with whom Justice Marshall joins, concurring in part and dissenting in part.
As part of its ongoing efforts to enforce the immigration laws, the Immigration and Naturalization Service (INS) conducts “surveys” of those workplaces that it has reason to believe employ large numbers of undocumented aliens who may be subject to deportation. This case presents the question whether the INS’s method of carrying out these “factory surveys”1 violates the rights of the affected factory workers to be secure against unreasonable seizures of one’s person as guaranteed by the Fourth Amendment. Answering that question, the Court today holds, first, that the INS surveys involved here did not result in the seizure of the entire factory work force for the complete duration of the surveys, ante, at 218-219, and, second, that the individual questioning of respondents by INS agents concerning their citizenship did not constitute seizures within the meaning of the Fourth Amendment, ante, at 219-221. Although I generally agree with the Court’s first conclusion,21 am convinced that a fair application of our prior decisions to the facts of this case *226compels the conclusion that respondents were unreasonably seized by INS agents in the course of these factory surveys.
At first blush, the Court’s opinion appears unremarkable. But what is striking about today’s decision is its studied air of unreality. Indeed, it is only through a considerable feat of legerdemain that the Court is able to arrive at the conclusion that the respondents were not seized. The success of the Court’s sleight of hand turns on the proposition that the interrogations of respondents by the INS were merely brief, “consensual encounters,” ante, at 221, that posed no threat to respondents’ personal security and freedom. The record, however, tells a far different story.
I — I
Contrary to the Court’s suggestion, see ante, at 216, we have repeatedly considered whether and, if so, under what circumstances questioning of an individual by law enforcement officers may amount to a seizure within the meaning of the Fourth Amendment. See, e. g., Terry v. Ohio, 392 U. S. 1 (1968); Davis v. Mississippi, 394 U. S. 721 (1969); Adams v. Williams, 407 U. S. 143 (1972); Brown v. Texas, 443 U. S. 47 (1979); United States v. Mendenhall, 446 U. S. 544 (1980); Florida v. Royer, 460 U. S. 491 (1983). Of course, as these decisions recognize, the question does not admit of any simple answer. The difficulty springs from the inherent tension between our commitment to safeguarding the precious, and all too fragile, right to go about one’s business free from unwarranted government interference, and our recognition that the police must be allowed some latitude in gathering information from those individuals who are willing to cooperate. Given these difficulties, it is perhaps understandable that our efforts to strike an appropriate balance have not produced uniform results. Nevertheless, the outline of what appears to be the appropriate inquiry has been traced over the years with some clarity.
*227The Court launched its examination of this issue in Terry v. Ohio, supra, by explaining that “the Fourth Amendment governs ‘seizures’ of the person which do not eventuate in a trip to the station house and prosecution for crime — ‘arrests’ in traditional terminology. It must be recognized that whenever a police officer accosts an individual and restrains his freedom to walk away, he has ‘seized’ that person.” Id., at 16 (emphasis added). Such a seizure, the Court noted, may be evidenced by either “physical force or show of authority” indicating that the individual’s liberty has been restrained. Id., at 19, n. 16. The essential teaching of the Court’s decision in Terry — that an individual’s right to personal security and freedom must be respected even in encounters with the police that fall short of full arrest — has been consistently reaffirmed. In Davis v. Mississippi, 394 U. S., at 726-727, for example, the Court confirmed that investigatory detentions implicate the protections of the Fourth Amendment and further explained that “while the police have the right to request citizens to answer voluntarily questions concerning unsolved crimes they have no right to compel them to answer.” Id., at 727, n. 6. Similarly, in Brown v. Texas, supra, we overturned a conviction for refusing to stop and identify oneself to police, because, in making the stop, the police lacked any “reasonable suspicion, based on objective facts, that the individual [was] involved in criminal activity.” Id., at 51. The animating principle underlying this unanimous decision was that the Fourth Amendment protects an individual’s personal security and privacy from unreasonable interference by the police, even when that interference amounts to no more than a brief stop and questioning concerning one’s identity.
