NORRIS, Circuit Judge:
These consolidated appeals present the question whether the exclusionary rule bars the Immigration and Naturalization Service (INS) from using in deportation proceedings evidence obtained by INS officers in violation of the Fourth Amendment. In separate proceedings, appellants were ordered deported under 8 U.S.C. § 1251(a)(2) on the basis of admissions to immigration officers that they were aliens in this country illegally. At their deportation hearings, both tried unsuccessfully to suppress evidence of their admissions on the ground they were the products of arrests made in violation of the Fourth Amendment.1 The immigration judge in Sandoval’s case ruled [1061]*1061the evidence admissible on the ground that Sandoval’s detention did not violate the Fourth Amendment. The immigration judge in Lopez’s case held that the exclusionary rule was inapplicable in deportation proceedings, making it unnecessary for him to decide whether Lopez had been unlawfully detained by immigration officers. The appeals of both Sandoval and Lopez from their respective deportation orders were dismissed by the Board of Immigration Appeals. Both appealed directly to this court. We have jurisdiction under 8 U.S.C. § 1105a (1976).
We reverse Sandoval’s order of deportation because we hold that his detention by the immigration officers violated the Fourth Amendment, that the statements he made were a product of that unlawful detention, and that the exclusionary rule bars the INS from using, in deportation proceedings, evidence of statements it obtains illegally. Because the question whether Lopez’s detention violated the Fourth Amendment was not adjudicated in his deportation hearing, we vacate his order of deportation and remand for further proceedings in light of our opinion today in Sandoval.
I
On June 23, 1977, INS officers entered a potato processing plant in Pasco, Washington, where Sandoval worked, to search for illegal aliens. According to the testimony of the government’s only witness, Officer Bower, the officers did not have a search warrant, but did have permission from company officials to question some of the company employees. Bower testified that several officers surrounded the plant to guard the exits while he and another officer conducted the investigation. The two officers, one of whom wore a Border Patrol uniform, first entered the company lunch room and identified themselves. This caused great confusion among company employees, with some “heading for the exits” and others remaining in the lunch room. When the officers entered the plant itself, more employees “headed for the exits, leaving their machines, and some of those coming in turned and started walking away.” The officers then moved to the plant’s main entrance where they stood during a shift change.' There, they watched for workers “putting their heads down, turning their heads to the sides, avoiding eye contact, or trying to get into a tight group of people going through.” Anyone passing through the gate who aroused suspicion in the minds of the officers was asked innocuous questions in English about such things as the weather or pay at the plant. Then, Bower testified,' “[tjhose that couldn’t answer in English, appeared to have a dumb look on their face, didn’t know what was going on, and would almost start to move towards me as if they had known they were caught and the game was up, at that point, I would interrogate them in Spanish as to their right to be and remain in the United States.”
When examined further about his criteria for stopping and questioning those entering and exiting the plant; Bower repeated that he had looked for “evasive movements, trying to be bunched up in groups, being right next to somebody, or trying to walk in parallel with somebody to avoid being spoken to ... . ” Eventually, he concluded, he questioned those at the plant “when it [came] to the point where I firmly believe that they are an illegal alien.” He knew that point because, “[i]t is something each officer develops, some sooner than some others.” After stopping a suspected illegal alien, the investigators would ask him whether he “had papers.” Though Sandoval was stopped at the plant, Officer Bower testified that he had no specific recollection of Sandoval and that there was a “50-50 chance” that he had detained Sandoval and an equal chance that his partner had effected the detention. Bower thus did not know how Sandoval had responded to any questions he may have been asked or, indeed, whether he had responded at all.
“Because of the large number of people coming in and out of there,” those initially stopped at the plant gate whom the officers wished to question further were detained in a men’s restroom and clean-up area. There [1062]*1062is no evidence in the record indicating whether Sandoval was questioned while in. the men’s room. Eventually, thirty-seven aliens who had been detained in the men’s room, including Sandoval, were transported to the Franklin County Jail and processed in the training room of the Pasco Police Department. Once the suspects arrived at the jail, they were sorted into two groups. Those who wished to depart for Mexico voluntarily were processed immediately and placed on a bus leaving that day. Those who demanded a deportation hearing were detained and processed later in the day. Sandoval was one of the latter group. During his processing, Sandoval was not orally advised of his rights but did read and refuse to sign Form 1-274, a Spanish-English language form which explains the right to a deportation hearing and to counsel. Sandoval was then asked a series of questions regarding his immigration status. Based on the answers to these questions, Officer Bower completed INS Form 1-213, indicating on the form that Sandoval was a native of Mexico and that he had entered the United States without inspection. The finding of alienage by the immigration law judge was based upon the Form I-213.2
In rejecting Sandoval’s contention that he had been seized in violation of the Fourth Amendment, the immigration judge reasoned that Sandoval “could have at some time ... reacted in a furtive manner in the presence of the officials” and that “[t]his plus foreign appearance would constitute enough articulable facts [to] give rise to a suspicion of alienage.”3 Accordingly, the judge ruled that Sandoval’s detention, first in the men’s room of the processing plant and later at the Franklin County Jail, did not violate the Fourth Amendment. On appeal, the BIA held that Sandoval’s statements were voluntary and found “no basis to conclude upon review of the record as a whole ... that the circumstances of the respondent’s arrest affected the statements contained in the Form 1-213.” The Board did not address the question of the legality of Sandoval’s arrest or the applicability of the exclusionary rule to his deportation proceeding.
