opinion: SMITH, CORRECTIONAL SUPERINTENDENT v. PHILLIPS
  No. 80-1082.
  Argued November 9, 1981
  Decided January 25, 1982
  Rehnquist, J., delivered the opinion of the Court, in which Burger, C. J., and White, Blackmun, Powell, and O’Connor, JJ., joined. O’Connor, J., filed a concurring opinion, post, p. 221. Marshall, J., filed a dissenting opinion, in which Brennan and Stevens, JJ., joined, post, p. 224.
  Robert M. Pitler argued the cause for petitioner. With him on the briefs were Mark Dwyer and Vivian Berger.
  William M. Kunstler argued the cause for respondent. With him on the briefs was C. Vernon Mason.
  Charies S. Sims, Bruce J. Ennis, Jr., and Richard M. Zuckerman filed a brief for the American Civil Liberties Union et al. as amici curiae urging affirmance.
  Justice Rehnquist
  delivered the opinion of the Court.
  Respondent was convicted in November 1974 by a New York state-court jury on two counts of murder and one count of attempted murder. After trial, respondent moved to vacate his conviction pursuant to §330.30 of the N.Y. Crim. Proc. Law (McKinney 1971) (CPL), and a hearing on his motion was held pursuant to CPL §330.40. The hearing was held before the justice who presided at respondent’s trial, and the motion to vacate was denied by him in an opinion concluding “beyond a reasonable doubt” that the events giving rise to the motion did not influence the verdict. People v. Phillips, 87 Misc. 2d 613, 614, 630, 384 N. Y. S. 2d 906, 907-908, 918 (1975). The Appellate Division of the Supreme Court, First Judicial Department, affirmed the conviction without opinion. 52 App. Div. 2d 758, 384 N. Y. S. 2d 715 (1976). The New York Court of Appeals denied leave to appeal. 39 N. Y. 2d 949, 352 N. E. 2d 894 (1976).
  Some four years after the denial of leave to appeal by the Court of Appeals, respondent sought federal habeas relief in the United States District Court for the Southern District of New York on the same ground which had been asserted in the state post-trial hearing. The District Court granted the writ, 485 F. Supp. 1365 (1980), and the United States Court of Appeals for the Second Circuit affirmed on a somewhat different ground. 632 F. 2d 1019 (1980). We granted certio-rari to consider the important questions of federal constitutional law in relation to federal habeas proceedings raised by these decisions. 450 U. S. 909 (1981). We now reverse.
  I
  A
  Respondent’s original motion to vacate his conviction was based on the fact that a juror in respondent’s case, one John Dana Smith, submitted during the trial an application for employment as a major felony investigator in the District Attorney’s Office. Smith had learned of the position from a friend who had contacts within the office and who had inquired on Smith’s behalf without mentioning Smith’s name or the fact that he was a juror in respondent’s trial. When Smith’s application was received by the office, his name was placed on a list of applicants but he was not then contacted and was not known by the office to be a juror in respondent’s trial.
  During later inquiry about the status of Smith’s application, the friend mentioned that Smith was a juror in respondent’s case. The attorney to whom the friend disclosed this fact promptly informed his superior, and his superior in turn informed the Assistant District Attorney in charge of hiring investigators. The following day, more than one week before the end of respondent’s trial, the assistant informed the two attorneys actually prosecuting respondent that one of the jurors had applied to the office for employment as an investigator.
  The two prosecuting attorneys conferred about the application but concluded that, in view of Smith’s statements during voir dire, there was no need to inform the trial court or defense counsel of the application. They did instruct attorneys in the office not to contact Smith until after the trial had ended, and took steps to insure that they would learn no information about Smith that had not been revealed during voir dire. When the jury retired to deliberate on November 20th, three alternate jurors were available to substitute for Smith, and neither the trial court nor the defense counsel knew of his application. The jury returned its verdict on November 21st.
  The District Attorney first learned of Smith’s application on December 4th. Five days later, after an investigation to verify the information, he informed the trial court and defense counsel of the application and the fact that its existence was known to attorneys in his office at some time before the conclusion of the trial. Respondent’s attorney then moved to set aside the verdict.
