opinion: UNITED STATES v. PELTIER
  No. 73-2000.
  Argued February 18, 1975 —
  Decided June 25, 1975
  William L. Patton argued the cause for the United States. On the brief were Solicitor General Bork, Acting Assistant Attorney General Keeney, Mark L. Evans, and Peter M. Shannon, Jr.
  Sandor W. Shapery, by appointment of the Court, 419 U. S. 1044, argued the cause and filed a brief for respondent.
  Sanford Jay Rosen filed a brief for the Mexican American Legal Defense and Educational Fund as amicus curiae urging affirmance.
  Mr. Justice Rehnquist
  delivered the opinion of the Court.
  Four months before this Court’s decision in Almeida-Sanchez v. United States, 413 U. S. 266 (1973), respondent was stopped in his automobile by a roving border patrol, and three plastic garbage bags containing 270 pounds of marihuana were found in the trunk of his car by Border Patrol agents. On the basis of this evidence an indictment was returned charging him with a violation of 84 Stat. 1260, 21 U. S. C. § 841 (a) (1). When respondent’s motion to suppress the evidence was denied after a hearing, he stipulated in writing that he “did knowingly and intentionally possess, with intent to distribute, the marijuana concealed in the 1962 Chevrolet which he was driving on February 28, 1973.” The District Court found respondent guilty and imposed sentence. On appeal from that judgment, the Court of Appeals for the Ninth Circuit, sitting en banc, reversed the judgment on the ground that the “rule announced by the Supreme Court in Almeida-Sanchez v. United States . . . should be applied to similar cases pending on appeal on the date the Supreme Court’s decision was announced.” 500 F. 2d 985, 986 (1974) (footnote omitted) . We granted the Government’s petition for certiorari. 419 U. S. 993 (1974).
  In Almeida-Sanchez, supra, this Court held that a warrantless automobile search, conducted approximately 25 air miles from the Mexican border by Border Patrol agents, acting without probable cause, was unconstitutional under the Fourth Amendment. In this case the Government conceded in the Court of Appeals that the search of respondent’s automobile approximately 70 air miles from the Mexican border and the seizure of the marihuana were unconstitutional under the standard announced in Almeida-Sanchez, but it contended that that standard should not be applied to searches conducted prior to June 21, 1973, the date of the decision in AlmeidaSanchez. In an inquiry preliminary to balancing the interests for and against retroactive application, see Stovall v. Denno, 388 U. S. 293, 297 (1967), the majority of the Court of Appeals first considered whether this Court had “articulated a new doctrine” in Almeida-Sanchez, 500 F. 2d, at 987. See, e. g., Chevron Oil Co. v. Huson, 404 U. S. 97, 106 (1971); Milton v. Wainwright, 407 U. S. 371, 381-382, n. 2 (1972) (Stewart, J., dissenting). Concluding that Almeida-Sanchez overruled no prior decision of this Court and instead “reaffirmed well-established Fourth Amendment standards” that did not “disturb a long-accepted and relied-upon practice,” 500 F. 2d, at 988, the Court of Appeals held:
  “[Respondent] is entitled to the benefit of the rule announced in Almeida-Sanchez, not because of retro-activity but because of Fourth Amendment principles never deviated from by the Supreme Court.” Id., at 989.
  The judgment of conviction was reversed, and the case was remanded to the District Court to suppress the evidence seized from respondent’s automobile.
  Although expressing some doubt about the applicability of the old law-new law test as a precondition to retro-activity analysis, id., at 990, the six dissenters joined issue with the majority over the proper interpretation of Almeida-Sanchez. The dissenters concluded that AlmeidaSanchez had announced a new constitutional rule because the decision overruled a consistent line of Courts of Appeals precedent and disrupted a long accepted and widely relied upon administrative practice. Border Patrol agents had conducted roving searches pursuant to congressional authorization, 66 Stat. 233, 8 U. S. C. § 1357 (a)(3), and administrative regulation, 8 CFR § 287.1 (a)(2) (1973), which had been continuously upheld until this Court’s decision in Almeida-Sanchez. Since Almeida-Sanchez stated a new rule, the dissenters concluded that the applicability of that decision to pre-June 21, 1973, roving patrol vehicle searches should be determined by reference to the standards summarized in Stovall v. Denno, supra. For the reasons expressed in Part II of Judge Wallace’s opinion in United States v. Bowen, 500 F. 2d 960, 975-981 (CA9), cert. granted, 419 U. S. 824 (1974), the dissenters concluded that Almeida-Sanchez should be accorded prospective application.