On appeal to this court, Sandoval contends that because his statements were the product of an illegal arrest, the INS should be barred from using Form 1-213 as evidence in his deportation proceeding. The government first argues that Sandoval’s detention at the plant was at most an investigative stop and that the stop was lawful because the “officers’ observations were sufficient to support a reasonable suspicion of the illegal nature of petitioner’s alienage.” Yet Officer Bower could not remember Sandoval or describe his behavior. It is thus difficult to imagine that there was the requisite individualized suspicion of illegal alienage to justify even a brief Terry stop of Sandoval. See International Ladies Garment Workers Union v. Sureck, 681 F.2d 624, 634-43 (9th Cir.1982). Yet we need not decide that issue, for the dispositive question is not the lawfulness of the initial stop of Sandoval as he entered the plant, but the lawfulness of his detention at the time he was interrogated at the jail. It was there that Sandoval made the statements that were recorded by the INS agents on Form 1-213 and used against him at his deportation hearing. By the time of the interrogation at the police station, the initial stop had clearly ripened into an arrest. See Dunaway v. New York, 442 U.S. 200, 212, 99 S.Ct. 2248, 2256, 60 L.Ed.2d 824 (1979) (when a person is taken to a police station and placed in an interrogation room, the detention, “in contrast to the brief and narrowly circumscribed intrusion involved in [the Terry line of] cases ... [is] in impor[1063]*1063tant respects indistinguishable from a traditional arrest” and must be supported by probable cause). It is clear that there was no probable cause for Sandoval’s arrest. The furtive behavior attributed to the arrestees in Officer Bower’s testimony— “turning their heads to the sides,” “avoiding eye contact,” not answering questions asked in English, having “a dumb look”— was patently insufficient as a matter of law to “warrant a man of reasonable caution in the belief,” Carroll v. United States, 267 U.S. 132, 162, 45 S.Ct. 280, 288, 69 L.Ed. 543 (1925), that they were aliens illegally in this country. To its credit, the government does not argue to the contrary.
In sum, we must conclude on the record before us that Sandoval was under arrest at the time he was interrogated at the Franklin County Jail, and that because his arrest was not based upon probable cause, it violated the Fourth Amendment.4 The statements obtained from Sandoval at the police station were thus the fruit of an illegal arrest.5 The exclusionary rule would, of course, bar the use of such oral statements in a criminal prosecution of Sandoval for violation of the immigration laws. United States v. Brignoni-Ponce, 422 U.S. 873, 95 S.Ct. 2574, 45 L.Ed.2d 607 (1975). See also Brown v. Illinois, 422 U.S. 590, 601-05, 95 S.Ct. 2254, 2260-63, 45 L.Ed.2d 416 (oral statements made following illegal arrest suppressed; giving of Miranda warnings prior to statements did not, in itself, purge taint of illegal arrest). We now address the question whether that evidence — specifically, the Form 1-213 — is admissible in Sandoval’s deportation hearing.6
II
The question of the applicability of the exclusionary rule in deportation proceedings is one of first impression in this Circuit.' See Cuevas-Ortega v. Immigration and Naturalization Service, 588 F.2d 1274, 1278 (9th Cir.1979) (question expressly reserved); Hoonsilapa v. Immigration and Naturalization Service, 586 F.2d 755 (9th Cir.1978) (same). On the one occasion the Supreme Court has had to comment on the question, it stated in dictum that: “[i]t may be assumed that evidence obtained by the [Labor] Department through an illegal search and seizure cannot be the basis of a finding in deportation proceedings.” United States ex rel. Bilokumsky v. Tod, 263 U.S. 149, 155, 44 S.Ct. 54, 56, 68 L.Ed. 221 (1923). Although this language has been read by the First Circuit, Wong Chung Che v. Immigration and Naturalization Service, 565 F.2d 166, 169 (1st Cir.1977), and the [1064]*1064commentators, see, e.g., Comment, The Exclusionary Rule in Deportation Proceedings, 14 Davis L.Rev. 955, 957 (1981) (hereinafter cited as Exclusionary Rule Note), as approving application of the exclusionary rule, it remains unclear to us whether the Court was expressing a view on the issue or simply assuming arguendo that the rule applies in deportation proceedings. We are thus hesitant to attach significant precedential weight to Bilokumsky.