  At the hearing before the trial judge, Justice Harold Birns, the prosecuting attorneys explained their decision not to disclose the application and Smith explained that he had seen nothing improper in submitting the application during the trial. Justice Bims, “[f]rom all the evidence adduced” at the hearing, 87 Mise. 2d, at 621, 384 N. Y. S. 2d, at 912, found that “Smith’s letter was indeed an indiscretion” but that it “in no way reflected a premature conclusion as to the [respondent’s] guilt, or prejudice against the [respondent], or an inability to consider the guilt or innocence of the [respondent] solely on the evidence.” Id., at 627, 384 N. Y. S. 2d, at 915. With respect to the conduct of the prosecuting attorneys, Justice Birns found “no evidence” suggesting “a sinister or dishonest motive with respect to Mr. Smith’s letter of application.” Id., at 618-619, 384 N. Y. S. 2d, at 910.
  B
  In his application for federal habeas relief, respondent contended that he had been denied due process of law under the Fourteenth Amendment to the United States Constitution by Smith’s conduct. The District Court found insufficient evidence to demonstrate that Smith was actually biased. 485 F. Supp., at 1371. Nonetheless, the court imputed bias to Smith because “the average man in Smith’s position would believe that the verdict of the jury would directly affect the evaluation of his job application.” Id., at 1371-1372. Accordingly, the court ordered respondent released unless the State granted him a new trial within 90 days.
  The United States Court of Appeals for the Second Circuit affirmed by a divided vote. The court noted that “it is at best difficult and perhaps impossible to learn from a juror’s own testimony after the verdict whether he was in fact ‘impartial,’” but the court did not consider whether Smith was actually or impliedly biased. 632 F. 2d, at 1022. Rather, the Court of Appeals affirmed respondent’s release simply because “the failure of the prosecutors to disclose their knowledge denied [respondent] due process.” Ibid. The court explained: “To condone the withholding by the prosecutor of information casting substantial doubt as to the impartiality of a juror, such as the fact that he has applied to the prosecutor for employment, would not be fair to a defendant and would ill serve to maintain public confidence in the judicial process.” Id., at 1023.
  II
  In argument before this Court, respondent has relied primarily on reasoning adopted by the District Court. He contends that a court cannot possibly ascertain the impartiality of a juror by relying solely upon the testimony of the juror in question. Given the human propensity for self-justification, respondent argues, the law must impute bias to jurors in Smith’s position. We disagree.
  This Court has long held that the remedy for allegations of juror partiality is a hearing in which the defendant has the opportunity to prove actual bias. For example, in Remmer v. United States, 347 U. S. 227 (1954), a juror in a federal criminal trial was approached by someone offering money in exchange for a favorable verdict. An FBI agent was assigned to investigate the attempted bribe, and the agent’s report was reviewed by the trial judge and the prosecutor without disclosure to defense counsel. When they learned of the incident after trial, the defense attorneys moved that the verdict be vacated, alleging that “they would have moved for a mistrial and requested that the juror in question be replaced by an alternate juror” had the incident been disclosed to them during trial. Id., at 229.
  This Court recognized the seriousness not only of the attempted bribe, which it characterized as “presumptively prejudicial,” but also of the undisclosed investigation, which was “bound to impress the juror and [was] very apt to do so unduly.” Ibid. Despite this recognition, and a conviction that “[t]he integrity of jury proceedings must not be jeopardized by unauthorized invasions,” ibid., the Court did not require a new trial like that ordered in this case. Rather, the Court instructed the trial judge to “determine the circumstances, the impact thereof upon the juror, and whether or not [they were] prejudicial, in a hearing with all interested parties permitted to participate.” Id., at 230 (emphasis added). In other words, the Court ordered precisely the remedy which was accorded by Justice Bims in this case.
