After we affirmed Levin’s grand larceny conviction,1 he filed a petition for habeas corpus alleging that the prosecutor did not reveal evidence which would have been helpful. The District Court denied the petition, but we reversed and remanded so that the District Court could determine whether “the government failed to disclose evidence which * * * might have led the jury to entertain a reasonable doubt about appellant’s guilt. Such a failure may be classified as negligence.”2 Levin is now appealing from the District Court’s finding, on remand, that the evidence would not have led the jury to doubt his guilt.3
The prosecutor’s constitutional duty to reveal evidence to the defendant was recognized in Mooney v. Holohan4 and Pyle v. State of Kansas.5 In Pyle, the Supreme Court said:
Petitioner’s papers * * * set forth allegations that his imprisonment resulted from perjured testimony, knowingly used by the State authorities to obtain his conviction, and from the deliberate suppression by those same authorities of evidence favorable to him. These allegations sufficiently *1211charge a deprivation of rights guaranteed by the Federal Constitution, and, if proven, would entitle petitioner to release from his present custody.6
From these cases two lines of decision emerged. The first line involved cases in which the prosecutor suborned perjury or knowingly used perjured testimony at trial.7 The rationale of these cases seems to have been that convictions must not be obtained through pros-ecutorial misconduct which violates civilized notions of fairness and thereby taints the entire criminal process. Lawless law enforcement should not be tolerated.8
The second line of decisions, which involved the duty to reveal evidence, had the same beginning as the first. In early cases, the suppression was so clearly unfair that it tainted the criminal process as much as if the prosecutor had suborned perjury.
The methods employed by the prosecution * * * [represent] as shocking a situation as ever before presented before this court. A society cánnot suppress lawlessness by an accused through the means of lawlessness of the prosecution. A society cannot inspire respect for the law by withholding its protection from those accused of crimes.9
Soon, however, the courts began to recognize that even negligent suppression, though it was not “shocking” or “lawless,” could violate the constitution.10 In Brady v. State of Maryland.11 the Supreme Court confirmed this development.
We now hold that the suppression by the prosecution of evidence favorable to an accused upon request 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.12
As the focus of the cases shifted away from the prosecutor’s misconduct, of necessity the constitutional rationale changed also. If the prosecutor acted in good faith and was merely negligent, he did not taint the criminal process. The new rationale focused not on misconduct of the prosecutor but on harm to the defendant. The Government’s facilities for discovering evidence are usually far superior to the defendant’s. This imbalance is a weakness in our adversary system which increases the possibility of erroneous convictions. When the Government aggravates the imbalance by failing to reveal evidence which would be helpful to the defendant the constitution has been violated.13 The concern is not that law enforcers are breaking the *1212law but that innocent people may be convicted.
The question is what kinds of evidence must the prosecutor reveal? Various courts have talked about “favorable” evidence,14 “material” evidence,15 “pertinent facts relating to [the] defense,” 16 “information impinging on a vital area in [the] defense,” 17 evidence vital “to the accused persons in planning and conducting their defense,”18 and “evidence that may reasonably be considered admissible and useful to the defense. When there is substantial room for doubt, the prosecution is not to decide for the court what is admissible or for the defense what is useful.”19 Without excluding any of these relevant considerations, in the present case we focused upon the ultimate possibility of harm to the defendant — the possibility of erroneous conviction — and we stated the standard in terms of whether the evidence “might have led the jury to entertain a reasonable doubt about [defendant’s] guilt.” 20
This standard requires speculation because there is no sure way to know how the jury would have viewed any particular piece of evidence. Nor is it possible to know whether revelation of the evidence would have changed the configuration of the trial — whether defense counsel’s preparation would have been different had he known about the evidence, whether new defenses would have been added, whether the emphasis of the old defenses would have shifted.21 Because the standard requires this kind of speculation we cannot apply it harshly or dogmatically. In Griffin v. United States,22 the Supreme Court directed us to consider “whether it would not be too dogmatic, on the basis of mere speculation, for any court to conclude that the jury would not have attached significance to the evidence favorable to the defendant had the evidence been before it.”23 We think it would be too dogmatic here.24
*1213Levin was convicted on one count of grand larceny. The indictment charged that on or about February 13, 1959, he stole $35,000 from the Bakery and Confectionery Workers International Union of America. The money was supposed to have been embezzled by various members of the Union and given to Levin on or about the 13th of February so that he could fix the pending perjury trial of James Cross, the President of the Union. Levin was supposed to have taken the money without performing the services.
