Mr. Justice Brennan
delivered the opinion of the Court.
The question here is whether the claim of a federal prisoner that he was convicted on evidence obtained in an unconstitutional search and seizure is cognizable in a post-conviction proceeding under 28 U. S. C. § 2255.
Petitioner was tried and convicted in the District Court for the Eastern District of Missouri on charges of armed robbery of a federally insured savings and loan association. At trial, petitioner’s only defense was insanity. The Court of Appeals for the Eighth Circuit, on petitioner’s direct appeal, affirmed the conviction. Kaufman v. United States, 350 F. 2d 408 (1965).
Petitioner then filed this post-conviction proceeding under § 2255 and included a claim that the finding of sanity was based upon the improper admission of unlawfully seized evidence. After an evidentiary hearing, the District Judge, who had also presided at petitioner’s trial, denied relief with a written opinion. As respects the claim of unlawful search and seizure, the opinion states that: “The record does not substantiate this claim. In any event, this matter was not assigned as error on Kaufman’s appeal from conviction and is not available as a ground for collateral attack on the instant § 2255 motion.” 268 F. Supp. 484, 487 (1967). Petitioner’s applications to the District Court and the Court of Appeals for the Eighth Circuit for leave to appeal in forma pauperis were denied.
We treat the actions of the District Court and the Court of Appeals as grounded on the view consistently followed by the Court of Appeals that claims of unlawful search and seizure “are not proper matters to be presented by a motion to vacate sentence under § 2255 but can only be properly presented by appeal from the conviction.” Other courts of appeals have indicated a contra-ry view. In light of the importance of the issue in the administration of § 2255 we granted certiorari. 390 U. S. 1002 (1968). We reverse.
The authority of the federal courts to issue the writ of habeas corpus was incorporated in the very first grant of federal court jurisdiction made by the Judiciary Act of 1789, c. 20, § 14, 1 Stat. 81, with the limiting provision that “writs of habeas corpus shall in no case extend to prisoners in gaol, unless where they are in custody, under or by colour of the authority of the United States . . . .” Common-law principles initially determined the scope of the writ. Ex parte Bollman, 4 Cranch 75, 93-94 (1807). In 1867, however, the writ was extended to state prisoners, and its scope was expanded to authorize relief, both as to federal and state prisoners, in “all cases where any person may be restrained of his or her liberty in violation of the constitution, or of any treaty or law of the United States . . . .” Act of February 5, 1867, c. 28, § 1, 14 Stat. 385.
Section 2255 revised the procedure by which federal prisoners are to seek such relief but did not in any respect cut back the scope of the writ. The section was included in the 1948 revision of the Judicial Code “at the instance of the Judicial Conference [of the United States] to meet practical difficulties that had arisen in administering the habeas corpus jurisdiction of the federal courts. Nowhere in the history of Section 2255 do we find any purpose to impinge upon prisoners’ rights of collateral attack upon their convictions. On the contrary, the sole purpose was to minimize the difficulties encountered in habeas corpus hearings by affording the same rights in another and more convenient jorum,” United States v. Hayman, 342 U. S. 205, 219 (1952) (italics supplied); “the legislation was intended simply to provide in the sentencing court a remedy exactly commensurate with that which had previously been available by habeas corpus in the court of the district where the prisoner was confined.” Hill v. United States, 368 U. S. 424, 427 (1962). Thus, we may refer to our decisions respecting the availability of the federal habeas remedy in deciding the question presented in this case.
We noted in Fay v. Noia, 372 U. S. 391, 409 (1963) that “[t]he course of decisions of this Court . . . makes plain that restraints contrary to our fundamental law, the Constitution, may be challenged on federal habeas even though imposed pursuant to the conviction of a federal court of competent jurisdiction.” We have given the same recognition to constitutional claims in § 2255 proceedings. See, e. g., United States v. Hayman, supra; Sanders v. United States, 373 U. S. 1 (1963); Jordan v. United States, 352 U. S. 904 (1956). The courts of appeals which have denied cognizance under § 2255 to unconstitutional search-and-seizure claims have not generally supplied reasons supporting their apparent departure from this course of our decisions. Rather, these courts have made the bald statement, variously expressed, that a motion under § 2255 cannot be used in lieu of an appeal. It is true that in Sunal v. Large, 332 U. S. 174,179 (1947), we held that “the writ is not designed for collateral review of errors of law committed by the trial court — the existence of any evidence to support the conviction, irregularities in the grand jury procedure, departure from a statutory grant of time in which to prepare for trial, and other errors in trial procedure which do not cross the jurisdictional line.” But we there recognized that federal habeas relief for constitutional claims asserted by federal prisoners is not limited by that rule. 332 U. S., at 182; see also Hill v. United States, supra, at 428. Later, in Townsend v. Sain, 372 U. S. 293, 311-312 (1963), we pointed out the vital distinction between the appellate and habeas functions and concluded that habeas relief cannot be denied solely on the ground that relief should have been sought by appeal to prisoners alleging constitutional deprivations:
“The whole history of the writ — its unique development — refutes a construction of the federal courts’ habeas corpus powers that would assimilate their task to that of courts of appellate review. The function on habeas is different. It is to test by way of an original civil proceeding, independent of the normal channels of review of criminal judgments, the very gravest allegations. . . . The language of Congress, the history of the writ, the decisions of this Court, all make clear that the power of inquiry on federal habeas corpus is plenary. Therefore, where an applicant for a writ of habeas corpus alleges facts which, if proved, would entitle him to relief, the federal court to which the application is made has the power to receive evidence and try the facts anew.”