  Even before the decision in Remmer, this Court confronted allegations of implied juror bias in Dennis v. United States, 339 U. S. 162 (1950). Dennis was convicted of criminal contempt for failure to appear before the Committee on Un-American Activities of the House of Representatives. He argued that the jury which convicted him, composed primarily of employees of the United States Government, was inherently biased because such employees were subject to Executive Order No. 9835, 3 CFR 627 (1943-1948 Comp.), which provided for their discharge upon reasonable grounds for belief that they were disloyal to the Government. Dennis contended that such employees would not risk the charge of disloyalty or the termination of their employment which might result from a vote for acquittal. The Court rejected this claim of implied bias, noting that Dennis was “free to show the existence of actual bias” but had failed to do so. 339 U. S., at 167. The Court thus concluded: “A holding of implied bias to disqualify jurors because of their relationship with the Government is no longer permissible. . . . Preservation of the opportunity to prove actual bias is a guarantee of a defendant’s right to an impartial jury.” Id., at 171-172. See also Frazier v. United States, 335 U. S. 497 (1948); United States v. Wood, 299 U. S. 123 (1936).
  Our decision last Term in Chandler v. Florida, 449 U. S. 560 (1981), also treated a claim of implied juror bias. Appellants in Chandler were convicted of various theft crimes at a jury trial which was partially televised under a new Canon of Judicial Ethics promulgated by the Florida Supreme Court. They claimed that the unusual publicity and sensational courtroom atmosphere created by televising the proceedings would influence the jurors and preclude a fair trial. Consistent with our previous decisions, we held that “the appropriate safeguard against such prejudice is the defendant’s right to demonstrate that the media’s coverage of his case — be it printed or broadcast — compromised the ability of the particular jury that heard the case to adjudicate fairly. ” Id., at 575. Because the appellants did “not [attempt] to show with any specificity that the presence of cameras impaired' the ability of the jurors to decide the case on only the evidence before them,” we refused to set aside their conviction. Id., at 581.
  These cases demonstrate that due process does not require a new trial every time a juror has been placed in a potentially compromising situation. Were that the rule, few trials would be constitutionally acceptable. The safeguards of juror impartiality, such as voir dire and protective instructions from the trial judge, are not infallible; it is virtually impossible to shield jurors from every contact or influence that might theoretically affect their vote. Due process means a jury capable and willing to decide the case solely on the evidence before it, and a trial judge ever watchful to prevent prejudicial occurrences and to determine the effect of such occurrences when they happen. Such determinations may properly be made at a hearing like that ordered in Remmer and held in this case.
  The District Court and the Court of Appeals disregarded this doctrine: they held that a post-trial hearing comporting with our decisions in Remmer and other cases prosecuted in the federal courts was constitutionally insufficient in a state court under the Due Process Clause of the Fourteenth Amendment. It seems to us to follow “as the night the day” that if in the federal system a post-trial hearing such as that conducted here is sufficient to decide allegations of juror partiality, the Due Process Clause of the Fourteenth Amendment cannot possibly require more of a state court system.
  Of equal importance, this case is a federal habeas action in which Justice Birns’ findings are presumptively correct under 28 U. S. C. § 2254 (d). We held last Term that federal courts in such proceedings must not disturb the findings of state courts unless the federal habeas court articulates some basis for disarming such findings of the statutory.presumption that they are correct and may be overcome only by convincing evidence. Sumner v. Mata, 449 U. S. 539, 551 (1981). Here neither the District Court nor the Court of Appeals took issue with the findings of Justice Bims.
  Ill
  As already noted, the Court of Appeals did not rely upon the District Court’s imputation of bias. Indeed, it did not even reach the question of juror bias, holding instead that the prosecutors’ failure to disclose Smith’s application, without more, violated respondent’s right to due process of law. Respondent contends that the Court of Appeals thereby correctly preserved “the appearance of justice.” Brief for Respondent 7. This contention, too, runs contrary to our decided cases.