  Despite the conceded illegality of the search under the Almeida-Sanchez standard, the Government contends that the exclusionary rule should not be mechanically applied in the case now before us because the policies underlying the rule do not justify its retroactive application to pre-Almeida-Sanchez searches. We agree.
  I
  Since 1965 this Court has repeatedly struggled with the question of whether rulings in criminal cases should be given retroactive effect. In those cases “[w]here the major purpose of new constitutional doctrine is to overcome an aspect of the criminal trial that substantially impairs its truth-finding function and so raises serious questions about the accuracy of guilty verdicts in past trials,” Williams v. United States, 401 U. S. 646, 653 (1971), the doctrine has quite often been applied retroactively. It is indisputable, however, that in every case in which the Court has addressed the retroactivity problem in the context of the exclusionary rule, whereby coneededly relevant evidence is excluded in order to enforce a constitutional guarantee that does not relate to the integrity of the factfinding process, the Court has concluded that any such new constitutional principle would be accorded only prospective application. Linkletter v. Walker, 381 U. S. 618 (1965); Johnson v. New Jersey, 384 U. S. 719 (1966); Stovall v. Denno, supra; Fuller v. Alaska, 393 U. S. 80 (1968); Desist v. United States, 394 U. S. 244 (1969); Jenkins v. Delaware, 395 U. S. 213 (1969); Williams v. United States, supra; Hill v. California, 401 U. S. 797 (1971).
  We think that these cases tell us a great deal about the nature of the exclusionary rule, as well as something about the nature of retroactivity analysis. Decisions of this Court applying the exclusionary rule to unconstitutionally seized evidence have referred to “the imperative of judicial integrity,” Elkins v. United States, 364 U. S. 206, 222 (1960), although the Court has relied principally upon the deterrent purpose served by the exclusionary rule. See Mapp v. Ohio, 367 U. S. 643 (1961); Lee v. Florida, 392 U. S. 378 (1968); see also United States v. Calandra, 414 U. S. 338 (1974); Michigan v. Tucker, 417 U. S. 433 (1974). And see also Oaks, Studying the Exclusionary Rule in Search and Seizure, 37 U. Chi. L. Rev. 665, 668-672 (1970).
  When it came time to consider whether those decisions would be applied retroactively, however, the Court recognized that the introduction of evidence which had been seized by law enforcement officials in good-faith compliance with then-prevailing constitutional norms did not make the courts “accomplices in the willful disobedience of a Constitution they are sworn to uphold.” Elkins v. United States, supra, at 223. Thus, while the “imperative of judicial integrity” played a role in this Court’s decision to overrule Wolf v. Colorado, 338 U. S. 25 (1949), see Mapp v. Ohio, supra, at 659, the Mapp decision was not applied retroactively: “Rather than being abhorrent at the time of seizure in this case, the use in state trials of illegally seized evidence had been specifically authorized by this Court in Wolf.” Linkletter v. Walker, supra, at 638 (footnote omitted). Similarly, in Lee v. Florida, supra, this Court overruled Schwartz v. Texas, 344 U. S. 199 (1952), and held that evidence seized in violation of § 605 of the Federal Communications Act of 1934, 48 Stat. 1103, 47 IT. S. C. § 605, by state officers could not be introduced into evidence at state criminal trials:
  “[T]he decision we reach today is not based upon language and doctrinal symmetry alone. It is buttressed as well by the ‘imperative of judicial integrity.’ Elkins v. United States, 364 U. S. 206, 222. Under our Constitution no court, state or federal, may serve as an accomplice in the willful transgression of ‘the Laws of the United States,’ laws by which ‘the Judges in every State [are] bound ....’” 392 U. S., at 385-386 (footnotes omitted).