The Government suggests another rationale for denying post-conviction relief to federal prisoners with illegal search-and-seizure claims. The denial of Fourth Amendment protection against unreasonable searches and seizures, the Government’s argument runs, is of a different nature from denials of other constitutional rights which we have held subject to collateral attack by federal prisoners. -For unlike a claim of denial of effective counsel or of violation of the privilege against self-incrimination, as examples, a claim of illegal search and seizure does not impugn the integrity of the fact-finding process or challenge evidence as inherently unreliable; rather, the exclusion of illegally seized evidence is simply a prophylactic device intended generally to deter Fourth Amendment violations by law enforcement officers. This deterrent function, the Government argues, is adequately served by the opportunities afforded a federal defendant to enforce the exclusionary rule before or at trial, so that the relatively minimal additional deterrence afforded by a post-conviction remedy would not seem to justify, except in special circumstances, the collateral release of guilty persons who did not raise the search-and-seizure issue at trial or on direct appeal. In sum, the Government sponsors adoption by this Court of the rule announced in the majority opinion of the Court of Appeals for the District of Columbia Circuit in Thornton v. United States, 125 U. S. App. D. C. 114, 116, 368 F. 2d 822, 824 (1966), that in the absence of a showing of “special circumstances” a claim by a federal prisoner that evidence admitted at his trial was the fruit of an unconstitutional search or seizure is not properly the ground of a collateral attack on his conviction.
The Government concedes in its brief that we have already rejected this approach with respect to the availability of the federal habeas corpus remedy to state prisoners. This rejection was premised in large part on a recognition that the availability of collateral remedies is necessary to insure the integrity of proceedings at and before trial where constitutional rights are at stake. Our decisions leave no doubt that the federal habeas remedy extends to state prisoners alleging that unconstitutionally obtained evidence was admitted against them at trial. See, e. g., Mancusi v. DeForte, 392 U. S. 364 (1968); Carafas v. LaVallee, 391 U. S. 234 (1968); Warden v. Hayden, 387 U. S. 294 (1967); see also Henry v. Mississippi, 379 U. S. 443, 452 (1965). The Government argues, however, that federal post-conviction relief should not be available to federal prisoners in as broad a range of cases as that cognizable when presented by state prisoners. Support for this proposition is drawn from the fact that considerations which this Court, in Fay v. Noia, supra, deemed justifications for affording a federal forum to state prisoners — e. g., the necessity that federal courts have the “last say” with respect to questions of federal law, the inadequacy of state procedures to raise and preserve federal claims, the concern that state judges may be unsympathetic to federally created rights, the institutional constraints on the exercise of this Court’s certiorari jurisdiction to review state convictions — do not obtain with respect to federal prisoners. Thus, we are told that the federal prisoner, having already had his day in federal court, stands in a different position with regard to federal collateral remedies than does the state prisoner. Conceding this distinction, we are unable to understand why it should lead us to restrict, completely or severely, access by federal prisoners with illegal search- and-seizure claims to federal collateral remedies, while placing no similar restriction on access by state prisoners.
The opportunity to assert federal rights in a federal forum is clearly not the sole justification for federal post-conviction relief; otherwise there would be no need to make such relief available to federal prisoners at all. The provision of federal collateral remedies rests more fundamentally upon a recognition that adequate protection of constitutional rights relating to the criminal trial process requires the continuing availability of a mechanism for relief. This is no less true for federal prisoners than it is for state prisoners.