  Past decisions of this Court demonstrate that the touchstone of due process analysis in cases of alleged prosecutorial misconduct is the fairness of the trial, not the culpability of the prosecutor. In Brady v. Maryland, 373 U. S. 83 (1963), for example, the prosecutor failed to disclose an admission by a participant in the murder which corroborated the defendant’s version of the crime. The Court held that a prosecutor’s suppression of requested evidence “violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution.” Id., at 87. Applying this standard, the Court found the undisclosed admission to be relevant to punishment and thus ordered that the defendant be resentenced. Since the admission was not material to guilt, however, the Court concluded that the trial itself complied with the requirements of due process despite the prosecutor’s wrongful suppression. The Court thus recognized that the aim of due process “is not punishment of society for the misdeeds of the prosecutor but avoidance of an unfair trial to the accused.” Ibid.
  This principle was reaffirmed in United States v. Agurs, 427 U. S. 97 (1976). There, we held that a prosecutor must disclose unrequested evidence which would create a reasonable doubt of guilt that did not otherwise exist. Consistent with Brady, we focused not upon the prosecutor’s failure to disclose, but upon the effect of nondisclosure on the trial:
  “Nor do we believe the constitutional obligation [to disclose unrequested information] is measured by the moral culpability, or willfulness, of the prosecutor. If evidence highly probative of innocence is in his file, he should be presumed to recognize its significance even if he has actually overlooked it. Conversely, if evidence actually has no probative significance at all, no purpose would be served by requiring a new trial simply because an inept prosecutor incorrectly believed he was suppressing a fact that would be vital to the defense. If the suppression of the evidence results in constitutional error, it is because of the character of the evidence, not the character of the prosecutor.” 427 U. S., at 110 (footnote and citation omitted).
  In light of this principle, it is evident that the Court of Appeals erred when it concluded that prosecutorial misconduct alone requires a new trial. We do not condone the conduct of the prosecutors in this case. Nonetheless, as demonstrated in Part II of this opinion, Smith’s conduct did not impair his ability to render an impartial verdict. The trial judge expressly so found. 87 Mise. 2d, at 627, 384 N. Y. S. 2d, at 915.
  Therefore, the prosecutors’ failure to disclose Smith’s job application, although requiring a post-trial hearing on juror bias, did not deprive respondent of the fair trial guaranteed by the Due Process Clause.
  > h-H
  A federally issued writ of habeas corpus, of course, reaches only convictions obtained in violation of some provision of the United States Constitution. As we said in Cupp v. Naughten, 414 U. S. 141, 146 (1973):
  “Before a federal court may overturn a conviction resulting from a state trial ... it must be established not merely that the [State’s action] is undesirable, erroneous, or even ‘universally condemned,’ but that it violated some right which was guaranteed to the defendant by the Fourteenth Amendment.”
  Absent such a constitutional violation, it was error for the lower courts in this case to order a new trial. Even if the Court of Appeals believed, as the respondent contends, that prosecutorial misbehavior would “reign unchecked” unless a new trial was ordered, it had no authority to act as it did. Federal courts hold no supervisory authority over state judicial proceedings and may intervene only to correct wrongs of constitutional dimension. Chandler v. Florida, 449 U. S., at 570, 582-583; Cupp v. Naughten, supra, at 146. No such wrongs occurred here. Accordingly, the judgment of the Court of Appeals is
  Reversed.
  Section 330.30 provides in pertinent part:
  “At any time after rendition of a verdict of guilty and before sentence, the court may, upon motion of the defendant, set aside or modify the verdict or any part thereof upon the following grounds:
  “2. That during the trial there occurred, out of the presence of the court, improper conduct by a juror, or improper conduct by another person in relation to a juror, which may have affected a substantial right of the defendant and which was not known to the defendant prior to the rendition of the verdict. . . .”
  CPL § 330.40 provides that motions to set aside the verdict under CPL § 330.30 must be decided by hearing if they allege disputed facts sufficient to grant the motion. At the hearing, “the defendant has the burden of proving by a preponderance of the evidence every fact essential to support the motion.” CPL § 330.40(g).
  Smith’s letter of application was addressed to the District Attorney and stated:
  “I understand that a federally funded investigative unit is being formed in your office to investigate major felonies. I wish to apply for a position as an investigator.”