Although it was joined at the time by only one other Member of this Court, Part II-A of Justice Stewart’s opinion in United States v. Mendenhall, supra, offered a helpful, preliminary distillation of the lessons of these cases. Noting *228first that “as long as the person to whom questions are put remains free to disregard the questions and walk away, there has been no intrusion upon that person’s liberty or privacy,” Justice Stewart explained that “a person has been ‘seized’ within the meaning of the Fourth Amendment only if, in view of all of the circumstances surrounding the incident, a reasonable person would have believed that he was not free to leave.” Id., at 554. The opinion also suggested that such circumstances might include “the threatening presence of several officers, the display of a weapon by an officer, some physical touching of the person of the citizen, or the use of language or tone of voice indicating that compliance with the officer’s request might be compelled.” Ibid.
A majority of the Court has since adopted that formula as the appropriate standard for determining when inquiries made by the police cross the boundary separating merely consensual encounters from forcible stops to investigate a suspected crime. See Florida v. Royer, 460 U. S., at 502, (plurality opinion); id., at 511-512 (Brennan, J., concurring in result); id., at 514 (Blackmun, J., dissenting). This rule properly looks not to the subjective impressions of the person questioned but rather to the objective characteristics of the encounter which may suggest whether or not a reasonable person would believe that he remained free during the course of the questioning to disregard the questions and walk away. See 3 W. LaFave, Search and Seizure §9.2, p. 52 (1978). The governing principles that should guide us in this difficult area were summarized in the Royer plurality opinion:
“[L]aw enforcement officers do not violate the Fourth Amendment by merely approaching an individual on the street or in another public place, by asking him if he is willing to answer some questions, by putting questions to him if the person is willing to listen, or by offering in evidence in a criminal prosecution his voluntary answers to such questions. Nor would the fact that the officer identifies himself as a police officer, without more, con*229vert the encounter into a seizure requiring some level of objective justification. The person approached, however, need not answer any question put to him; indeed, he may decline to listen to the questions at all and may go on his way. He may not be detained even momentarily without reasonable, objective grounds for doing so; and his refusal to listen or answer does not, without more, furnish those grounds.” 460 U. S., at 497-498 (citations omitted) (emphasis added).
Applying these principles to the facts of this case, I have no difficulty concluding that respondents were seized within the meaning of the Fourth Amendment when they were accosted by the INS agents and questioned concerning their right to remain in the United States. Although none of the respondents was physically restrained by the INS agents during the questioning, it is nonetheless plain beyond cavil that the manner in which the INS conducted these surveys demonstrated a “show of authority” of sufficient size and force to overbear the will of any reasonable person. Faced with such tactics, a reasonable person could not help but feel compelled to stop and provide answers to the INS agents’ questions. The Court’s efforts to avoid this conclusion are rooted more in fantasy than in the record of this case. The Court goes astray, in my view, chiefly because it insists upon considering each interrogation in isolation as if respondents had been questioned by the INS in a setting similar to an encounter between a single police officer and a lone passerby that might occur on a street corner. Obviously, once the Court begins with such an unrealistic view of the facts, it is only a short step to the equally fanciful conclusion that respondents acted voluntarily when they stopped and answered the agents’ questions.
The surrounding circumstances in this case are far different from an isolated encounter between the police and a passerby on the street. Each of the respondents testified at length about the widespread disturbance among the workers *230that was sparked by the INS surveys and the intimidating atmosphere created by the INS’s investigative tactics. First, as the respondents explained, the surveys were carried out by surprise by relatively large numbers of agents, generally from 15 to 25, who moved systematically through the rows of workers who were seated at their work stations. See App. 77-78, 81-85, 102-103, 122-123. Second, as the INS agents discovered persons whom they suspected of being illegal aliens, they would handcuff these persons and lead them away to waiting vans outside the factory. See id., at 88, 140-141. Third, all of the factory exits were conspicuously guarded by INS agents, stationed there to prevent anyone from leaving while the survey was being conducted. See id., at 48, 82, 125-126, 144-145, 158. Finally, as the INS agents moved through the rows of workers, they would show their badges and direct pointed questions at the workers. In light of these circumstances, it is simply fantastic to conclude that a reasonable person could ignore all that was occurring throughout the factory and, when the INS agents reached him, have the temerity to believe that he was at liberty to refuse to answer their questions and walk away.