  But when it came time to consider the retroactivity of Lee, the Court held that it would not be applied retroactively, saying:
  “Retroactive application of Lee would overturn every state conviction obtained in good-faith reliance on Schwarts. Since this result is not required by the principle upon which Lee was decided, or necessary to accomplish its purpose, we hold that the exclusionary rule is to be applied only to trials in which the evidence is sought to be introduced after the date of our decision in Lee.” Fuller v. Alaska, supra, at 81.
  The teaching of these retroactivity cases is that if the law enforcement officers reasonably believed in good faith that evidence they had seized was admissible at trial, the “imperative of judicial integrity” is not offended by the introduction into evidence of that material even if decisions subsequent to the search or seizure have broadened the exclusionary rule to encompass evidence seized in that manner. It would seem to follow a fortiori from the Linkletter and Fuller holdings that the “imperative of judicial integrity” is also not offended if law enforcement officials reasonably believed in good faith that their conduct was in accordance with the law even if decisions subsequent to the search or seizure have held that conduct of the type engaged in by the law enforcement officials is not permitted by the Constitution. For, although the police in Linkletter and Fuller could not have been expected to foresee the application of the exclusionary rule to state criminal trials, they could reasonably have entertained no similar doubts as to the illegality of their conduct. See Wolf v. Colorado, 338 U. S., at 27; § 605 of the Federal Communications Act of 1934; cf. Nardone v. United States, 302 U. S. 379 (1937).
  This approach to the “imperative of judicial integrity” does not differ markedly from the analysis the Court has utilized in determining whether the deterrence rationale undergirding the exclusionary rule would be furthered by retroactive application of new constitutional doctrines. See Linkletter v. Walker, supra, at 636-637; Fuller v. Alaska, supra, at 81; Desist v. United States, supra, at 249-251. In Desist, the Court explicitly recognized the interrelation between retroactivity rulings and the exclusionary rule: “[W]e simply decline to extend the court-made exclusionary rule to cases in which its deterrent purpose would not be served.” 394 U. S., at 254 n. 24.
  This focus in the retroactivity cases on the purposes served by the exclusionary rule is also quite in harmony with the approach taken generally to the exclusionary rule. In United States v. Calandra, 414 U. S., at 348, we said that the exclusionary rule “is a judicially created remedy designed to safeguard Fourth Amendment rights generally through its deterrent effect, rather than a personal constitutional right of the party aggrieved.” It follows that “the application of the rule has been restricted to those areas where its remedial objectives are thought most efficaciously served.” Ibid. We likewise observed in Michigan v. Tucker, 417 U. S., at 447:
  “The deterrent purpose of the exclusionary rule necessarily assumes that the police have engaged in willful, or at the very least negligent, conduct which has deprived the defendant of some right. By refusing to admit evidence gained as a result of such conduct, the courts hope to instill in those particular investigating officers, or in their future counterparts, a greater degree of care toward the rights of an accused. Where the official action was pursued in complete good faith, however, the deterrence rationale loses much of its force.”
  The “reliability and relevancy,” Linkletter, supra, at 639, of the evidence found in the trunk of respondent’s car is unquestioned. It was sufficiently damning on the issue of respondent’s guilt or innocence that he stipulated in writing that in effect he had committed the offense charged. Whether or not the exclusionary rule should be applied to the roving Border Patrol search conducted in this case, then, depends on whether considerations of either judicial integrity or deterrence of Fourth Amendment violations are sufficiently weighty to require that the evidence obtained by the Border Patrol in this case be excluded.
  II
  The Border Patrol agents who stopped and searched respondent’s automobile were acting pursuant to § 287 (a) (3) of the Immigration and Nationality Act of 1952, 66 Stat. 233, 8 U. S. C. § 1357 (a)(3) That provision, which carried forward statutory authorization dating back to 1946, 60 Stat. 865, 8 U. S. C. § 110 (1946 ed.), authorizes appropriately designated Immigration and Naturalization officers to search vehicles “within a reasonable distance from any external boundary of the United States” without a warrant. Pursuant to this statutory authorization, regulations were promulgated fixing the “reasonable distance,” as specified in § 287 (a) (3), at “100 air miles from any external boundary of the United States,” 22 Fed. Reg. 9808 (1957), as amended, 29 Fed. Reg. 13244 (1964), 8 CFR § 287.1 (a) (2) (1973).
