opinion: GILES et al. v. MARYLAND.
  No. 27.
  Argued October 12, 1966.
  Decided February 20, 1967.
  Joseph Forer argued the cause for petitioners. With him on the briefs was Hal Witt.
  Donald Needle, Assistant Attorney General of Maryland, and Robert C. Murphy, Deputy Attorney General, argued the cause for respondent. With them on the brief was Thomas B. Finan, Attorney General.
  Mr. Justice Brennan
  announced the judgment of the Court and an opinion in which The Chief Justice and Mr. Justice Douglas join.
  In December 1961, petitioners, who are brothers, were convicted of rape of a 16-year-old girl after trial by jury in the Circuit Court for Montgomery County, Maryland. In May 1964, petitioners brought this proceeding under Maryland’s Post-Conviction Procedure Act, Md. Ann. Code Art. 27, § 645Á (1966 Supp.). Their petition alleged that the prosecution denied them due process of law in violation of the Fourteenth Amendment by suppressing evidence favorable to them, and by the knowing use of perjured testimony against, them. An evidentiary hearing was had before Montgomery Circuit Judge Moorman who, in an unreported opinion, ruled that the proofs did not sustain the allegation of bad faith or knowing use of perjured testimony by the prosecution, but did establish the suppression of evidence which, although not in bad faith, constituted a denial of due process. He therefore ordered a new trial. The Court of Appeals of Maryland, sitting en banc, reversed, two judges dissenting. State v. Giles, 239 Md. 458, 212 A. 2d 101. We granted certiorari. 383 U. S. 941. We would vacate the judgment of the Maryland Court of Appeals and remand to that court for further proceedings.
  The rape allegedly occurred about midnight, July 20, 1961, near Rocky Gorge, a swimming and fishing spot on the Patuxent River, in a secluded, wooded area of Montgomery County. The petitioners swam and fished there from early evening with Joseph Johnson and John Bowie. The prosecutrix came there by automobile shortly before midnight with her date, Stewart Foster, and two other young men. Their car ran out of gasoline near Bowie’s parked car. The girl and Foster remained in the car while the other young men went for gasoline.
  The girl and Foster were the State’s principal witnesses. They testified that they had been sitting in the back seat of the car for some 15 minutes after the two young men left when a noise near Bowie’s car attracted their attention. They saw petitioners and their companions loading something into Bowie’s car. Bowie drove away and petitioners and Johnson approached the stranded car. Foster rolled up tbe windows and locked the doors. The girl and Foster testified that the three demanded his money and his girl and smashed the car windows with rocks to open the car doors. Foster unlocked the door on his side and told the girl to get out her side and run while he held off the three. Foster was knocked unconscious when he left the car. The girl ran into the woods followed by John Giles who caught up with her when she tripped and fell. Petitioner James Giles and Johnson joined them a few minutes later. She testified that, when one of the trio attempted to remove her clothes, she disrobed herself below the waist and submitted to all three youths without resistance because of fear.
  Both petitioners testified in their own defense. Their version of the events was that the three young men approached the car and .asked Foster for a cigarette, that Foster responded with epithets and reached down as if to pick up a gun or other weapon, and that they broke the windows to prevent his getting it. They said that they did not know it was a girl who fled into the woods. Petitioner John Giles testified that when he caught up with her, she offered to submit to him if he would help her escape from the others but that he declined. Petitioner James Giles testified that when he and Johnson joined the couple, the girl told the three that she had had relations with 16 or 17 boys that week and two or three more wouldn’t make any difference, that she disrobed herself and invited all three of them to have relations with her, ahd that he and Johnson, but not petitioner John Giles, had relations with her. Both petitioners testified that the girl said that if they were caught in the woods she would have to say she had been raped because "she was on a year’s probation” and “was in trouble.”