Indeed, the experiences recounted by respondents clearly demonstrate that they did not feel free either to ignore the INS agents or to refuse to answer the questions posed to them. For example, respondent Delgado, a naturalized American citizen, explained that he was standing near his work station when two INS agents approached him, identified themselves as immigration officers, showed him their badges, and asked him to state where he was born. Id., at 95. Delgado, of course, had seen all that was going on around him up to that point and naturally he responded. As a final reminder of who controlled the situation, one INS agent remarked as they were leaving Delgado that they would be coming back to check him out again because he spoke English too well. Id., at 94. Respondent Miramontes described her encounter with the INS in similar terms: “He *231told me he was from Immigration, so when I showed him the [work permit] papers I saw his badge. If I hadn’t [seen his badge], I wouldn’t have shown them to him.” Id., at 121 (emphasis added). She further testified that she was frightened during this interview because “normally you get nervous when you see everybody is scared, everybody is nervous.” Ibid. Respondent Labontes testified that while she was sitting at her machine an immigration officer came up to her from behind, tapped her on the left shoulder and asked “Where are your papers?” Explaining her response to this demand, she testified: “I turned, and at the same time I didn’t wish to identify myself. When I saw [the INS agents], I said, ‘Yes, yes, I have my papers.’” Id., at 138 (emphasis added).
In sum, it is clear from this testimony that respondents felt constrained to answer the questions posed by the INS agents, even though they did not wish to do so. That such a feeling of constraint was reasonable should be beyond question in light of the surrounding circumstances. Indeed, the respondents’ testimony paints a frightening picture of people subjected to wholesale interrogation under conditions designed not to respect personal security and privacy, but rather to elicit prompt answers from completely intimidated workers. Nothing could be clearer than that these tactics amounted to seizures of respondents under the Fourth Amendment.3
*232H-1
The Court’s eagerness to conclude that these interrogations did not represent seizures is to some extent understandable, of course, because such a conclusion permits the Court to avoid the imposing task of justifying these seizures on the basis of reasonable, objective criteria as required by the Fourth Amendment.
The reasonableness requirement of the Fourth Amendment applies to all seizures of the person, including those that involve only a brief detention short of traditional arrest. But because the intrusion upon an individual’s personal security and privacy is limited in cases of this sort, we have explained that brief detentions may be justified on “facts that do not amount to the probable cause required for an arrest. ” United States v. Brignoni-Ponce, 422 U. S. 873, 880 (1975). Nevertheless, our prior decisions also make clear that investigatory stops of the kind at issue here “must be justified by some objective manifestation that the person stopped is, or is about to be, engaged in criminal activity.” United States v. Cortez, 449 U. S. 411, 417 (1981). As the Court stated in Terry, the “demand for specificity in the information upon which police action is predicated is the central teaching of this Court’s Fourth Amendment jurisprudence.” 392 U. S., at 21, n. 18. Repeatedly, we have insisted that police may not detain and interrogate an individual unless they have reasonable grounds for suspecting that the person is involved in some unlawful activity. In United States v. Brignoni-Ponce, supra, for instance, the Court held that “[Border Patrol] officers on roving patrol may stop vehicles only if they are aware of specific articulable facts, together with rational inferences from those facts, that reasonably warrant suspicion that the vehicles contain aliens who may be illegally in the country.” Id., at 884. See also Michigan v. Summers, 452 U. S. 692, 699-700 (1981); Ybarra v. Illinois, 444 U. S. 85, 92-93 (1979); Brown v. Texas, 443 U. S., at 51 — 52; Dela*233ware v. Prouse, 440 U. S. 648, 661 (1979); Adams v. Williams, 407 U. S., at 146-149; Davis v. Mississippi, 394 U. S., at 726-728; Terry v. Ohio, 392 U. S., at 16-19. This requirement of particularized suspicion provides the chief protection of lawful citizens against unwarranted governmental interference with their personal security and privacy.