  The letter did not mention that Smith was a juror in respondent’s trial. Appended to the letter was a resumé containing biographical information about Smith. People v. Phillips, 87 Misc. 2d 613, 616, 384 N. Y. S. 2d 906, 909 (1975).
  The trial judge described the voir dire in respondent’s case as “ten days of meticulous examination.” Id., at 614, 384 N. Y. S. 2d, at 907. During his voir dire, Smith stated that he intended to pursue a career in law enforcement and that he had applied for employment with a federal drug enforcement agency. He also disclosed that his wife was interested in law enforcement, an interest which arose out of an incident in which she was assaulted and seriously injured. Smith stated that he had previously worked as a store detective for Bloomingdale’s Department Store, and, in that capacity, had made several arrests which led to contact with the District Attorney’s Office. In response to close inquiry by defense counsel, Smith declared his belief that he could be a fair and impartial juror in the case. This assurance apparently satisfied defense counsel, for Smith was permitted to take his seat among the jurors even though the defense had several unused peremptory challenges.
  This conclusion was based upon the majority’s reading of our decision in United States v. Agurs, 427 U. S. 97 (1976), a reading by which it concluded that due process is violated when the prosecutor’s actions treat a defendant unfairly or impugn the integrity of the judicial process, even if the defendant is not thereby prejudiced. 632 F. 2d 1019,1023 (1980). As will be seen in Part III of this opinion, the Court of Appeals misread Agio's.
  Respondent may, of course, defend the judgment below on any ground which the law and the record permit, provided the asserted ground would not expand the relief which has been granted. United States v. New York Telephone Co., 434 U. S. 159, 166, n. 8 (1977); Dandridge v. Williams, 397 U. S. 471, 475, n. 6 (1970); Ryerson v. United States, 312 U. S. 405, 408 (1941).
  Respondent correctly notes that determinations made in Remmer-type hearings will frequently turn upon testimony of the juror in question, but errs in contending that such evidence is inherently suspect. As we said in Dennis v. United States, 339 U. S. 162 (1950), “[o]ne may not know or altogether understand the imponderables which cause one to think what he thinks, but surely one who is trying as an honest man to live up to the sanctity of his oath is well qualified to say whether he has an unbiased mind in a certain matter.” Id., at 171. See also United States v. Reid, 12 How. 361, 366 (1852).
  Tn connection with his argument that due process was denied by the prosecutors’ withholding of Smith’s application, respondent notes that had the prosecutors disclosed the application, the trial court could have replaced Smith with an alternate juror. Thus, respondent argues, not only was the prosecutors’ action itself a denial of due process, but it also prevented respondent from availing himself of the process available under New York law for correcting juror bias. See N. Y. CPL § 270.35 (McKinney 1971). This argument proves too much. If the hearing and determination to replace a juror during trial would have adequately protected respondent’s right to due process of law, and would not have been rendered impossible by necessary reliance on the juror’s own testimony, we see no reason why a post-trial hearing and determination would be any less protective or possible.
  As we said of Brady in United States v. Agurs, 427 U. S., at 106: “[T]he confession could not have affected the outcome on the issue of guilt but could have affected Brady’s punishment. It was material on the latter issue but not on the former. And since it was not material on the issue of guilt, the entire trial was not lacking in due process.”
  Even in cases of egregious prosecutorial misconduct, such as the knowing use of perjured testimony, we have required a new trial only when the tainted evidence was material to the case. See Giglio v. United States, 405 U. S. 150, 154 (1972); Napue v. Illinois, 360 U. S. 264, 272 (1959). This materiality requirement implicitly recognizes that the misconduct’s effect on the trial, not the blameworthiness of the prosecutor, is the crucial inquiry for due process purposes.
  We note, of course, that nothing in this case suggests that the prosecutors’ conduct was undertaken in bad faith. As the trial court found, “there is no evidence which to any degree points to a conclusion that any member of the District Attorney’s staff, ... or any court officer, had a sinister or dishonest motive with respect to Mr. Smith’s letter of application, or sought to gain thereby an unfair advantage over the defendant.” 87 Mise. 2d, at 618-619, 384 N. Y. S. 2d, at 910.