  The credibility of the witnesses was thus important to the outcome of the case. The Court of Appeals recognized this in affirming the convictions on direct review: “There was some evidence tending to indicate consent on the part of the prosecuting witness, which, if believed by the trier of facts, would have been a complete defense to the charge of rape.” Giles v. State, 229 Md., at 381, 183 A. 2d, at 364. Credibility was also critical on the issue whether, in any event, petitioner John Giles had relations with her, as she testified, or had not, as the petitioners testified.
  The evidence allegedly suppressed consisted first, of the fact that in a- proceeding pending on June 20 in the Juvenile Court for Prince George’s County, a caseworker had recommended probation for the girl because she was beyond parental control. Also allegedly suppressed were the facts concerning an occurrence in Prince George’s County at a party on the' night of August 26, 1961, five weeks after the alleged rape, and over three months before the trial. The girl had sexual relations with two men at the party, and later that night took an overdose of pills and was hospitalized in a psychiatric ward of Prince George’s General Hospital for nine days as an attempted suicide. She told a friend who visited her at the hospital that the two men had raped her. The friend told her parents who reported this to Montgomery County Police Lieutenant Whalen, head of the investigation for the State’s Attorney into the charge against petitioners. Lieutenant Whalen advised the mother that he had no jurisdiction of Prince George’s County offenses, after which the girl’s father filed a formal charge of rape against the two men with the Prince George’s County authorities. A Prince George’s County police officer, Sergeant Wheeler, interviewed the girl at the hospital. She refused to say she had. been raped. She told the officer she had previously had relations with one of the men and also that in the previous two years she had had sexual relations with numerous boys and men, some of whom she did not know.
  Finally, the prosecution allegedly suppressed facts concerning a hearing conducted in.the Montgomery County Juvenile Court on September 5, 1961, apparently the day after the girl’s release from her nine-day confinement in the psychiatric ward at Prince George’s General Hospital, and three months before the trial. The hearing resulted in the commitment of the girl to the Montrose School for Girls where she remained for some time. Lieutenant Whalen testified that he had arranged this hearing with the Montgomery County Juvenile Court authorities, although the girl was a resident of Prince George’s County. He testified that the girl’s mother had complained to him that “the boys in Prince George’s County were harassing the girl, driving back and forth past the house all hours,” and that he arranged the .proceeding “to place the girl in some place for protective custody.” The Montgomery Juvenile Court record discloses, however, that the hearing also inquired into the necessity for the girl’s confinement as a juvenile “out of parental control and living in circumstances endangering her well-being.” The girl testified at the hearing that she had taken pills because she felt that “she wanted to die and there was nothing to live for.” 0
  The petitioners’ contention was that all of this evidence tended to support their testimony and discredit that of the girl and Foster and might, therefore, have produced an acquittal or, at least, a reduction of penalty. They also argued that knowledge of it by the defense would have provided valuable leads to evidence supporting a conclusion that the girl testified falsely in denying that she consented to relations.
  The petitioners were represented at the trial by appointed counsel. He testified at the post-conviction proceeding that he knew nothing before the trial of the incidents of August 26, the girl's suicide attempt, her confinement in the hospital, the psychiatrist’s diagnosis of her mental illness, or of her commitment to the Montrose School for Girls. He testified that he had tried, before August 26, to interview the girl at her home but that her mother told him “she talked to Lt. Whalen and he told her not to discuss the case with us.” He also testified, that, based on petitioners’ story to him that the girl had told them she was on probation, he inquired of the Juvenile Courts of both Prince George’s County and Montgomery County whether there were any proceedings in those courts concerning the girl and was told records of such proceedings were not released.
  Judge Moorman found “that the State withheld' from the defense and suppressed both the evidence concerning 'the second rape complaint of the prosecutrix and the evidence relative to her alleged attempted suicide and emotional disturbance.” He ordered a new trial, despite the absence of a pretrial request by defense counsel for disclosure of the evidence suppressed. See Brady v. Maryland, 373 U. S. 83, 87.