In Townsend v. Sain, supra, at 313, 318, we set down the circumstances under which a federal court must review constitutional claims- — including, of course, claims of illegal search and seizure — presented by state prisoners:
“If (1) the merits of the factual dispute were not resolved in the state hearing; (2) the state factual determination is not fairly supported by the record as a whole; (3) the fact-finding procedure employed by the state court was not adequate to afford a full and fair hearing; (4) there is a substantial allegation of newly discovered evidence; (5) the material facts were not adequately developed at the state-court hearing; or (6) for any reason it appears that the state trier of fact did not afford the habeas applicant a full and fair fact hearing.
“In all other cases where the material facts are in dispute, the holding of such a hearing is in the discretion of the district judge.”
Of these, only the duty of the federal habeas court to scrutinize “the fact-finding procedure” under (3) does not apply in the case of a federal prisoner; federal fact-finding procedures are by hypothesis adequate to assure the integrity of the underlying constitutional rights. Thus, when a request for relief under § 2255 asserts a claim of unconstitutional search and seizure which was tested by a motion to suppress at or before trial under Fed. Rule Crim. Proc. 41 (e), the § 2255 court need not stop to review the adequacy of the procedure established by that Rule. In this respect, and in this respect only, the position of the federal prisoner does differ from that of the state prisoner. We perceive no differences between the situations of state and federal prisoners which should make allegations of the other circumstances listed in Townsend v. Sain less subject to scrutiny by a § 2255 court.
The approach adopted by the court in Thornton and pressed upon us here exalts the value of finality in criminal judgments at the expense of the interest of each prisoner in the vindication of his constitutional rights. Such regard for the benefits of finality runs contrary to the most basic precepts of our system of post-conviction relief. In Fay v. Noia, supra, at 424, a case involving a state prisoner who claimed that his confession was coerced, we said that “conventional notions of finality in criminal litigation cannot be permitted to defeat the manifest federal policy that federal constitutional rights of personal liberty shall not be denied without the fullest opportunity for plenary federal judicial review.” The same view was expressed in Sanders v. United States, supra, at 8, a case involving a federal prisoner: “ [conventional notions of finality of litigation have no place where life or liberty is at stake and infringement of constitutional rights is alleged.” This philosophy inheres in our recognition of state prisoners’ post-conviction claims of illegal search and seizure. Plainly the interest in finality is the same with regard to both federal and state prisoners. With regard to both, Congress has determined that the full protection of their constitutional rights requires the availability of a mechanism for collateral attack. The right then is not merely to a federal forum but to full and fair consideration of constitutional claims. Federal prisoners are no less entitled to such consideration than are state prisoners. There is no reason to treat federal trial errors as less destructive of constitutional guarantees than state trial errors, nor to give greater preclusive effect to procedural defaults by federal defendants than to similar defaults by state defendants. To hold otherwise would reflect an anomalous and erroneous view of federal-state relations.
We cannot agree with the suggestion in Mr. Justice Black’s dissent that the weight to be accorded the benefits of finality is as controlling in the context of post-conviction relief as in the context of retroactive relief. The availability of post-conviction relief serves significantly to secure the integrity of proceedings at or before trial and on appeal. No such service is performed by extending rights retroactively. Thus, collateral relief, unlike retroactive relief, contributes to the present vitality of all constitutional rights whether or not they bear on the integrity of the fact-finding process.
More fundamentally, the logic of his dissent cannot be limited to the availability of post-conviction relief. It brings into question the propriety of the exclusionary rule itself. The application of that rule is not made to turn on the existence of a possibility of innocence; rather, exclusion of illegally obtained evidence is deemed necessary to protect the right of all citizens, not merely the citizen on trial, to be secure against unreasonable searches and seizures. As we said in Miller v. United States, 357 U. S. 301, 313 (1958):
“We are duly mindful of the reliance that society must place for achieving law and order upon the enforcing agencies of the criminal law. But insistence on observance by law officers of traditional fair procedural requirements is, from the long point of view, best calculated to contribute to that end. However much in a particular case insistence upon such rules may appear as a technicality that inures to the benefit of a guilty person, the history of the criminal law proves that tolerance of short-cut methods in law enforcement impairs its enduring effectiveness. . . . Every householder, the good and the bad, the guilty and the innocent, is entitled to the protection designed to secure the common interest against unlawful invasion of the house.”
Finally, Mr. Justice Black’s reliance on petitioner’s concession of participation in the robbery is misplaced. That concession is irrelevant in light of petitioner’s defense at trial based on insanity. Surely that defense, any more than any other defense, cannot be prejudiced by the admission of unconstitutionally seized evidence.