In this case, the individual seizures of respondents by the INS agents clearly were neither “based on specific, objective facts indicating that society’s legitimate interests require[d] the seizure,” nor “carried out pursuant to a plan embodying explicit, neutral limitations on the conduct of individual officers.” Brown v. Texas, supra, at 51. It is undisputed that the vast majority of the undocumented aliens discovered in the surveyed factories had illegally immigrated from Mexico. Nevertheless, the INS agents involved in this case apparently were instructed, in the words of the INS Assistant District Director in charge of the operations, to interrogate “virtually all persons employed by a company.” App. 49. See also id., at 77, 85-86, 151-152, 155. Consequently, all workers, irrespective of whether they were American citizens, permanent resident aliens, or deportable aliens, were subjected to questioning by INS agents concerning their right to remain in the country. By their own admission, the INS agents did not selectively question persons in these surveys on the basis of any reasonable suspicion that the persons were illegal aliens. See id., at 55, 155. That the INS policy is so indiscriminate should not be surprising, however, since many of the employees in the surveyed factories who are lawful residents of the United States may have been bom in Mexico, have a Latin appearance, or speak Spanish while at work. See id., at 57, 73. What this means, of course, is that the many lawful workers who constitute the clear majority at the surveyed workplaces are subjected to surprise questioning under intimidating circumstances by INS agents who have no reasonable basis for suspecting that they have *234done anything wrong. To say that such an indiscriminate policy of mass interrogation is constitutional makes a mockery of the words of the Fourth Amendment.
Furthermore, even if the INS agents had pursued a firm policy of stopping and interrogating only those persons whom they reasonably suspected of being aliens, they would still have failed, given the particular circumstances of this case, to safeguard adequately the rights secured by the Fourth Amendment. The first and in my view insurmountable problem with such a policy is that, viewed realistically, it poses such grave problems of execution that in practice it affords virtually no protection to lawful American citizens working in these factories. This is so because, as the Court recognized in Brignoni-Ponce, supra, at 886, there is no reliable way to distinguish with a reasonable degree of accuracy between native-born and naturalized citizens of Mexican ancestry on the one hand, and aliens of Mexican ancestry on the other.4 See also Developments, Immigration Policy and the Rights of Aliens, 96 Harv. L. Rev. 1286, 1374-1375 (1983). Indeed, the record in this case clearly demonstrates this danger, since respondents Correa and Delgado, although both American citizens, were subjected to questioning during the INS surveys.
*235Moreover, the mere fact that a person is believed to be an alien provides no immediate grounds for suspecting any illegal activity. Congress, of course, possesses broad power to regulate the admission and exclusion of aliens, see Kliendeinst v. Mandel, 408 U. S. 753, 766 (1972); Fiallo v. Bell, 430 U. S. 787, 792 (1977), and resident aliens surely may be required to register with the INS and to carry proper identification, see 8 U. S. C. §§ 1302, 1304(e). Nonetheless, as we held in Brignoni-Ponce, 422 U. S., at 883-884, when the Executive Branch seeks to enforce such congressional policies, it may not employ enforcement techniques that threaten the constitutional rights of American citizens. In contexts such as these factory surveys, where it is virtually impossible to distinguish fairly between citizens and aliens, the threat to vital civil rights of American citizens would soon become intolerable if we simply permitted the INS to question persons solely on account of suspected alienage. Cf. id., at 884-886. Therefore, in order to protect both American citizens and lawful resident aliens, who are also protected by the Fourth Amendment, see Almeida-Sanchez v. United States, 413 U. S. 266, 273 (1973), the INS must tailor its enforcement efforts to focus only on those workers who are reasonably suspected of being illegal aliens.5
*236Relying upon United States v. Martinez-Fuerte, 428 U. S. 543 (1976), however, Justice Powell would hold that the interrogation of respondents represented a “reasonable” seizure under the Fourth Amendment, even though the INS agents lacked any particularized suspicion of illegal alienage to support the questioning, ante, at 224. In my view, reliance on that decision is misplaced. In Martinez-Fuerte, the Court held that when the intrusion upon protected privacy interests is extremely limited, the INS, in order to serve the pressing governmental interest in immigration enforcement, may briefly detain travelers at fixed checkpoints for questioning solely on the basis of “apparent Mexican ancestry.” 428 U. S., at 563. In so holding, the Court was careful to distinguish its earlier decision in Brignoni-Ponce, supra, which held that Border Patrol agents conducting roving patrols may not stop and question motorists solely on the basis of apparent Mexican ancestry, and may instead make such stops only when their observations lead them “reasonably to suspect that a particular vehicle may contain aliens who are illegally in the country.” Id., at 881. The “crucial distinction” between the roving patrols and the fixed checkpoints, as the Court later observed in Delaware v. Prouse, 440 U. S., at 656, was “the lesser intrusion upon the motorist’s Fourth Amendment interests” caused by the checkpoint operations. Thus, as the Court explained in Martinez-Fuerte: “This objective intrusion — the stop itself, the questioning, and the visual inspection — also existed in roving-patrol stops. But we view checkpoint stops in a different light because the subjective intrusion — the generating of concern or even fright on the part of lawful travelers — is appreciably less in the case of a checkpoint stop.” 428 U. S., at 558.6