  The Court of Appeals read Judge Moorman’s opinion to hold that nondisclosure of evidence by the prosecution denies the accused due process if the evidence could reasonably be considered admissible and useful to the defense. . The Court of Appeals viewed that formulation to be incomplete, holding that “for the nondisclosure of evidence to amount to a denial of due process it must be such as is material and capable of clearing or tending to clear the accused of guilt or of substantially affecting the punishment to be imposed in addition .to being such as could reasonably be considered admissible and useful to the defense.” 239 Md., at 469-470, 212 A. 2d, at 108. The court found the evidence allegedly suppressed did not meet that test and held that in any event “the failure of the prosecution to disclose the information relating to the alleged rape of August 26th and the subsequent suicidal attempt was not prejudicial to . . . [petitioners] and did not therefore warrant the granting of a new trial on the basis of the denial of due process.” 239 Md., at 471, 212 A. 2d, at 109.
  The facts found by Judge Moorman do not include elements present in. earlier decisions which determined that the suppression of evidence constituted the denial of due process of law. See Mooney v. Holohan, 294 U. S. 103; Pyle v. Kansas, 317 U. S. 213; Alcorta v. Texas, 355 U. S. 28; Napue v. Illinois, 360 U. S. 264; Miller v. Pate, ante, p. 1; compare United States ex rel. Almeida v. Baldi, 195 F. 2d 815; United States ex rel. Thompson v. Dye, 221 F. 2d 763; Barbee v. Warden, 331 F. 2d 842. Thus the case presents the broad questions whether the prosecution’s constitutional duty to disclose extends to all evidence admissible and useful to the defense, and the degree of prejudice which must be shown to make necessary a new trial. We find, however, that it 'is unnecessary, and therefore inappropriate, to examine those questions. In Napue v. Illinois, supra, 360 U. S., at 269, we held that a conviction must fall under the Fourteenth Amendment when, the prosecution “although not soliciting false evidence, allows it to go uncorrected when it appears,” even though the testimony may be relevant only to the credibility of a witness. We now have evidence before us, which neither Judge Moor-man nor the Court of Appeals considered, which in our view justifies a remand to the Court of Appeals for its consideration whether that court should order an inquiry to determine whether such a situation arose at petitioners’ trial. The evidence consists of two police - reports, not part of the record, which came to our attention when the State at our request supplied the material considered by the trial judge in imposing sentence.
  On the morning after the alleged rape, July 21, 1961, Montgomery County police officers, including Lieutenant. Whalen and Detective Collins, conducted interviews with the girl and Foster. The interviews were written up in one of the police reports.- In an effort to prove the allegations of the petition, defense counsel moved during the post-conviction proceedings that Lieutenant Whalen be directed to produce the report for inspection. -The motion was denied; Judge Moorman ruled the report was a police “work-product” and therefore not producible under Maryland’s Rules of Procedure.
  There can be little doubt that the defense might have made effective use of the report at -the trial or in obtaining further evidence. In the first place, the report attributes statements to the girl and Poster that appear inconsistent with their trial testimony. The report quotes • both as stating they were engaged in sexual relations when they were distracted by the noise at Bowie’s car, and that the girl dressed before petitioners and Johnson approached. They testified at trial, however, that they were merely “sitting” in the back seat of the car from the time their companions left until their attention was drawn to the presence of the four men at Bowie’s car, and Foster buttressed this testimony on cross-examination by answering “No” to the question whether he “didn’t take her out there to have sexual relations with her, yourself . . . ?” Finally, neither Lieutenant Whalen nor Detective Collins mentioned, in their summaries at trial of what each person involved in the incident had told them, the fact that the girl and Foster had stated they were engaged in sexual relations when they heard the three men.