We thus reject the rule announced in the majority opinion in Thornton and adopt the reasoning of Judge Wright’s dissent in that case, 125 U. S. App. D. C., at 123, 368 F. 2d, at 831:
“There is undoubtedly a difference in the way federal courts should treat post-conviction applications by state and federal prisoners. Brown v. Allen, [344 U. S. 443, 508], 73 S. Ct. 397 (opinion of Mr. Justice Frankfurter), interprets 28 U. S. C. § 2241 as requiring federal courts to have the 'last say’ with respect to questions of federal law. Federal prisoners applying for collateral relief often have had their constitutional claims passed on by federal courts at trial or on appeal, so the Brown v. Allen rationale for federal court relitigation is inapposite. But this difference provides no basis for limiting the grounds upon which federal prisoners may obtain collateral relief, or for formulating a separate set of rules to determine when a federal prisoner’s claim has adequately been adjudicated. Where a federal trial or appellate court has had a ‘say’ on a federal prisoner’s claim, there may be no need for collateral relitigation. But what if the federal trial or appellate court said nothing because the issue was not raised? What if it is unclear whether the ‘say’ was on the merits? What if new law has been made or facts uncovered relating to the constitutional claim since the trial and appeal? What if the trial or appellate court based its rulings on findings of fact made after a hearing not ‘full and fair’ within the meaning of Townsend v. Sain, 372 U. S. 293, 83 S. Ct. 745, 9 L. Ed. 2d 770 (1963)? All these problems are common to state and federal prisoners, and the interest in finality operates equally in both situations. These problems raise, not the issue whether relitigation is necessary, but whether one adequate litigation has been afforded. It would be anomalous indeed, especially in light of the interest in maintaining good federal-state relations, if defaults not precluding one adequate federal review for the constitutional claims of state prisoners precluded such a review for federal prisoners, or if defects rendering state court adjudications inadequate did not similarly affect federal court adjudications.”
We therefore hold that a claim of unconstitutional search and seizure is cognizable in a § 2255 proceeding. The order of the Court of Appeals is reversed and the case is remanded for further proceedings consistent with this opinion.
It is so ordered.
Mr. Justice Marshall took no part in the consideration or decision of this case.
The pertinent provisions of 28 17. S. C. §2255 are:
“A prisoner in custody under sentence of a court established by Act of Congress claiming the right to be released upon the ground that the sentence was imposed in violation of the Constitution or laws of the United States, or that the court was without jurisdiction to impose such sentence, or that the sentence was in excess of the maximum authorized by law, or is otherwise subject to collateral attack, may move the court which imposed the sentence to vacate, set aside or correct the sentence.
“A motion for such relief may be made at any time.
“Unless the motion and the files and records of the case conclusively show that the prisoner is entitled to no relief, the court shall cause notice thereof to be served upon the United States attorney, grant a prompt hearing thereon, determine the issues and make findings of fact and conclusions of law with respect thereto. If the court finds that the . . . sentence imposed was not authorized by law or otherwise open to collateral attack, or that there has been such a denial or infringement of the constitutional rights of the prisoner as to render the judgment vulnerable to collateral attack, the court shall vacate and set the judgment aside and shall discharge the prisoner or resentence him or grant a new trial or correct the sentence as may appear appropriate.
“A court may entertain and determine such motion without requiring the production of the prisoner at the hearing.
“The sentencing court shall not be required to entertain a second or successive motion for similar relief on behalf of the same prisoner.”
Petitioner initiated the § 2255 proceeding by a pro se motion. The only claim presented was denial of effective assistance of counsel. The District Judge ordered a hearing, and appointed counsel to assist petitioner. Counsel filed a supplemental motion presenting two additional claims, one of which was that the search of petitioner’s automobile was illegal.
Warren v. United States, 311 F. 2d 673, 675 (1963); see also Springer v. United States, 340 F. 2d 950 (1965); Peters v. United States, 312 F. 2d 481 (1963); Gendron v. United States, 340 F. 2d 601 (1965). Accord: United States v. Re, 372 F. 2d 641 (C. A. 2d Cir. 1967); United States v. Jenkins, 281 F. 2d 193 (C. A. 3d Cir. 1960); Armstead v. United States, 318 F. 2d 725 (C. A. 5th Cir. 1963); Eisner v. United States, 351 F. 2d 55 (C. A. 6th Cir. 1965); De Welles v. United States, 372 F. 2d 67 (C. A. 7th Cir. 1967); Williams v. United States, 307 F. 2d 366 (C. A. 9th Cir. 1962).