The few federal courts which have squarely confronted the question have all held that evidence illegally obtained by federal agents is inadmissible in subsequent deportation proceedings. The first case to so hold was United States v. Wong Quong Wong, 94 F. 832 (D.Vt.1899). Relying on Boyd v. United States, 116 U.S. 616, 6 S.Ct. 524, 29 L.Ed. 746 (1886) (evidence obtained in violation of the Fourth Amendment excluded from proceeding imposing forfeiture as penalty for criminal offence), the court in Wong Quong Wong reasoned that the “constitutional safeguards [of the Fourth Amendment] would be deprived of a large part of their value if they could be invoked only for preventing the obtaining of such evidence, and not for protection against its use.” United States v. Wong Quong Wong, 94 F. at 834. Some years later, in Ex parte Jackson, 263 F. 110, 112-13 (D.Mont.), appeal dismissed, 267 F. 1022 (9th Cir.1920), the district court granted a writ of habeas corpus to an alien held for deportation, stating that “the deportation proceedings [were] unfair and invalid, in that they [were] based on evidence and procedure that violate the search and seizure and due' process clauses of the Constitution.”
In 1977, the First Circuit held in Wong Chung Che v. Immigration and Naturalization Service, 565 F.2d 166 (1st Cir.1977) that evidence obtained in an illegal search by INS agents is inadmissible in a deportation proceeding. Although the court found the issue troublesome, it reasoned that “there is no authority of which we are aware that would make [the evidence] admissible [and] [s]uch authority as we have found ... assumes that it is inadmissible.” Id. at 169. In making this determination, the First Circuit relied both on Bilokumsky and on the leading treatise on immigration law, which stated unequivocally that the rule does apply to deportation proceedings. 1A C. Gordon and H. Rosenfield, Immigration Law and Procedure § 5.2.c at 5-31 (rev. ed. 1980) (“[I]t is undisputed .. . that the Fourth Amendment prohibition against unreasonable searches and seizures applies in deportation proceedings and that evidence obtained as a result of an unlawful search cannot be used”); see also Fragomen, Procedural Aspects of Illegal Search and Seizure in Deportation Cases, 14 San Diego L.Rev. 151, 163 (1976) (now well established that exclusionary rule applies despite universal characterization of deportation as civil proceeding). The First Circuit also cited to other cases in which it was assumed that the exclusionary rule applied in deportation proceedings. See Wong Chung Che v. Immigration and Naturalization Service, 565 F.2d at 169, citing Illinois Migrant Council v. Pilliod, 398 F.Supp. 882, 897-98 (N.D.Ill.1975) (if this were deportation proceeding, rather than exclusion hearing, illegally obtained evidence would be suppressed). See also Huerta-Cabrera v. Immigration and Naturalization Service, 466 F.2d 759, 761 n. 5 (7th Cir.1972) (stating that illegal arrest per se does not invalidate deportation proceeding but that “[t]his would not be a case of the use of evidence seized during the course of an illegal arrest.”); Yam Sang Kwai v. Immigration and Naturalization Service, 411 F.2d 683, 690 (D.C.Cir.1969) (Wright, J., dissenting) (“[I]n my view the statement was the fruit of an [illegal] seizure . .., and should not have been admitted”). But see Hoonsilapa v. Immigration and Naturalization Service, 586 F.2d 755 (9th Cir.1978) (reserving the question).7
Until 1979, in fact, the INS itself had assumed in “countless cases since ... U.S. ex. rel. Bilokumsky v. Tod, 263 U.S. 149, 155 [44 S.Ct. 54, 56, 68 L.Ed. 221,]” that the rule was applicable. Matter of Sandoval, 17 I & [1065]*1065N Dec. 70, 93 (Applemen, Bd. member, dissenting). See also In re Tsang, 14 I & N Dec. 1, 2 (BIA 1973) (rule concerning motions to suppress “which is applied in criminal cases, has been adopted for use in deportation hearings”). It was not until 1979, two years after Sandoval’s arrest, that the BIA8 for the first time held, in a case unrelated to this one, that the exclusionary rule does not bar the INS from using in deportation hearings evidence obtained by INS agents. Matter of Sandoval, 17 I & N Dec. 70, 93 (1979) (BIA 1979). In sanctioning the use of evidence seized by INS agents during an illegal search of an alien’s home, the BIA cut against the grain of its own historic practice and the views of every court and commentator to have considered the issue.