  The testimony of the girl and Foster is open to the construction that these key witnesses deliberately concealed from the judge, jury, and defense counsel evidence of the girl’s promiscuity. While under the law of Maryland specific acts of misconduct are inadmissible to impeach a witness’ credibility, Rau v. State, 133 Md. 613, 105 A. 867, and specific acts of intercourse are inadmissible to establish the prosecutrix’ consent, Humphreys v. State, 227 Md. 115, 175 A. 2d 777, prior inconsistent statements and evidence of general reputation for un-chastity are admissible to impeach a witness’ credibility, see Giles v. State, 229 Md. 370, 183 A. 2d 359. And to the extent credibility could have been effectively attacked in this case, resolution of the issue, of consent necessarily would have been affected since it turned wholly on credibility.
  >The report could also have been used in connection with an issue which has been in this case from its inception. At the original trial, counsel sought in numerous ways to establish that John Giles had not had intercourse with the victim. At the trial the girl said all three had raped her. She admitted, however, that she had testified at the preliminary hearing and had told the police immediately after being attacked that only two of the three had intercourse with her. Detective Collins testified, on the other hand, that he “questioned the. girl at the station and she said all three of the boys had intercourse with her.” With specific reference to John Giles, Collins stated that the girl “was asked if she knew anybody in this line-up and she walked over and pointed to the defendant, John Giles, and stated to us, in his presence, that he was the first . . . that had intercourse with her . . . .” Lieutenant Whalen denied that the girl had told him “that only two of these boys had intercourse with her on that evening . . . .”
  Counsel at the post-conviction proceedings continued to attempt to prove John Giles was innocent of rape. He introduced newspaper articles from the Washington Evening Star and the Washington Post attributing to Lieutenant Whalen a story that the girl had said only two men had raped her. When Whalen said these stories were incorrect, counsel asked: “would your interview report of this interview show what . . . [she] said about the number of men who attacked her?” Whalen answered that it would. Counsel thereupon moved for the production of the report, but the court refused to allow him to see it because of the work-product rule. Counsel also asked the girl how many men she originally claimed had raped her and, unlike her testimony at trial, she said she had told the police all three had raped her.
  In contrast to much of this testimony the police report states that, both when interviewed and at a police lineup later that day, the girl identified petitioner John Giles not as the first to have intercourse with her, as Detective Collins testified, but as “the one that tried to have intercourse with her but was unable to do so,” “the man that tried to rape her . . . .” The contents of the report thus go, not only to the credibility of the State’s witnesses, but also to the issue at trial whether John Giles had raped the girl. Yet nothing appears in the trial transcript to show what, if any, action was taken by the prosecution to correct or explain the inconsistencies between- the testimony of the state witnesses and the report.
  Only the most strained reading of the materials before us can explain away the questions raised by the report without the aid of further inquiry. A second report, filed by Sergeant Duvall who was first at the scene of the incident, far from proves that John Giles penetrated the girl. His report recites that the girl “stated that two of the . . . males had entered her and that the third had tried but gave up when he saw lights coming.” While this statement would seem to indicate that John Giles, who was the first to attempt intercourse, penetrated the girl, it must be read in light of the fact that Duvall’s report is a two-page, third-person summary, representing what had transpired during the tense and hectic moments immediately after the incident, when the girl was nearly hysterical according to police testimony. The other report, .in contrast, is 22 pages long, was put together over at least a three-day period, and contains extensive quotations of the girl’s story taken down in the relative calm of the police station after the girl had been treated and- fed, including her reaction in personally identifying John Giles as the. one who failed to have intercourse. Moreover, Duvall’s report does state that the girl told him that only two of the men entered her, and therefore provides no explanation for the officers’ testimony that she had said all three had entered her. In fact, far from explaining the police testimony, the report raises a serious question as to the accuracy of Sergeant Duvall’s testimony at the original trial that he never discussed with the girl the number of boys who had had intercourse with her.
