I believe that De Hernandez' detention violated the Fourth Amendment for an additional reason: it was not supported by probable cause. In the domestic context, a detention of the sort that occurred here would be permissible only if there were probable cause at the outset. See, e. g., Hayes v. Florida, 470 U.S. 811, 815 (1985); Dunaway v. New York, 442 U. S., at 207-208, 212-216; Brown v. Illinois, 422 U. S., at 602, 605; Davis v. Mississippi, 394 U. S., at 726-727. This
To be sure, it is commonly asserted that as a result of the Fourth Amendment's "border exception" there is no requirement of probable cause for such investigations.
Contrary to the Court's reasoning, however, the Government in carrying out such immigration and customs functions does not simply have the two stark alternatives of either forcing
This does not, of course, mean that such individuals are not fully subject to the criminal laws while on American soil. If there is probable cause to believe they have violated the law, they may be arrested just like any other person within our borders. And if there is "reasonable suspicion" to believe they may be engaged in such violations, they may briefly be detained pursuant to Terry for further investigation, subject to the same limitations and conditions governing Terry stops anywhere else in the country.
The Government disagrees. We were advised at oral argument that it "definitely" is the policy of customs authorities "not to allow such people, if they're reasonably suspected of drug smuggling, to return before that suspicion can be checked out" and that, whether citizen, resident alien, or alien, "[w]e would not simply let them go back." Tr. of Oral Arg. 5, 48. The result is to sanction an authoritarian twilight zone on the border. The suspicious-looking traveler may not enter the country. Nor may he leave. Instead, he
Nothing in the underlying premises of the "border exception" supports such a ring of unbridled authoritarianism surrounding freedom's soil. If the traveler does not wish to consent to prolonged detentions or intrusive examinations, the Nation's customs and immigration interests are fully served by sending the traveler on his way elsewhere. If the authorities nevertheless propose to detain the traveler for purposes of subjecting him to criminal investigation and possible arrest and punishment, they may do so only pursuant to constitutional safeguards applicable to everyone else in the country. See Wong Wing v. United States, 163 U. S., at 236-238; Abel v. United States, 362 U. S., at 250 (BRENNAN, J., dissenting).
In my opinion, allowing the Government to hold someone in indefinite, involuntary, incommunicado isolation without
"Travellers may be so stopped in crossing an international boundary because of national self protection reasonably requiring one entering the country to identify himself as entitled to come in and his belongings as effects which may be lawfully brought in."
"The interests in human dignity and privacy which the Fourth Amendment protects forbid any such intrusion [beyond the body's surface] on the mere chance that desired evidence might be obtained. In the absence of a clear indication that in fact such evidence will be found, these fundamental human interests require law officers to suffer the risk that such evidence may disappear unless there is an immediate search." 384 U. S., at 769-770.
The Magistrate's order was based largely on the observations by customs officials of De Hernandez' behavior during her detention. See App. 42. As the Ninth Circuit concluded, because the unlawful detention produced the "additional evidence" that was used to obtain the order, the contraband discovered in implementing the order was tainted and therefore improperly introduced at De Hernandez' trial. 731 F. 2d, at 1372.
"We must remember that the extent of any privilege of search and seizure without warrant which we sustain, the officers interpret and apply themselves and will push to the limit. We must remember, too, that freedom from unreasonable search differs from some of the other rights of the Constitution in that there is no way in which the innocent citizen can invoke advance protection. For example, any effective interference with freedom of the press, or free speech, or religion, usually requires a course of suppressions against which the citizen can and often does go to the court and obtain an injunction. Other rights, such as that to an impartial jury or the aid of counsel, are within the supervisory power of the courts themselves. Such a right as just compensation for the taking of private property may be vindicated after the act in terms of money.
"But an illegal search and seizure usually is a single incident, perpetrated by surprise, conducted in haste, kept purposely beyond the court's supervision and limited only by the judgment and moderation of officers whose own interests and records are often at stake in the search. There is no opportunity for injunction or appeal to disinterested intervention. The citizen's choice is quietly to submit to whatever the officers undertake or to resist at risk of arrest or immediate violence." 338 U. S., at 182 (dissenting opinion).
"To require a showing of some extraordinary governmental interest before dispensing with the warrant requirement is not to undervalue society's need to apprehend violators of the criminal law. To be sure, forcing law enforcement personnel to obtain a warrant before engaging in a search will predictably deter the police from conducting some searches that they would otherwise like to conduct. But this is not an unintended result of the Fourth Amendment's protection of privacy; rather, it is the very purpose for which the Amendment was thought necessary. Only where the governmental interests at stake exceed those implicated in any ordinary law enforcement context — that is, only where there is some extraordinary governmental interest involved — is it legitimate to engage in a balancing test to determine whether a warrant is indeed necessary."
"We do not know what class petitioner was attending when the police and dogs burst in, but the lesson the school authorities taught her that day will undoubtedly make a greater impression than the one her teacher had hoped to convey. I would grant certiorari to teach petitioner another lesson: that the Fourth Amendment protects `[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures' . . . . Schools cannot expect their students to learn the lessons of good citizenship when the school authorities themselves disregard the fundamental principles underpinning our constitutional freedoms." Doe v. Renfrow, 451 U.S. 1022, 1027-1028 (1981) (dissenting from denial of certiorari). See also New Jersey v. T. L. O., 469 U. S., at 354 (BRENNAN, J., dissenting); id., at 373-374 (STEVENS, J., dissenting). Cf. 8 U. S. C. § 1423(2) (as a condition of naturalization, a person must have "a knowledge and understanding of the fundamentals of the history, and of the principles and form of government, of the United States").
The Government argues that giving a traveler the option of leaving the country rather than being forced to undergo lengthy custodial criminal investigations based on mere suspicion "is an unsatisfactory alternative because it would allow the suspect to escape apprehension and return to repeat his smuggling efforts another day. In addition, this approach would remove a disincentive to smuggling activity by materially reducing the risk of apprehension and prosecution." Brief for United States 17-18, n. 9. This is exactly the same argument made whenever courts enforce the safeguards of the Fourth Amendment, and we have consistently stressed that if constitutionally permissible investigative stops do not promptly uncover sufficient evidence to support an arrest, the detainee must be released as a necessary consequence of constitutional liberty. See, e. g., United States v. Place, supra, at 709-710; Florida v. Royer, supra, at 499 (plurality opinion) ("the police [may not] seek to verify their suspicions by means that approach the conditions of arrest"); Dunaway v. New York, supra, at 211-216; United States v. Brignoni-Ponce, 422 U.S. 873, 881-882 (1975).