In sum, while the question whether the exclusionary rule applies in deportation proceedings is one of first impression in the Ninth Circuit, we do not write on a slate that is entirely clean. With the exception of the BIA, the authorities have uniformly favored exclusion of evidence obtained illegaily by INS agents. It is also significant that before the BIA’s decision in Matter of Sandoval, the INS performed its investigative and prosecutorial functions in a legal regime in which the exclusionary rule was thought to apply. Notwithstanding this prior history, we believe the question merits fresh consideration, especially in light of United States v. Janis, 428 U.S. 433, 96 S.Ct. 3021, 49 L.Ed.2d 1046 (1976), the only case in which the Supreme Court has squarely addressed the applicability of the exclusionary rule to civil proceedings. Because deportation proceedings are.deemed to be civil in nature, Woodby v. Immigration and Naturalization Service, 385 U.S. 276, 285, 87 S.Ct. 483, 487-88, 17 L.Ed.2d 362 (1966), we look to the Court’s analysis in Janis for guidance in determining whether to apply the rule here.9
Ill
In United States v. Janis, the Supreme Court held that the exclusionary rule did not bar the federal government from using in a civil tax proceeding evidence seized by [1066]*1066state law enforcement officers in violation of the Fourth Amendment. 428 U.S. at 459-60, 96 S.Ct. at 3034-35. In deciding Janis, the Court employed an analysis that does not foreclose application of the exclusionary rule in all civil proceedings.10 Rath[1067]*1067er, while noting that it had never invoked the rule in a purely civil proceeding, 428 U.S. at 447, 96 S.Ct. at 3028-29, the Court ' adopted an approach that calls for selective application of the rule in civil cases. Consistent with its view that the “prime purpose of the [exclusionary] rule ... is to deter future unlawful police conduct,”11 428 U.S. at 446, 96 S.Ct. at 3028, quoting United States v. Calandra, 414 U.S. 338, 347, 94 S.Ct. 613, 619, 38 L.Ed.2d 561 (1974), the Court in Janis made deterrence the touchstone of its analysis, inquiring whether application of the exclusionary rule in the case before it would produce a “substantial and efficient” deterrent effect. Id., 428 U.S. at 453, 96 S.Ct. at 3031. The analysis was not an empirical one, for there has been little “convincing empirical evidence on the effects of the rule.” 428 U.S. at 446, 96 S.Ct. at 3028. Instead, the Court’s evaluation of the deterrent effect of invoking the rule was based on “common sense” and on its “own assumptions of human nature and the interrelationship of the various components of the law enforcement system.” 428 U.S. at 459, 96 S.Ct. at 3034.
In deciding whether to apply the exclusionary rule in the civil case at issue in Janis, the Court balanced the deterrent benefit to be gained against the social cost of invoking the rule. The Court first focused on the likelihood that state police would be deterred from violating the Fourth Amendment if evidence they seized illegally was excluded from federal civil proceedings. The Court reasoned that “the deterrent effect of the exclusion of relevant evidence is highly attenuated when the ‘punishment’ imposed upon the offending .. . officer is the removal of that evidence from a civil suit by ... a different sovereign,” id. at 458, 96 S.Ct. at 3034. The Court did not believe that application of the exclusionary sanction in such a case would effectively deter state police because the use of evidence in federal civil proceedings is not within their “zone of primary interest.” Id. The strength of the connection between the purposes of the offending officers and the purposes of those seeking to use the illegal[1068]*1068ly seized evidence was critical to the Court’s assessment of the deterrent value of applying the rule: the closer the connection, the greater the marginal deterrent value of imposing the sanction. Conversely, the deterrent effect of the sanction was believed to be attenuated when the sovereign forbidden from using the evidence is not the same sovereign whose agents illegally obtained it.
As a second step in its analysis, the Court considered the extent to which the persons whose “conduct is to be controlled,” id. at 448, 96 S.Ct. at 3029, are already subject to the deterrent effects of the rule. In Janis, the Court reasoned that because evidence obtained illegally by state police was already inadmissible in both state and federal criminal proceedings, little if any additional deterrence of state police misconduct would be gained by excluding such evidence from federal civil proceedings.