*237The limited departure from Terry’s, general requirement of particularized suspicion permitted in Martinez-Fuerte turned, therefore, largely on the fact that the intrusion upon motorists resulting from the checkpoint operations was extremely modest. In this case, by contrast, there are no equivalent guarantees that the privacy of lawful workers will not be substantially invaded by the factory surveys or that the workers will not be frightened by the INS tactics. Indeed, the opposite is true. First, unlike the fixed checkpoints that were upheld in Martinez-Fuerte in part because their location was known to motorists in advance, the INS factory surveys are sprung upon unsuspecting workers completely by surprise. Respondents testified that the sudden arrival of large numbers of INS agents created widespread fear and anxiety among most workers. See App. 89, 107, 116, 120-121, 129-130. Respondent Miramontes, for instance, explained that she was afraid during the surveys “[b]ecause if I leave and they think I don’t have no papers and they shoot me or something. They see me leaving and they think I’m guilty.” Id., at 127.7 In Martinez-Fuerte, there was absolutely no evidence of widespread fear and anxiety similar to that adduced in this case.
Second, the degree of unfettered discretionary judgment exercised by the individual INS agents during the factory surveys is considerably greater than in the fixed checkpoint operations. The power of individual INS agents to decide who they will stop and question and who they will pass over contributes significantly to the feeling of uncertainty and *238anxiety of the workers. See App. 86, 90, 129-130. Unlike the fixed checkpoint operation, there can be no reliable sense among the affected workers that the survey will be conducted in an orderly and predictable manner. Third, although the workplace obviously is not as private as the home, it is at the same time not without an element of privacy that is greater than in an automobile. All motorists expect that while on the highway they are subject to general police surveillance as part of the regular and expectable enforcement of traffic laws. For the average employee, however, the workplace encloses a small, recognizable community that is a locus of friendships, gossip, common effort, and shared experience. While at work, therefore, the average employee will not have the same sense of anonymity that is felt when one is driving on the public highways; instead, an employee will be known by co-workers and will recognize other employees as his or her fellows. This experience, common enough among all who work, forms the basis for a legitimate, albeit modest, expectation of privacy that cannot be indiscriminately invaded by government agents. See Mancusi v. DeForte, 392 U. S. 364, 368-369 (1968) (employee has reasonable expectation of privacy in office space shared with other workers). The mere fact that the employer has consented to the entry of the INS onto his property does not mean that the workers’ expectation of privacy evaporates.
Finally, there is no historical precedent for these kinds of surveys that would make them expectable or predictable. As the Court noted in Martinez-Fuerte, supra, at 560-561, n. 14, road checkpoints are supported to some extent by a long history of acceptance that diminishes substantially the concern and fear that such practices would elicit in the average motorist. But factory surveys of the kind conducted by the INS are wholly unprecedented, and their novelty can therefore be expected to engender a high degree of resentment and anxiety. In sum, although the governmental interest is obviously as substantial here as it was in Martinez-*239Fuerte, the degree of intrusion upon the privacy rights of lawful workers is significantly greater. Accordingly, the quantum of suspicion required to justify such an intrusion must be correspondingly greater.
In my view, therefore, the only acceptable alternatives that would adequately safeguard Fourth Amendment values in this context are for the INS either (a) to adopt a firm policy of stopping and questioning only those workers who are reasonably suspected of being illegal aliens, or (b) to develop a factory survey program that is predictably and reliably less intrusive than the current scheme under review. The first alternative would satisfy the requirement of particularized suspicion enunciated in Terry — a principle that must control here because the specific conditions that permitted exception to that requirement in Martinez-Fuerte are simply not present. The second alternative would seek to redesign the factory survey techniques used by the INS in order to bring them more closely into line with the characteristics found in Martinez-Fuerte. Such a scheme might require the INS, before conducting a survey of all workers in a particular plant, to secure an administrative warrant based upon a showing that reasonable grounds exist for believing that a substantial number of workers employed at the factory are undocumented aliens subject to deportation, and that there are no practical alternatives to conducting such a survey. Cf. Camara v. Municipal Court, 387 U. S. 523 (1967). In addition, the surveys could be further tailored in duration and manner so as to be substantially less intrusive.