The Government’s brief describes a strong case against Levin. James Lan-driscina, Vice President of the Union, provided most of the background. He testified that he met Levin in January, 1959. Levin said he could fix Cross’s case for $35,000 or $40,000. Landriscina arranged for Levin to meet Cross in Washington. To pay for the trip, Levin received a check for $600. Landriscina was present at two meetings between Levin and Cross at which the price for the fix was set at $35,000. Levin also requested that he be hired by the Union as general counsel. After some dispute, Cross agreed to hire Levin as a lobbyist for $17,500 a year.
During both days of the Cross trial, February 16 and 17, Landriscina saw Levin standing around the corner from the courtroom. After the trial, Levin submitted a bill for “Professional services rendered through February 28, 1959, $17,500,” but he received no money. On April 8, 1959, Landriscina made partial payment of $2,500 from the funds of his local union. Ultimately the Union did pay Levin more than $17,500 during 1959. The Government exhibits documented payments to Levin in 1959 of $600, $2,500, $2,500 and $15,000. Also, it was shown that Levin performed almost no services for the Union in 1959.
The Government’s evidence outlined above may have shown that Levin was engaged in some shady dealings with the Union. But he was not tried for, or convicted of, fixing or attempting to fix a perjury case. Nor was he convicted of fraudulently representing himself to the Union as a lobbyist. He was convicted of stealing $35,000 from the Union on or about February 13, 1959. The evidence outlined above serves only to set the background and show the circumstances of the alleged larceny.
Landriscina was the only witness to the larceny itself. He gave a very detailed account of the transaction. He testified to the following: On Tuesday, February 10, Levin asked Landriscina for $10,000. Levin said he needed the money to pay some jurors and court attendants. On Thursday, February 12, Landriscina received an envelope with $1,000 bills from Olson, Secretary-Treasurer of the Union, and at 11:00 a. m. handed it to Levin on a park bench. At 12:00 Levin met Lan-driscina again and said that the $1,000 bills must be changed into smaller bills. Landriscina took the $1,000 bills, returned to his office, had someone exchange the $1,000 bills for smaller bills, and returned the smaller bills to Levin. The next day, Friday, February 13, Landris-cina gave Lavin $25,000, the balance of the promised $35,000, in small bills.
Peter Olson and Richard Ashby told a different story. Olson testified that on Friday, February 13, he cashed a $35,000 check at the National Savings and Trust Company and received the money in $1,-000 bills.25 At 10:45 a. m. he gave ten $1,000 bills to Landriscina.
It was Ashby who supposedly exchanged the $1,000 bills for $20 bills at the bank. He testified that he was in the Union’s office on Friday, February 13, when Olson returned from the bank with thirty-five $1,000 bills.26 He saw Olson give ten of the bills to Landriscina. Olson left the other twenty-five $1,000 bills with Ashby. Later Landriscina returned *1214to the Union’s office and asked Ashby to exchange the entire $35,000. Ashby went to the bank, dealt with a Mr. McCeney,27 exchanged the bills, and returned in a few minutes.
The two pieces of evidence which the Government failed to reveal bear directly upon this complicated transaction. The first was a check for $35,000, dated February 13, 1959, drawn on the Riggs National Bank by the National Savings & Trust Co. to enable National Savings to replace the thirty-five $1,000 bills which Olson withdrew. The argument is that it would not have been necessary to replenish the supply of $1,000 bills if they were returned. But, as we pointed out in our previous opinion, the bank’s practice was to replenish the supply as soon as possible after a withdrawal, so National’s check on Riggs might have been issued even if the $1,000 bills were after-wards returned.
The second piece of evidence is more significant. The Government had in its possession a statement by Mr. Mc-Ceney, the bank officer with whom Ash-by dealt when he exchanged the $1,000 bills.
I hereby recall Mr. Olson coming in with a $35,000 check, dated February 13, 1959 to be cashed but I do not recall a telephone call from Mr. Olson to arrange the cashing of this cheek. Mr. Olson came in and I took him to Mr. Hooper, who, at that time, was running one of the savings windows and handling the large cash, to cash this check which he did in thousand dollar bills. I do not recall Mr. Ashby coming in to change the thousand dollar bills to smaller ones. If he did I would have taken him back to Mr. Hooper because he was handling the large bills. Mr. Hooper says he does not recall cashing this money into smaller bills that day.