Finally, the Court determined that the attenuated impact of excluding relevant evidence from a federal civil proceeding, coupled with the existing deterrent effect of the rule on state police, created a “situation in which the imposition of the exclusionary rule ... [was] unlikely to provide significant, much less substantial, additional deterrence.” Id. at 458, 96 S.Ct. at 3034. Accordingly, the Court had no difficulty in concluding, as the third step in its analysis, that the social cost of invoking the rule— hampering enforcement of admittedly valid laws by removing “concededly relevant and reliable evidence,” id. at 447, 96 S.Ct. at 3029 — outweighed its deterrent value in a civil case involving an intersovereign violation. The Court thus held that “the judicially created exclusionary rule should not be extended to forbid the use in the civil proceedings of one sovereign of evidence seized by a criminal law enforcement agent of another sovereign.” Id. at 459-60, 96 S.Ct. at 3034-35.
IV
A
Appellant Sandoval, in arguing that evidence unlawfully obtained by INS agents should be excluded from his deportation hearing, presents- us with a question expressly left open in Janis — -whether the exclusionary rule should be applied in civil cases involving “intrasovereign violations”: cases in which “the officer committing the unconstitutional search or seizure[s] [is] an agent of the [same] sovereign that [seeks] to use the evidence.” 428 U.S. at 455-56, n. 31, 96 S.Ct. at 3033. In deciding Sandoval’s appeal, however, we engage in the same inquiry the Court made in Janis, assessing the marginal deterrent benefit of imposing the exclusionary sanction against the INS, and weighing that effect against the social cost of excluding from deportation hearings evidence that is the product of unlawful conduct by INS agents.12
[1069]*1069The first step in the inquiry mandated by Janis is an examination of the connection between those who illegally obtained the evidence and those who seek to use it in subsequent proceedings. In this case, the connection could not be more direct: those who violated the Fourth Amendment in obtaining the evidence and those who seek to use it in deportation proceedings are members of the same government agency, the INS. Thus, we are presented not only with an intrasovereign violation, but with an intraagency violation as well. The connection between the offending officers and those who seek to use the tainted evidence is further strengthened by an identity of purpose between the two. The immigration officers who interrogated Sandoval after arresting him did so exclusively to aid in filling out INS Form 1-213, the form used by INS attorneys at Sandoval’s deportation hearing to prove his deportability. When, as here, the offending officer and the prosecutor share a common goal, the deterrent effect of the exclusionary sanction is maximized: an officer will have little incentive to violate the Fourth Amendment if he knows that tainted evidence will be worthless to the prosecutorial agency he serves. See Tirado v. Commissioner, 689 F.2d 307, 310-11 (2d Cir.1982).
Taking the second step of the Janis analysis, we find that applications of the exclusionary sanction outside the deportation context are not likely to be effective in deterring immigration officers from violating the Fourth Amendment. While it is true that evidence seized illegally could not be used if Sandoval were to be criminally prosecuted for violation of the immigration laws, deportation, not criminal prosecution, is clearly the prime concern of immigration officers. Aliens apprehended for violation of the immigration laws are rarely subjected to criminal prosecution; in the vast majority of cases, they are either allowed to depart voluntarily or are deported following formal proceedings. See United States Immigration and Naturalization Service, 1979 Annual Report 5, 20 (fewer than 2% of the deportable aliens who are apprehended are ever convicted of criminal violations). Thus, criminal prosecution is simply not within the immigration officer’s “zone of primary interest.” Janis, 428 U.S. at 458, [1070]*107096 S.Ct. at 3034. Contrary to the BIA’s conclusion in Matter of Sandoval, 17 I & N Dec. at 78, therefore, we deem it highly unlikely that immigration officers will be deterred from violating the Fourth Amendment by the prospect of unsuccessful criminal prosecutions.13
In sum, the Janis analysis, when applied here, compels the conclusion that the deterrent impact of invoking the rule in deportation proceedings will be “substantial and efficient.”14 Janis, 428 U.S. at 453, 96 S.Ct. at 3032. Not only are the officers seizing the evidence members of the same agency as those seeking to use it, they also share a common goal — the deportation of aliens in the country illegally. Finally, there are no other applications of the exclusionary rule which effectively deter the offending officers from violating the Fourth Amendment. If the exclusionary rule is the “ ‘strong medicine’ its proponents claim it to be,” Janis, 428 U.S. at 453, 96 S.Ct. at 3032, then we can imagine no more effective application than in these circumstances. Indeed, there is authority that the sanction is “routinely” applied in cases where the deterrent effect of its application is as great as it is here. See Tirado v. Commissioner, 689 F.2d at 310, 311 (rule “routinely” applied in “core” cases which “bar use of illegally seized items as affirmative evidence in the trial of the [very same] matter for which the search was conducted”).15 Nonetheless [1071]*1071we proceed, under the Janis analysis, to assess the social cost of applying the exclusionary rule in deportation proceedings and to balance that cost against the substantial deterrent impact of the sanction on INS misconduct.