HH HH hH
No one doubts that the presence of large numbers of undocumented aliens in this country creates law enforcement problems of titanic proportions for the INS. Nor does anyone question that this agency must be afforded considerable latitude in meeting its delegated enforcement responsibilities. I am afraid, however, that the Court has become so *240mesmerized by the magnitude of the problem that it has too easily allowed Fourth Amendment freedoms to be sacrificed. Before we discard all efforts to respect the commands of the Fourth Amendment in this troubling area, however, it is worth remembering that the difficulties faced by the INS today are partly of our own making.
The INS methods under review in this case are, in my view, more the product of expedience than of prudent law enforcement policy. The Immigration and Nationality Act establishes a quota-based system for regulating the admission of immigrants to this country which is designed to operate primarily at our borders. See 8 U. S. C. §§ 1151-1153, 1221-1225. See generally Developments, 96 Harv. L. Rev., at 1334-1869. With respect to Mexican immigration, however, this system has almost completely broken down. This breakdown is due in part, of course, to the considerable practical problems of patroling a 2,000-mile border; it is, however, also the result of our failure to commit sufficient resources to the border patrol effort. See Administration’s Proposals on Immigration and Refugee Policy: Joint Hearing before the Subcommittee on Immigration, Refugees, and International Law of the House Committee on the Judiciary, and the Subcommittee on Immigration and Refugee Policy of the Senate Committee on the Judiciary, 97th Cong., 1st Sess., 6 (1981) (statement of Attorney General Smith); see also Developments, 96 Harv. L. Rev., at 1439. Furthermore, the Act expressly exempts American businesses that employ undocumented aliens from all criminal sanctions, 8 U. S. C. § 1324(a), thereby adding to the already powerful incentives for aliens to cross our borders illegally in search of employment.8
*241In the face of these facts, it seems anomalous to insist that the INS must now be permitted virtually unconstrained discretion to conduct wide-ranging searches for undocumented aliens at otherwise lawful places of employment in the interior of the United States. What this position amounts to, I submit, is an admission that since we have allowed border enforcement to collapse and since we are unwilling to require American employers to share any of the blame, we must, as a matter of expediency, visit all of the burdens of this jury-rigged enforcement scheme on the privacy interests of completely lawful citizens and resident aliens who are subjected to these factory raids solely because they happen to work alongside some undocumented aliens.9 The average American, as we have long recognized, see Carroll v. United States, 267 U. S. 132, 154 (1925), expects some interference with his or her liberty when seeking to cross the Nation’s borders, but until today’s decision no one would ever have expected the same treatment while lawfully at work in the country’s interior. Because the conditions which spawned such expedient solutions are in no sense the fault of these *242lawful workers, the Court, as the guardian of their constitutional rights, should attend to this problem with greater sensitivity before simply pronouncing the Fourth Amendment a dead letter in the context of immigration enforcement. The answer to these problems, I suggest, does not lie in abandoning our commitment to protecting the cherished rights secured by the Fourth Amendment, but rather may be found by reexamining our immigration policy.
I dissent.
The enforcement activities of the INS are divided between “border patrol” operations conducted along the border and its functional equivalents and “area control” operations conducted in the interior of the United States. The INS’s area control operations are in turn divided into traffic control operations (such as maintaining fixed checkpoints on major highways) and factory surveys of the kind at issue in this case.
It seems to me that the Court correctly finds that there was no single continuing seizure of the entire work force from the moment that the INS agents first secured the factory exits until the completion of the survey. I join the Court’s judgment in this respect because it is apparent that in all three factory surveys under review most of the employees were generally free while the survey was being conducted to continue working without interruption and to move about the workplace. Having said that, however, I should emphasize that I find the evidence concerning the conduct of the factorywide survey highly relevant to determining whether the individual respondents were seized. See infra, at 229-231.