We have not overlooked that the District Court’s statement that “this matter was not assigned as error on Kaufman’s appeal from conviction . . .” suggests that in any event failure to appeal the conviction renders the § 2255 remedy unavailable. This suggestion is contrary to our decisions that failure to take a direct appeal from conviction does not deprive a federal post-conviction court of power to adjudicate the merits of constitutional claims; the question rather is whether the case is one in which refusal to exercise that power would be appropriate. See Fay v. Noia, 372 U. S. 391, 438-440 (1963); Henry v. Mississippi, 379 U. S. 443, 451-452 (1965).
This certainly is not a case where there was a “deliberate by-pass” of a direct appeal. Appointed counsel had objected at trial to the admission of certain evidence on grounds of unlawful search and seizure, but newly appointed appellate counsel did not assign the admission as error either in his brief or on oral argument of the appeal. After oral argument of the appeal, however, petitioner wrote a letter to appellate counsel asking him to submit to the Court of Appeals a claim of illegal search and seizure of items from his automobile. Counsel forwarded petitioner’s letter to the Clerk of the Court of Appeals who notified counsel that petitioner’s letter had been given to the panel which had heard and was considering the appeal. The opinion of the Court of Appeals affirming petitioner’s conviction does not appear to pass on the search-and-seizure claim.
United States v. Sutton, 321 F. 2d 221 (C. A. 4th Cir. 1963); Gaitan v. United States, 317 F. 2d 494 (C. A. 10th Cir. 1963).
Among the serious administrative problems under habeas corpus practice in the case of federal prisoners was that created by the requirement that the action be brought in the district of confinement, where the records of the case were often not readily available. Section 2255 changed this to require an application by motion filed in the sentencing court. See United States v. Hayman, 342 U. S. 205, 212-219 (1952).
See, e. g., Ex parte Lange, 18 Wall. 163 (1874); Ex parte Wilson, 114 U. S. 417 (1885); Callan v. Wilson, 127 U. S. 540 (1888); Counselman v. Hitchcock, 142 U. S. 547 (1892); Johnson v. Zerbst, 304 U. S. 458 (1938); Bowen v. Johnston, 306 U. S. 19 (1939); Waley v. Johnston, 316 U. S. 101 (1942); Von Moltke v. Gillies, 332 U. S. 708 (1948); see also cases collected in Fay v. Noia, 372 U. S. 391, 409, n. 17.
See, e. g., “A motion under § 2255 cannot be made the substitute for an appeal,” Peters v. United States, supra, n. 3, at 482 (C. A. 8th Cir.); “Section 2255 provides for a collateral attack on a judgment of conviction and is not a substitute for appeal for alleged errors committed at the trial,” Eisner v. United States, supra, n. 3, at 57 (C. A. 6th Cir.); “Questions concerning the admissibility of evidence obtained directly or indirectly as a result of an unlawful search can be reviewed on an appeal from a judgment of conviction, but cannot be dealt with in a section 2255 proceeding,” Williams v. United States, supra, n. 3, at 367 (C. A. 9th Cir.); “It has long been the law that habeas corpus and § 2255 will not be allowed to do service as an appeal, and that so far as federal prisoners are concerned, failure to appeal will normally bar resort to post-conviction relief,” Nash v. United States, 342 F. 2d 366, 367 (C. A. 5th Cir. 1965). These paraphrase the statement in Sunal v. Large, 332 U. S. 174, 178 (1947), that “the writ of habeas corpus will not be allowed to do service for an appeal,” but that statement was made in the context of an alleged nonconstitutional trial error. See United States v. Sobell, 314 F. 2d 314, 322-323 (C. A. 2d Cir. 1963).
Where a trial or appellate court has determined the federal prisoner’s claim, discretion may in a proper case be exercised against the grant of a § 2255 hearing. Section 2255 provides for hearing “[u]nless the motion and the files and records of the case conclusively show that the prisoner is entitled to no relief . . . In Sanders v. United States, 373 U. S. 1 (1963), we announced standards governing the determination whether a hearing should be ordered in the case of a successive motion under § 2255. Similarly, where the trial or appellate court has had a “say” on a federal prisoner’s claim, it may be open to the § 2255 court to determine that on the basis of the motion, files, and records, “the prisoner is entitled to no relief.” See Thornton v. United States, 125 U. S. App. D. C. 114, 125, 368 F. 2d 822, 833 (1966) (dissenting opinion of Wright, J.).
Furthermore, the §2255 court may in a proper case deny relief to a federal prisoner who has deliberately bypassed the orderly federal procedures provided at or before trial and by way of appeal — e. g., motion to suppress under Fed. Rule Crim. Proc. 41 (e) or appeal under Fed. Rule App. Proc. 4 (b). Fay v. Noia, supra, n. 3, at 438; Henry v. Mississippi, supra, n. 3, at 451-452.