B
The social cost of applying the exclusionary rule in deportation proceedings must be measured primarily in terms of the number of aliens who will succeed in escaping deportation by the suppression of illegally obtained evidence of their alienage or illegal status. When analyzed in these terms, it becomes clear that only an infinitesimal fraction of the illegal alien population will mount challenges based on the exclusionary rule and that the small number who do so successfully will not appreciably increase the number of illegal aliens in our midst.
Historically, the exclusionary rule has been invoked infrequently in deportation proceedings. As it noted in Matter of Sandoval, the BIA was able to find only_two reported immigration cases since 1899 in which the rule was applied to bar unlawfully seized evidence, only one other case in which the rule’s application was specifically addressed, and fewer than fifty BIA proceedings since 1952 in which a Fourth Amendment challenge to the introduction of evidence was even raised. 17 I & N Dec. at 80, 98-99.16 It is perhaps curious that the rule has been invoked so sparingly in deportation proceedings, especially in view of the fact that immigration law practitioners have been informed by the major treatise in their field that the exclusionary rule was available to clients facing deportation. See 1A C. Gordon and H. Rosenfield, Immigration Law and Procedure § 5.2c at 5-31 (rev. ed. 1980). One plausible explanation is that immigration officers have not committed many Fourth Amendment transgressions because they have been effectively deterred by the exclusionary rule. As noted above, the INS, at least before the BIA’s 1979 decision in Matter of Sandoval, operated in a legal regime in which the cases and commentators uniformly sanctioned the invocation of the rule in deportation proceedings.
A second plausible explanation for the paucity of challenges based on the exclusionary rule is the relative ease with which aliens who are apprehended may reenter the United States following voluntary departure. Approximately 85% of the aliens present in this country enter from Mexico, from which entry without inspection is not difficult. See Department of Justice, Special Study Group on Illegal Immigrants from Mexico: A Program for Effective and Humane Action on Illegal Mexican Immigration 6 (1973). Thus those facing deportation to Mexico may find it simpler to leave voluntarily with the thought of reentering the United States at a later time17 rather than remain to litigate the issue of their deportability.18
[1072]*1072Whatever the explanation, our holding today should result in no significant increase in the frequency with which the exclusionary rule is invoked in deportation proceedings. Hence, in assessing the social cost of holding that the rule bars the INS from using illegally., obtained evidence in deportation proceedings, we adopt the realistic premise that the number of aliens likely to escape deportation by invoking the rule is inconsequential. Moreover, whatever number do benefit from application of the rule is insignificant when compared with the flood of illegal immigrants who enter the United States each year. Although statistics on the number of aliens in this country illegally are necessarily unverifiable, available estimates indicate that there are from 2 to 12 million, and it is believed that over 500,000 more enter illegally each year. See Los Angeles Times, 1983 at 1, col. 3; Note, The Exclusionary Rule in Deportation Proceedings: Time for Alternatives, 14 J.Int’l L. & Econ. 349, 350 (1980) (5 million); Report of the Senate Judiciary Committee, S.Rep. 97-485, on S.2222 at 4 (97th Cong.1982) (citing estimates of the Select Commission on Immigration and Refugee Policy that 3.5 to 6 million illegal aliens were present as of 1978, and noting that “whatever the number four years ago, there are surely many more now”); United States v. Brignoni-Ponce, 422 U.S. 873, 878, 95 S.Ct. 2574, 2579, 45 L.Ed.2d 607 (1975) (12 million). If application of the rule results in aborted deportation proceedings in as many as one hundred cases a year — a number twice as great as the number of evidentiary challenges raised before the BIA since 1952 — the result would be an increase of less than one one thousandth of one percent in the illegal alien population. This is hardly an exorbitant price to pay for effective deterrence of INS misconduct. Indeed, the BIA itself has conceded that application of “the rule would not appear to have the potential to significantly impact on this country’s immigration laws and policies,” Matter of Sandoval, 17 I & N Dec. at 80.19
Thus the government cannot — and does not — base its argument about anticipated social costs on the numbers of illegal aliens who will succeed in remaining in this country by invoking the exclusionary rule.20 Rather, the principal concern of the government and the BIA seems to be that by permitting otherwise deportable aliens to remain in the country, the courts will be sanctioning a continuing violation of the immigration laws. Yet neither the BIA’s nor the government’s assessment of the seriousness of this problem withstands clos& scrutiny. It strikes us as far-fetched to suggest that sanctioning the continuing “status crime” of illegal alienage is as threatening or damaging to society as is releasing, without punishment, a person known to have violated other provisions of the criminal laws. Illegal aliens are not, as a class, per se dangerous to the law-abiding members of the community. In fact just the opposite is true. “Mexican immigrants show no evidence of rejecting fundamental American values and institutions,” Cornelius, Chavez & Castro, Mexican Immigrants and Southern California: A Summary of Current Knowledge 9 (1982), and common sense tells us that illegal aliens, fearing detection by authorities, have a special incentive to be law-abiding residents of this [1073]*1073country. In contrast, the tendency of persons who have once committed crimes to do so again is well documented, see, e.g., National Council on Crime and Delinquency, Uniform Parole Rep. Characteristics of the Parole Population, 1978 at 3 (1980) (26% of persons committed to prison had served one or more prior prison terms).