Although respondents insist that the circumstances of these interrogations were sufficiently coercive to constitute a “seizure” under the Fourth Amendment, they do not contend that these interviews were conducted under conditions that might be labeled “custodial”; they do not argue, therefore, that the questioning by INS agents posed any threat to the privilege against self-incrimination protected by the Fifth Amendment. Cf. Miranda v. Arizona, 384 U. S. 436 (1966). Accordingly, it is not necessary to consider whether INS agents should be required to warn respondents of the possible incriminating consequences of providing answers to the agents’ questions.
As we explained in Brignoni-Ponce: “Large numbers of native-born and naturalized citizens have the physical characteristics identified with Mexican ancestry, and even in the border area a relatively small proportion of them are aliens.” 422 U. S. at 886.
Indeed, the proposition that INS agents, even those who have considerable experience in the field, will be able fairly and accurately to distinguish between Spanish-speaking persons of Mexican ancestry who are either native-born or naturalized citizens, and Spanish-speaking persons of Mexican ancestry who are aliens is both implausible and subject to discriminatory abuse. The protection of fundamental constitutional rights should not depend upon such unconstrained administrative discretion, for, as we have often observed, “[w]hen , . . a stop is not based on objective criteria, the risk of arbitrary and abusive police practices exceeds tolerable limits.” Brown v. Texas, 443 U. S. 47, 52 (1979).
Of course, as the Government points out, see Brief for Petitioners 35-38, § 287(a)(1) of the Immigration and Nationality Act provides that INS officers may, without a warrant, “interrogate any alien or person believed to be an alien as to his right to be or to remain in the United States.” 66 Stat. 238, 8 U. S. C. § 1357(a)(1). We have held, however, that broad statutory authority of this kind does not license the INS to employ unconstitutional enforcement methods. Almeida-Sanchez v. United States, 413 U. S., at 272-273. Because of that concern, the Court in United States v. Brignoni-Ponce, 422 U. S. 873 (1975), expressly left open the question whether INS officers “may stop persons reasonably believed to be aliens when there is no reason to believe they are illegally in the country.” Id., at 884, n. 9. In my view, given the particular constitutional dangers posed by the INS’s present method of carrying out factory surveys, the exercise of the authority granted by § 287(a)(1) must be limited to interrogations of only those persons reasonably believed to be in the country illegally.
Indeed, in Martinez-Fuerte, the Court repeatedly emphasized that, in contrast to the roving patrol stops, the fixed checkpoint operations are less likely to frighten motorists. This was so because “[m]otorists using these highways are not taken by surprise as they know . . . the location of the *237checkpoints and will not be stopped elsewhere,” and because the operations “both appear to and actually involve less discretionary enforcement activity.” 428 U. S., at 559.
See also United States Commission on Civil Rights, The Tarnished Golden Door: Civil Rights Issues in Immigration 90-91 (1980) (noting that “[t]estimony received by the Commission indicates that... INS area control operations do cause confusion and pandemonium among all factory employees, thereby disrupting a factory’s operations and decreasing production”).
The enormous law enforcement problems resulting from this combination of practical difficulties in patrolling this border and the incentives for illegal aliens to secure employment have been noted by the Congress, see Hearings on Oversight of the Immigration and Naturalization Service before the Subcommittee on Immigration, Citizenship and International *241Law of the House Committee on the Judiciary, 95th Cong., 2d Sess. (1978); and also by a Select Commission on Immigration and Refugee Policy, see United States Immigration Policy and the National Interest, Final Report of the Select Commission on Immigration and Refugee Policy 46, 61-62, 72-73 (1981).
In this regard, the views expressed in Justice White’s concurring opinion in United States v. Ortiz, 422 U. S. 891, 915 (1975), are particularly pertinent:
“The entire [immigration enforcement] system, however, has been notably unsuccessful in deterring or stemming this heavy flow [of illegal immigration]; and its costs, including added burdens on the courts, have been substantial. Perhaps the Judiciary should not strain to accommodate the requirements of the Fourth Amendment to the needs of a system which at best can demonstrate only minimal effectiveness as long as it is lawful for business firms and others to employ aliens who are illegally in the country. This problem, which ordinary law enforcement has not been able to solve, essentially poses questions of national policy and is chiefly the business of Congress and the Executive Branch rather than the courts.”