  The State attempted in the post-conviction proceedings to explain the girl’s inconsistent statement at the preliminary hearing by contending that she was unaware of the difference between the meaning of intercourse and emission, which caused her to testify at first that only two of the men had had intercourse with her. The state witness who propounded this , theory did not offer it at the original trial, in which he participated, although the girl’s explanation then was that she was confused about the names of the defendants, not about the difference between intercourse and emission. And the report reveals no confusion.on the latter point. She spoke there of intercourse as a “process,” and at one point stated that the second of the youths “had intercourse for about, ten minutes and reached a climax.” She said of John Giles, not that he failed to reach a climax, but, that he failed to “insert” because he “could not get” an erection. Of course it is possible that she was confused despite this evidence, and that John Giles achieved penetration. But it is not our place to decide these issues, either for or against petitioners; we need only determine that the evidence raises an issue of sufficient substance to justify remanding this case for reconsideration rather than deciding the broader constitutional question.
  Original trial counsel testified at the post-conviction proceeding that he had seen the prosecution’s file before trial, including the police reports. Since the reports were not produced, it is pure speculation to conclude that trial counsel had in fact seen the reports now before us. And if it were proper to resolve this question against petitioners, the Court of Appeals might nevertheless regard an inquiry to be in order to ascertain trial counsel’s reasons for not making use of the reports in support of the defense he was directing on behalf of petitioners. Finally, the determination of these questions against petitioners would still leave open the question whether the Court of Appeals might regard the situation as one in which the prosecution was under a duty to disclose the discrepancies to the trial judge; the court stated in its opinion that, where there is doubt as to what should be disclosed, “the trial court should decide whether or not a duty to disclose exists.” 239 Md., at 471, 212 A. 2d, at 109.
  In relying upon material not part of the record as a reason for remand, we follow our practice of noticing supervening matter in order to avoid deciding constitutional questions by allowing state courts to take action which might dispose of the cáse. See for example, Patterson v. Alabama, 294 U. S. 600; Bell v. Maryland, 378 U. S. 226. We follow-this practice under varying circumstances, but the principle behind it has always been the same. This Court has “discretion as to the time and mode in which it will exert the powers conferred upon it. That discretion should be exercised in the light of the relations existing, under- our system of government, between the judicial tribunals of the Union and of the States, and in recognition of the fact that the public good requires that those relations be not disturbed by unnecessary conflict between courts equally bound to guard and protect rights secured by the Constitution.” Ex parte Royall, 117 U. S. 241, 251.
  It is not for us to direct what the Maryland courts will do in this case. The Court of Appeals may, for all we know, determine that the additional evidence demonstrates prejudice to the degree necessary under its previously applied standard to warrant a new trial. It may remand for a hearing free of the “work product” rule. It may reaffirm its judgment of reversal. Although relief may ultimately be denied, affording the state courts the opportunity to decide in the first instance is a course consistent with comity, cf. 28 U. S. C. § 2254, and a full and fair hearing in the state courts would make unnecessary further evidentiary proceedings in the federal courts. See Townsend v. Sain, 372 U. S. 293. We would remand because of our conclusion that the policé’reports, considered in the context of the record before us, raise questions sufficient to justify avoiding decision of the broad constitutional issues presented by affording the opportunity to the Maryland Court of Appeals to decide whether a further hearing should be directed. See Henry v. Mississippi, 379 U. S. 443.
  The truism that our federal system entrusts the States with primary responsibility in the criminal area means more than merely “hands- off.” The States are bound by the Constitution’s relevant commands but they are not limited by them. We therefore should not operate upon the assumption — especially inappropriate in Maryland’s case in light of its demonstrated concern to afford post-conviction relief paralleling that which may be afforded by federal courts in habeas corpus proceedings— that state courts would not be concerned to reconsider a case in light of evidence such as we have here, particu,larly where the result may avoid unnecessary constitutional adjudication and minimize federal-state tensions.
  We would therefore vacate' the judgment of the Court of Appeals and remand to that court for further proceedings.