Ashby specifically testified before the Grand Jury that he dealt with Mr. Mc-Ceney when he exchanged the bills. Yet McCeney said that he did not remember the exchange, although he did remember Olson’s cashing a $35,000 cheek earlier that same day.28 Also, McCeney claimed that if he had been asked to exchange thirty-five $1,000 bills he would have gone directly to Mr. Hooper. According to the statement which was not revealed, Hooper did not remember cashing the money into smaller bills either.29
*1215If the jury had known of McCeney’s statement and had taken it to indicate that there was no exchange into smaller bills, then Landriseina’s description of the transaction would have fallen and with it the heart of the Government’s case. Of course the jury might have disbelieved McCeney, or it might have decided that the exchange took place even though McCeney and Hooper did not remember it.30 Or the jury might have convicted on the basis of the circumstantial evidence even though it believed that the exchange of bills and the transaction surrounding that exchange had not occurred. Yet it is clearly within the realm of possibility that the jury would have “attached significance”31 to McCeney’s statement.32
We would be required to reverse, then, even if the statement’s only significance were in the way a jury might have viewed it. However, the statement has another importance. With knowledge of McCeney’s statement, defense counsel certainly would have probed deeper into what was the central aspect of the Government’s case. For example, with some investigation, reconstruction of events, and discussions with Hooper and McCen-ey, defense counsel might have been able to transform their inability to remember the transaction into a positive statement that there was no exchange of bills.
In fact, at the habeas corpus hearing after the trial Hooper testified that to the best of his knowledge he had not exchanged the bills.
Mr. Olson contacted one of our officers, Assistant Treasurer, Mr. Mc-Ceney, and asked him to cash this $35,-000 check, which I had the thousand dollar bills. We usually maintained a certain level, say around $50,000 in thousand dollar bills for these special requests. So I cashed this check and that is the last I saw of the transaction. Now, to my knowledge, that was the end of the transaction as far as I was concerned.
Apparently Olson’s visit to the bank was the end of the transaction as far as Mc-Ceney was concerned also. Before the habeas corpus hearing he told petitioner’s counsel that
To the best of [my] knowledge, these $1000 bills were never returned that day (or any reasonable time thereafter) for exchange into currency of smaller denominations.
At the hearing McCeney confirmed his statement
[T]hat is the knowledge that I have of it, that they never, they were not returned shortly or at any later date, the $1000 bills.
This testimony would have had great significance if it were brought out at trial because Ashby said he dealt with McCeney, and McCeney said if anyone had come to him to make the exchange, he would have gone directly to Hooper. So both McCeney and Hooper would have known of the exchange had it occurred. Of course, their subsequent testimony was not known to the prosecutor before trial, and we do not hold him responsible for not discovering and revealing it. However, its fortuitous discovery at the habeas corpus hearing adds credence to our speculation that, if defense counsel knew of McCeney’s pre-trial statement, the course of the trial might have been quite different.
Reversed for a new trial.
. Levin v. United States, 119 U.S.App.D.C. 156, 338 F.2d 265 (1964), cert. denied 379 U.S. 999, 85 S.Ct. 719, 13 L.Ed.2d 701 (1965).
. Levin v. Katzenbach, 124 U.S.App.D.C. 158, 162, 363 F.2d 287, 291 (1966).
. Levin v. Katzenbach, 262 F.Supp. 951 (1966).
. 294 U.S. 103, 55 S.Ct. 340, 79 L.Ed. 791 (1935).
. 317 U.S. 213, 63 S.Ct. 177, 87 L.Ed. 214 (1942).
. 317 U.S. at 215-216, 63 S.Ct. at 178.
. Alcorta v. State of Texas, 355 U.S. 28, 78 S.Ct. 103, 2 L.Ed.2d 9 (1957), Napue v. State of Illinois, 360 U.S. 264, 79 S.Ct. 1173, 3 L.Ed.2d 1217 (1959).
. People v. Savvides, 1 N.Y.2d 554, 556-557, 154 N.Y.S.2d 885, 887, 136 N.E.2d 853, 854 (1956) ; Note, The Prosecutor’s Constitutional Duty to Reveal Evidence to the Defendant, 74 Yale L.J. 136, 137-139 (1964). The dissenting judge has already indicated agreement with our analysis of this line of cases.
Presentation of perjured testimony and deliberate suppression of evidence are types of conduct which not only prejudice the defendant but also violate the law, the basic duty of the prosecutor as an officer of the Court, and the very integrity of the judicial process. Such conduct is impermissible. As a result, a showing that the prosecution knowingly suppressed revelant exculpatory evidence automatically entitles the defendant to a new trial, with little or no showing of prejudice. Levin v. Katzenbach, 124 U.S.App.D.C. at 165, 363 F.2d at 294 (dissenting opinion).
. United States ex rel. Montgomery v. Ragan, 86 F.Supp. 382, 387 (N.D.Ill. 1949).
. United States ex rel. Thompson v. Dye, 221 F.2d 763 (3d Cir. 1955), Application of Kapatos, 208 F.Supp. 883 (S.D.N.Y. 1962), Smallwood v. Warden, 205 F.Supp. 325 (D.Md.1962). Note, supra note 8 at 139-142.
. 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963).
. 373 U.S. at 87, 83 S.Ct. at 1196 (emphasis added).
. The dissenting judge has indicated agreement with this principle.