  Between 1952 and Almeida-Sanchez, roving Border Patrol searches under § 287 (a) (3) were upheld repeatedly against constitutional attack. Dicta in many other Fifth, Ninth, and Tenth Circuit decisions strongly suggested that the statute and the Border Patrol policy were acceptable means for policing the immigration laws. As Mr. Justice Powell observed in his concurring opinion in Almeida-Sanchez:
  “Roving automobile searches in border regions for aliens . . . have been consistently approved by the judiciary. While the question is one of first impression in this Court, such searches uniformly have been sustained by the courts of appeals whose jurisdictions include those areas of the border between Mexico and the United States where the problem has been most severe.” 413 U. S., at 278.
  It was in reliance upon a validly enacted statute, supported by longstanding administrative regulations and continuous judicial approval, that Border Patrol agents stopped and searched respondent’s automobile. Since the parties acknowledge that Almeida-Sanchez was the first roving Border Patrol case to be decided by this Court, unless we are to hold that parties may not reasonably rely upon any legal pronouncement emanating from sources other than this Court, we cannot regard as blameworthy those parties who conform their conduct to the prevailing statutory or constitutional norm. Cf. Chevron Oil Co. v. Huson, 404 U. S. 97 (1971); Lemon v. Kurtzman, 411 U. S. 192 (1973). If the purpose of the exclusionary rule is to deter unlawful police conduct then evidence obtained from a search should be suppressed only if it can be said that the law enforcement officer had knowledge, or may properly be charged with knowledge, that the search was unconstitutional under the Fourth Amendment. Admittedly this uniform treatment of roving border patrol searches by the federal judiciary was overturned by this Court’s decision in AlmeidaSanchez. But in light of this history and of what we perceive to be the purpose of the exclusionary rule, we conclude that nothing in the Fourth Amendment, or in the exclusionary rule fashioned to implement it, requires that the evidence here be suppressed, even if we assume that respondent’s Fourth Amendment rights were violated by the search of his car.
  The judgment of the Court of Appeals is therefore
  Reversed.
  Mr. Justice Stewart dissents from the opinion and judgment of the Court for the reasons set out in Part I of the dissenting opinion of Mr. Justice Brennan, post, at 544-549.
  App. 28. The stipulation provided that it “would not [have been] entered into- had the [respondent’s] motion to suppress in the case been granted.” Ibid.
  The Fifth Circuit had reached a contrary conclusion in United States v. Miller, 492 F. 2d 37 (1974).
  The Court acknowledged the “power of the Federal Government to exclude aliens from the country” and the constitutionality of “routine inspections and searches of individuals or conveyances seeking to cross our borders.” 413 U. S., at 272. While searches of this sort could be conducted “not only at the border itself, but at its functional equivalents as well,” ibid., the Court concluded that the search at issue in the case “was of a wholly different sort.” Id., at 273.
  388 U. S., at 297: “The criteria guiding resolution of the question [of retroactivity] implicate (a) the purpose to be served by the new standards, (b) the extent of the reliance by law enforcement authorities on the old standards, and (e) the effect on the administration of justice of a retroactive application of the new standards.”
  By the time Linkletter v. Walker, 381 U. S. 618 (1965), was decided, Mapp v. Ohio, 367 U. S. 643 (1961), had already been applied to three cases pending on direct review at the time Mapp was decided. Ker v. California, 374 U. S. 23 (1963); Fahy v. Connecticut, 375 U. S. 85 (1963); Stoner v. California, 376 U. S. 483 (1964). Those cases were decided without discussion of retroactivity principles, and they have not been interpreted as establishing any retroactivity limitation of general applicability. See Linkletter, supra, at 622; Johnson v. New Jersey, 384 U. S. 719, 732 (1966); Desist v. United States, 394 U. S. 244, 252-253 (1969).