  Petitioners had previously appealed unsuccessfully from the convictions, Giles v. State, 229 Md. 370, 183 A. 2d 359, appeal dismissed, 372 U. S. 767, and from the denial of a new trial, Giles v. State, 231 Md. 387, 190 A. 2d 627.
  Johnson was tried and convieted of rape of the girl at a separate trial in the Circuit Court for Anne Arundel County. His application for post-conviction relief is being held in abeyance pending disposition of this case.
  “With respect to the presence or absence of the element of consent, it is true, of course, that however reluctantly given, consent to the act at any time prior to penetration deprives the subsequent intercourse of its criminal character.” Hazel v. State, 221 Md. 464, 469, 157 A. 2d 922, 925.
  If the jury which finds an accused guilty of rape adds to its verdict the words “without capital punishment,” the court may not impose the death penalty but only imprisonment for not exceeding 20 years in the penitentiary. Md. Ann. Code Art. 27, §463 (1957). If the jury does not add such words to its verdiot, the court, at its discretion; may impose the death sentence, a life sentence, or a sentence in the penitentiary for not less than 18 months nor more, than 21 years. Md. Ann. Code Art. 27, §461 (1957). The jury did not add to its verdict the words “without capital punishment,” and the trial judge imposed death sentences. Governor Tawes subsequently commuted the sentences to life imprisonment.
  Other counsel are representing them in the post-conviction proceedings.
  The dissenting judges in the Court of Appeals were of the view that the extensive evidence of the girl’s reputation for unchastity presented in the post-conviction record, added to the evidence of her emotional instability, might support a defense that she suffered from an uncontrollable weakness that petitioners might reasonably have mistaken for consent. The majority apparently were also of the view that under some circumstances suppression of evidence pertaining to a witness’ mental condition might amount to a deprivation of due process. If this is so, the conclusion of the majority that no such evidence existed or was suppressed in this case is open to question, since the post-conviction court prevented all attempts of counsel to introduce evidence of the girl’s condition (including a psychiatric diagnosis and evidence presented at a juvenile proceeding) or of the fact that Montgomery County police officials knew of such evidence. If a new hearing is held in the state courts, an inquiry into these matters might be deemed appropriate.
  The record before us affirmatively demonstrates that both Detective Collins and Mr. Kardy, who supervised the prosecution, had read the report before trial. Collins testified at the trial that he wrote up the report and had read it the night before. At the post-conviction hearing Kardy was asked: “[Yjou saw the police report prior to trial, of course? A. Yes.”
  The testimony was as follows:
  “Q. Did you have a discussion with this girl about how many boys had had intercourse with her? . . .
  “A. No.
  “Q. You say you did not?
  "A. No, sir.
  “Q. You never did discuss that with her?
  “A. No, sir.”
  “Q. Why are you telling a different story today than the story you told the police immediately after this happened, and the story you told at the preliminary hearing?
  “A. Because I have thought about it.
  ••“Q. What do you mean you have thought about it?
  “A. Well at the time I was confused — people were giving names, and I had no idea of what the boys’ names were.
  “Q. Who was given names?
  “A. After the line-ups; after I had identified all three of the men.”
  The report recites that she was asked the following questions, apparently by Lieutenant Whalen, and gave the following answers:
  “Q-W. How many of them had intercourse with you?
  “A. The bigger one [John] tried first, then the other two.
  “Q-W. Did any of them have an emission?
  “A. Yes, the second one and maybe the third.”
  Certainly the test cannot 'be, as is suggested, that a remand would be justified only if the evidence presented “necessarily excludes the conclusion that John Giles achieved penetration, however slight.”
  See Hunt v. Warden, 335 F. 2d 936, 941-943 (C. A. 4th Cir., 1964); Midgett v. Warden, 329 F. 2d 185 (C. A. 4th Cir., 1964), and the other cases discussed in Note, 40 N. Y. U. L. Rev. 154, 193-195 (1965).
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