dissenting:
¶ 1 Were this a case of the Commonwealth’s non-disclosure of exculpatory evidence that Appellant discovered after conviction and sentencing, then I would agree with the Majority that the relative character of the evidence we are considering here is not constitutionally material and would not impeach the verdict so as to necessitate the grant of a new trial. However, I conclude that the facts of this case are substantially different, and that the trial court’s ruling deprived Appellant of a fair trial.
¶ 2 In the instant case, exculpatory evidence in the form of a letter written by Ricardo Jones to the police inculpating two individuals other than Appellant was not disclosed pre-trial, but was disclosed during trial. In particular, the trial court overruled defense counsel’s objection to the admission of this evidence, which objection was lodged on the bases that the letter was first disclosed to the defense after Jones had already testified on direct examination and that the admission of the letter would effectively torpedo Appellant’s theory of defense by impeaching Jones’ testimony that Appellant was not present when the victim was assaulted. Consequently, faced with such a violation of Appellant’s right to due process, I am compelled to respectfully dissent.
¶ 3 “In Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963), the United States Supreme Court held ‘that suppression by the prosecutor of evidence favorable to an accused upon request vio*410lates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution.’ ” Commonwealth v. Moose, 529 Pa. 218, 602 A.2d 1265, 1272 (1992). Pursuant to Pa.R.Crim.P. 573, the Commonwealth has the following duty to disclose evidence to a defendant:
Rule 573. Pretrial Discovery and Inspection.
(B) Disclosure by the Commonwealth
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(1) Mandatory:
In all court cases, on request by the defendant, and subject to any protective order which the Commonwealth might obtain under this rule, the Commonwealth shall disclose to the defendant’s attorney all of the following requested items or information, provided they are material to the instant case.
(a) Any evidence favorable to the accused that is material either to guilt or to punishment, and is within the possession or control of the attorney for the Commonwealth;
Pa.R.Crim.P. 573(B). “The purpose of the discovery rules is to permit the parties in a criminal matter to be prepared for trial. Trial by ambush is contrary to the spirit and letter of those rules and cannot be condoned.” Moose, 602 A.2d at 1274.
¶ 4 Under Rule 573, the Commonwealth has a duty to disclose all material evidence favorable to the defendant. Pa.R.Crim.P. 573. This includes any such evidence of which the Commonwealth becomes aware and has reason to believe would assist the accused in establishing his innocence or reducing punishment. See Commonwealth v. Montgomery, 533 Pa. 491, 626 A.2d 109 (1993). This affirmative duty is ongoing throughout the trial process and favors immediate disclosure by the Commonwealth upon its receipt of such evidence. Id. Furthermore, when assessing the materiality of evidence to the defendant’s case, both the defendant’s ability to adequately prepare and present a defense must be considered. Any adverse effect such nondisclosure would cause to a defendant’s trial strategy must be weighed in determining whether the evidence should be deemed material: See United States v. Bagley, 473 U.S. 667, 105 S.Ct. 3375, 87 L.Ed.2d 481 (1985).
¶ 5 In the instant case, the evidence in question, Jones’ written statement to the police, is material for a number of reasons. First, it creates a reasonable doubt which did not otherwise exist, as it offers a scenario of the assault which implicates two men other than Appellant. This is clearly exculpatory since it is evidence that Appellant did not commit the crime of which he was accused. Secondly, there is little doubt that Appellant would have altered his trial strategy had he been privy to Jones’ letter prior to trial. Had Appellant known about this letter, he could have used it in his defense to raise a reasonable doubt as to who was actually responsible for the assault of Cambra. In the alternative, Appellant could have used this information to confront Jones about his prior inconsistent statement before calling him to the stand. Further, it is quite likely that given Jones’ questionable credibility Appellant would have chosen not to call him as a witness at all. By waiting until after Jones took the stand to reveal the letter as impeachment evidence, the Commonwealth engaged in an unacceptable ambush of Appellant’s sole witness given its ongoing duty under Rule 573 to disclose all favorable evidence to Appellant.
¶ 6 In Commonwealth v. Ulen, 539 Pa. 51, 650 A.2d 416 (1994), our Supreme Court addressed the issue of what would constitute the proper remedy for the Commonwealth’s failure to disclose in a substantially similar factual scenario. In *411Ulen, the defendant and an individual named Aleta Bell were arrested on drug charges in a public restroom. The only-physical evidence against the defendant was a syringe containing cocaine and a packet containing cocaine closeby. There were no fingerprints on either.
¶ 7 At trial, the defendant called James Henry to testify on his behalf. Henry testified that he had seen Bell earlier that night with a syringe and a balloon. This testimony was offered in an effort to prove that the cocaine and syringe found next to the defendant and Bell did not belong to the defendant, but rather to Bell. Henry also testified that he had not discussed the case with anyone other than his mother, the defendant’s counsel, and Bell.
¶ 8 In rebuttal, the Commonwealth called Charleene Bullock who had known Bell from prison. Bullock testified that Henry had contacted her and arranged a meeting between herself, Henry and the defendant. At this meeting, the defendant agreed to “take care of’ Bullock if she testified that during her time with Bell in prison, Bell confessed that she was the one who possessed the drugs. Of course, this rebuttal testimony impeached Henry’s testimony that he had not discussed the case with anyone other than his mother, the defendant’s counsel, and Bell. The Commonwealth also offered to play a tape recording of the conversation between Bullock and Henry, and defense counsel objected. The tape was not given to defense counsel before trial, and defense counsel objected that this was a violation of the Commonwealth’s discovery obligation. The trial court overruled the objection.
¶ 9 In concluding that the Commonwealth violated Rule 573 (then numbered Rule 305), and that the defendant was entitled to a new a trial, the Court stated:
The purpose of RULE 305 is to prevent trial by ambush which, of course, leads to a denial of due process. Protestations by the Commonwealth (brief, p. 18) that the defense was given adequate remedy by being provided during trial with a transcript and discovery of the tapes ring hollow in light of the fact that Henry had already testified. That, of course, is the chief problem: whether defense counsel would have even called Henry had he known of the existence of these tapes or simply have relied for its chances on prosecution testimony alone.
Ulen, 650 A.2d at 419.
¶ 10 I conclude that we are faced with a similar “chief problem” in this case. Thus, the fact that the letter was not disclosed until after Jones testified, and that the trial court then allowed the Commonwealth to use the letter to impeach Jones is to me a pivotal point in the disposition of this case. The Majority, on the other hand, never engages this issue. Rather, the Majority anchors its analysis with such conclusions as: “The proffered impeachment evidence on which the defendant relies is not sufficiently favorable, and its suppression was not sufficiently prejudicial, to satisfy the constitutional threshold of materiality; ” and “Although we do not condone the apparent lack of diligence that prompted the Commonwealth’s non-disclosure, we do not find it a sufficient reason on which to grant a new trial.” Majority Opinion at 407-08, 409 (emphasis added). Again, were this a case of simple nondisclosure then I would agree with the Majority. Instead this is a ease of a criminal defendant being deprived of a fair trial due to the trial court permitting the Commonwealth to introduce evidence that should have been precluded due to a violation of Rule 573. I cannot sanction such a *412ruling, and accordingly, I record my dissent.