The genesis, the basic- rationale of the duty of disclosure, placed only on *1212the prosecution in criminal cases, lies in the belief that giving criminal defendants counsel and the opportunity to call witnesses has not completely eliminated the reasons which led the common law, before these protections were provided, to require that the prosecutor present in court all evidence about an alleged crime, whether it helped his case or not.
The presumed — and ordinarily well founded- — superiority of the prosecution’s facilities for fact-gathering constitutes the basis for the duty to disc’ose exculpatory evidence and for the enforcement of it by setting aside co' victions secured in part because of its violation. Levin v. Katzenbach, 124 U.S.App.D.C. at 165, 363 F.2d at 294 (dissenting opinion).
See also Note supra note 8 at 142-145.
. Pyle v. State of Kansas, 317 U.S. at 216, 63 S.Ct. 177, 87 L.Ed. 214.
. United States ex rel. Thompson v. Dye, 221 F.2d at 765.
. Curran v. State of Delaware, 259 F.2d 707, 711 (3d Cir. 1958).
. United States ex rel. Butler v. Maroney, 319 F.2d 622, 627 (3d Cir. 1963).
. Ashley v. State of Texas, 319 F.2d 80, 85 (5th Cir. 1963).
. Griffin v. United States, 87 U.S.App.D.C. 172, 175, 183 F.2d 990, 993 (1950).
. Levin v. Katzenbach, 124 U.S.App.D.C. at 162, 363 F.2d at 291.
. Cf. Ashley v. State of Texas, supra note 18 ; United States ex rel. Butler v. Maroney, supra note 17 ; Note, supra note 8 at 145-147.
. 336 U.S. 704, 69 S.Ct. 814, 93 L.Ed. 993 (1949).
. 336 U.S. at 709, 69 S.Ct. at 816.
. The Government suggests that the trial court’s ruling must be “clearly erroneous” before we reverse. Although, for reasons stated below, we think the trial court’s evror is clear, we do not think the “clearly erroneous” standard is applicable. As we said in Jackson v. United States, 122 U.S.App.D.C. 324, 326, 353 F.2d 862, 864 (1965), we said “in reviewing facts * * * courts apply the ‘clearly erroneous’ standard * * Here, we are not reviewing facts. There is no dispute about what evidence the prosecutor failed to reveal. The only question is what legal conclusion follows from- this failure. We must review the trial court’s legal conclusion in the same way we review any other legal conclusion of a trial court.
. Olson’s testimony contradicted Landris-cina’s testimony that lie made the first payment to Levin on February 12. The Union’s cancelled check corroborated Olson’s testimony.
. Ashby’s testimony about the date of this transaction, also contradicted Landris-eina’s testimony.
. This fact came out during Ashby’s testimony before the Grand Jury.
. The dissent states that McCeney and Hooper did not remember cashing the $35,000 check until they consulted bank records. But the evidence on this point is contradictory; at the habeas hearing McCeney and Hooper recalled details of the transaction which would not be contained in records.
McCeney testified: Well, Mr. Olsen came into the bank and I contacted him there in the office and took him over to Mr. Hooper and he wanted large bills, I asked him how he wished the money and he said $1,000 bills and I took him to Mr. Hooper because he was handling the large denomination of bills at that time. * * * H.Tr. 131.
Hooper testified: Mr. Olson contacted one of our officers, Assistant Treasurer, Mr. McCeney, and asked him to cash this $35,000 check, which I had the thousand dollars bills [sic]. H.Tr. 52.
The witnesses seem to be describing a specific incident and not, as the dissent as-serfs, “established bank procedures concerning large bill transactions.”
In any event, the bank officials would be far more likely to remember exchanging thirty-five $1,000 bills than cashing a $35,000 check, since the former transaction is “very unusual” while the latter is not. Compare H.Tr. 63 with Government’s exhibit No. 3, pages 6, 7 quoted at 262 F.Supp. at 958.
. Although defense counsel also interviewed McCeney prior to trial, the interview was an informal one, and there is nothing in the record to suggest that the prosecutor knew about it. Moreover, even if the prosecutor did know about the interview, he had no reason to believe that, at this juncture, defense counsel was aware of the purported exchange of bills. (In fact, defense counsel did not know about the jjurported exchange when he interviewed McCeney.) Thus, the prosecutor had no reason to believe that the defense interview with McCeney touched on the crucial points covered in McCeney’s statement to the Government.
. McCeney’s and Hooper’s memory had been proved faulty in other matters. Levin v. Katzenbach, 262 F.Supp. at 958-959.
. Griffin v. United States, supra note 23 at 709.
. In part, the District Court’s ruling below was based on the fact that the exchange could have taken place without Hooper’s or McCeney’s knowledge. This ruling apparently ignores Ashby’s testimony before the Grand Jury that he dealt with McCeney when he exchanged the bills.