We recognize that the problem of illegal immigration is an intractable one. Despite the best efforts of the INS, millions of aliens have managed to enter this country without inspection and to remain here undetected. For various reasons, as Justice White noted seven years ago, “[t]he entire system [of enforcement of the immigration laws] has been notably unsuccessful in deterring or stemming [the] heavy flow of illegal immigrants.” United States v. Ortiz, 422 U.S. 891, 915, 95 S.Ct. 2585, 2598, 45 L.Ed.2d 623 (1975) (White, J., dissenting). Indeed, it has been estimated that 21,000 officers would be needed to control the 75-mile stretch of border at El Centro, California alone. Id. at 900 n. 2, 95 S.Ct. at 2590 (appendix to opinion of Burger, C.J., concurring). We thus appreciate the magnitude of the enforcement task that Congress has assigned the INS. We cannot believe, however, that the difficulty of the task would be perceptibly eased by exempting the INS from the exclusionary sanction.
Were we to give the INS a license to use tainted evidence in deportation proceedings, the agency could no doubt deport some handful of additional aliens who would otherwise escape deportation by invoking the rule. But surely the incremental social cost of harboring those few aliens who do succeed in escaping deportation on this basis and remain in the United States21 is inconsequential when compared with the marginal deterrence of INS misconduct to be gained by application of the rule. We thus conclude that the marginal deterrent benefit far outweighs the social cost of barring the INS from using in deportation proceedings evidence which its officers seize in violation of the Fourth Amendment.
Before holding that the rule must be applied in deportation proceedings, however, we treat the final contention advanced in Matter of Sandoval. Both the BIA in that case and the dissent here suggest that even if the deterrent effect of application of the exclusionary rule in the deportation context is substantial, there are less costly alternatives by which to achieve the rule’s goal of deterrence. We disagree. The alternatives proposed simply will not provide the deterrent necessary to ensure that official conduct comports with the Fourth Amendment.
C '
The alternatives to the exclusionary rule suggested by the BIA in Sandoval are both unrealistic and unacceptable. The BIA reasoned that the offending officer could be sued for damages in a Bivens22 action. Matter of Sandoval, 17 I & N Dec. at 82. Yet it is unlikely enough that citizens whose rights have been violated will bring a civil action for damages. It is even harder to imagine that illegal aliens — -particularly those who have been deported — will do so. See generally Exclusionary Rule Note, supra, at 369-70; Schroeder, Deterring Fourth Amendment Violations: Alternatives to the Exclusionary Rule 69 Geo.L.J. 1361, 1393 (1981) (“even damage actions that are pursued with reasonable frequency before an unbiased tribunal and against a financially able government ... are not an adequate substitute for the exclusionary rule.”) Over 97% of the illegal entrants apprehended by the Border Patrol in 1979 were Mexican nationals. United States Immigration and Naturalization Service, 1979 Statistical Yearbook of the Immigration and Naturalization Service, 80. These indi[1074]*1074viduals have a poor command of English, are fearful of authority and are unfamiliar with American culture and values. W. Cornelius, L. Chavez & J. Castro, supra, at 57-8. It is hard to believe that they are likely to possess the financial, emotional or cultural wherewithal to pursue a civil damage action against an INS officer when their rights have been violated.
Similarly, prospective injunctive relief, while effective in some circumstances, see, e.g., International Ladies Garment Workers Union v. Sureck, 681 F.2d 624 (9th Cir. 1982), is not a satisfactory alternative here. Injunctive relief is generally available only after broad scale violations that result from official policy, and is rarely, if ever, effective to deter violations that result not from official policy but from an individual officer’s overzealousness. See generally Exclusionary Rule Note, supra at 367-68; Schroeder, supra, at 1407-09.