  Title 8 U. S. C. § 1357 (a) (3):
  “Any officer or employee of the Service authorized under regulations prescribed by the Attorney General shall have power without warrant—
  “within a reasonable distance from any external boundary of the United States, to board and search for aliens any vessel within the territorial waters of the United States and any railway car, aircraft, conveyance, or vehicle, and within a distance of twenty-five miles from any such external boundary to have access to private lands, but not dwellings, for the purpose of patrolling the border to prevent the illegal entry of aliens into the United States.”
  “Any employee of the Immigration and Naturalization Service authorized so to do under regulations prescribed by the Commissioner of Immigration and Naturalization with the approval of the Attorney General, shall have power without warrant ... to board and search for aliens any vessel within the territorial waters of the United States, railway car, aircraft, conveyance, or vehicle, within a reasonable distance from any external boundary of the United States.”
  United States v. Thompson, 475 F. 2d 1359 (CA5 1973); Kelly v. United States, 197 F. 2d 162 (CA5 1952); Roa-Rodriquez v. United States, 410 F. 2d 1206 (CA10 1969); United States v. Miranda, 426 F. 2d 283 (CA9 1970); United States v. Almeida-Sanchez, 452 F. 2d 459 (CA9 1971), rev’d, 413 U. S. 266 (1973). In support of these holdings, the Courts of Appeals have relied upon cases sustaining searches and seizures at fixed checkpoints maintained within 100 air miles of the border. See nn. 9, 10, and 11, infra. Whether fixed-checkpoint searches and seizures are constitutional notwithstanding our decision in Almeida-Sanchez is before us in United States v. Ortiz, No. 73-2050, cert. granted, 419 U. S. 824 (1974); United States v. Bowen, 500 F. 2d 960 (CA9), cert. granted, 419 U. S. 824 (1974).
  Haerr v. United States, 240 F. 2d 533 (1957); Ramirez v. United States, 263 F. 2d 385 (1959); United States v. De Leon, 462 F. 2d 170 (1972), cert. denied, 414 U. S. 853 (1973).
  Fernandez v. United States, 321 F. 2d 283 (1963); Barba-Reyes v. United States, 387 F. 2d 91 (1967); United States v. Avey, 428 F. 2d 1159, cert. denied, 400 U. S. 903 (1970); Fumagalli v. United States, 429 F. 2d 1011 (1970); Mienke v. United States, 452 F. 2d 1076 (1971); United States v. Foerster, 455 F. 2d 981 (1972), vacated and remanded, 413 U. S. 915 (1973).
  United States v. McCormick, 468 F. 2d 68 (1972), cert. denied, 410 U. S. 927 (1973); United States v. Anderson, 468 F. 2d 1280 (1972).
  Mr. Justice Brennan’s dissent also suggests that we were wrong to reverse the judgment affirming Almeida-Sanchez’ conviction if we uphold the judgment of conviction against Peltier. But where it has been determined, as in a case such as Linkletter, that an earlier holding such as Mapp is not to be applied retroactively, it has not beeti questioned that Mapp was entitled to the benefit of the rule enunciated in her case. See Stovall v. Denno, 388 U. S., at 300-301. Nor did the Government in Almeida-Sanchez urge upon us any considerations of exclusionary rule policy independent of the merits of the Fourth Amendment question which we decided adversely to the Government.
  In its haste to extrapolate today’s decision, that dissent argues that this decision will both “stop dead in its tracks judicial development of Fourth Amendment rights” since “the first duty of a court will be to deny the accused’s motion to suppress if he cannot cite a case invalidating a search or seizure on identical facts” and add “a new layer of factfinding in deciding motions to suppress in the already heavily burdened federal courts.” Post, at 554, 560. Whether today’s decision will reduce the responsibilities of district courts, as the dissent first suggests, or whether that burden will be increased, as the dissent also suggests, it surely will not fulfill both of these contradictory prophecies. A fact not open to doubt is that the district courts are presently required, in hearing motions to suppress evidence, to spend substantial time addressing issues that do not go to a criminal defendant’s guilt or innocence. In this case, for example, the transcript of the suppression hearing takes almost three times as many pages in the Appendix as is taken by the transcript of respondent’s trial. App. 5-36.
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