Justice, dissenting.
I dissent from the majority opinion because I am convinced that the refusal by a trial court to permit cross-examination of a Commonwealth witness as to bias is reversible error.
When the issue is whether the incriminating testimony may flow from a possible promise of leniency to the witness by the prosecution, any limitation on such cross-examination implicates the basic fairness of the right of confrontation and rises to the level of major prejudice to the defendant.
It is the burden of the Commonwealth to prove harmlessness. Commonwealth v. Haight, 514 Pa. 438, 525 A.2d 1199 (1987). In certain instances, moreover, harmless error will never lie, as we recently held in Commonwealth v. Lewis, 528 Pa. 440, 598 A.2d 975 (1991) (failure of a trial judge to instruct a jury that they cannot draw an adverse inference from a failure to testify cannot be harmless error). By contrast, as I have argued in my recent dissent in Commonwealth v. Janet Butler, 529 Pa. 7, 601 A.2d 268 (1991), I would permit a trial court to use its discretion to limit cross-examination where “there are other ways to establish the bias of the witness.” That, however, is not the situation in this case.
As the majority holds, Commonwealth v. Story, 476 Pa. 391, 383 A.2d 155 (1978), demands that it must be “clear beyond a reasonable doubt that the error could not have contributed to the verdict.” 476 Pa. at 417, 383 A.2d 155. If there is a possibility that the error contributed to the verdict, however, harmless error will not lie because the two findings are mutually exclusive. (See, Commonwealth v. Rodriguez, 533 Pa. 555, 626 A.2d 141 (1993), opinion authored by Justice Montemuro, construing Story and Commonwealth v. Foy, 531 Pa. 322, 612 A.2d 1349 (1992)). Whether cumulative or not, here a prosecution witness gave incriminating testimony in the face of the trial court’s refusal to permit his impeachment on the stand. As a consequence, the jury had no way of determining the credibility of the witness.
*91Even more compelling in this regard is the majority’s failure to read the critical portion of Commonwealth v. Evans, 511 Pa. 214, 512 A.2d 626 (1986):
... Whenever a prosecution witness may be biased in favor of the prosecution because of outstanding criminal charges or because of any non-final criminal disposition against him within the same jurisdiction, that possible bias, in fairness, must be made known to the jury. Even if the prosecutor has made no promises, either on the present case or on other pending criminal matters, the witness may hope for favorable treatment from the prosecutor if the witness presently testifies in a way that is helpful to the prosecution. And if that possibility exists, the jury should know about it. The jury may choose to believe the witness even after it learns of actual promises made or possible promises of leniency which may be made in the future, but the defendant, under the right guaranteed in the Pennsylvania Constitution to confront witnesses against him, must have the opportunity at least to raise a doubt in the mind of the jury as to whether the prosecution witness is biased. It is not for the court to determine whether the cross-examination for bias would affect the jury’s determination of the case.
Thus, we hold that the right guaranteed by Art. I Section 9 of the Pennsylvania Constitution to confront witnesses against a defendant in a criminal case entails that a criminal defendant must be permitted to challenge a witness’s self-interest by questioning him about possible or actual favored treatment by the prosecuting authority in the case at bar, or in any other non-final matter involving the same prosecuting authority.
Reversed and remanded for a new trial.
511 Pa. at 224-226 (citations omitted; emphasis added).
If the underscored words do not lay down a per se rule, then I don’t know what per se means. Evans mandates cross-examination and the trial court cannot restrict same. The majority is obfuscating Evans rather than reaffirming it.
*92Although the facts herein indicate that no charges were pending or promises of future leniency made to this witness, the fact remains that he had been given a substantial reduction in the charge against him in Pennsylvania. He was either extremely lucky or the Commonwealth heard his pleas when it was known to all that he would be a prosecution witness. I choose to believe the latter. While luck may not be a matter cognizable at law, a defendant has an absolute right to inquire into “possible” reasons for the reduction charges and penalties. The fact that the charges against the -witness were no longer pending is of no concern, as the majority agrees.
I conclude that we must reaffirm Evans. As in Lewis, a failure to allow cross-examination on leniency is one of those issues which mandates a finding of prejudicial error based on a constitutional right of confrontation.