The final alternative, internal discipline, presents a closer question. In theory, self-policing should be the most effective deterrent to illegal conduct because it offers the most direct and immediate feedback to the offending officer. Yet the practical experience of other law enforcement agencies indicates that internal review is rarely effective in deterring Fourth Amendment violations. See Schroeder, supra, at 1401-07; Note, The Administration of Complaints by Civilians Against the Police, 77 Harv.L.Rev. 499 (1964).
Judge Alarcon is apparently convinced that the INS system does not suffer the defects of other self-policing systems. See, infra, p. 1092 (Alarcon, J., dissenting). Yet, although his dissent cites at length from the INS disciplinary guidelines, it offers no evidence whatsoever that the guidelines are being consistently and effectively enforced. We agree that the INS has made a commendable effort to design an effective disciplinary system, but “[i]t would ... be myopic to presume from the existence of a remedy its effective and consistent implementation.” Exclusionary Rule Note, supra, at 371. Even if we could assume adequate enforcement of the INS guidelines, it would be unrealistic to assume that illegal aliens who have been the victims of unlawful behavior by INS agents will report their experiences to the INS. See Schroeder, supra, at 1402.
We are hopeful that the INS’ efforts will be an effective complement to the exclusionary rule. Yet we are hesitant to place sole responsibility for ensuring that citizens and aliens alike are free from unwarranted government intrusions into their privacy on the same officers responsible for patroling the borders and apprehending persons they suspect are aliens in this country illegally. As Justice Murphy observed in Wolf v. Colorado, 338 U.S. 25, 69 S.Ct. 1359, 93 L.Ed. 1782 (1949) (overruled by Mapp v. Ohio, 367 U.S. 643, 81 S.Ct. 1684, 6 L.Ed.2d 1081 (1961)), “[sjelf-scrutiny is a lofty ideal, but its exaltation reaches new heights if we expect a District Attorney to prosecute himself or his associates for well-meaning violations of the search and seizure clause during a raid the District Attorney or his associates have ordered.” 338 U.S. at 42, 69 S.Ct. at 1369 (Murphy J., dissenting).
CONCLUSION
In holding that evidence obtained by the INS in violation of the Fourth Amendment is inadmissible in subsequent deportation proceedings, we do not break new legal ground. Rather, we follow a line of case law directly on point broken only by the BIA’s split decision in Matter of Sandoval. We also follow a line of cases in which the exclusionary rule has been applied as a matter of routine where those who illegally seized evidence were of the same agency and pursuing the same law enforcement goals as those who sought to use it. Finally, although the Supreme Court has expressly reserved the question whether the rule applies in cases in which those who illegally seized the evidence are agents of the same sovereign who seeks to use it, we believe that its analysis in Janis dictates the result we reach in this particular case.
Until 1979, when the BIA decided Matter of Sandoval, immigration officers had been making arrests and seizing evidence appar[1075]*1075ently on the assumption that evidence they obtained in violation of the Fourth Amendment could not be used to prove illegal alienage. 17 I & N Dec. at 93 (Applemen, Bd. member, dissenting). There is no indication that the belief that the exclusionary rule applied significantly impaired the investigative or prosecutorial efforts of the INS. The 200,000 deportation cases successfully prosecuted between 1971 and 1979, the millions of voluntary departures during the same period, and the paucity of cases terminated because of Fourth Amendment violations belie such a notion. We simply cannot believe that our confirmation of the historic view that the exclusionary rule applies in deportation proceedings will seriously impede the INS in the discharge of its statutory duties. Indeed, as aptly put by the dissent in Matter of Sandoval, “[t]he rule having been accepted and followed for so many years, the natural inquiry is what reason is there for a change now?” Matter of Sandoval, 17 I & N Dee. at 94 (Apple-men, Bd. member, dissenting). Whatever the solution to the problem of illegal immigration, we do not think that it lies in judicial compromise of Fourth Amendment values.
If the Fourth Amendment is to retain its vitality as guardian of the privacy of citizens and non-citizens alike, the federal judiciary must be constantly vigilant in ensuring adherence- to its commands by those charged with enforcing our laws. We are convinced that the best and indeed the only realistic way to ensure that immigration officers respect the precious values embodied in the Fourth Amendment is to apply the exclusionary rule in deportation proceedings.
For the foregoing reasons, we hold that Sandoval’s statements were inadmissible in his deportation hearing and REVERSE his order of deportation. We VACATE Lopez’s order of deportation and REMAND his case for further proceedings consistent with this opinion.