(concurring):
In concur with the majority’s conclusion that the Pennsylvania practice challenged here operated to deprive Matthews of due process of law.
Ordinarily, I exercise great caution and considerable hesitancy before concluding that a state practice or statute is unconstitutional. However, the Supreme Court of Pennsylvania has just recently ordained that, upon request, every murder defendant in the Commonwealth is entitled to a voluntary manslaughter instruction, whether in felony murder or general murder trials.1 Although that ruling is, by its terms, made prospective only, it indicates that Pennsylvania has abandoned whatever stake it may have had in the rule of criminal procedure that a defendant is not entitled to such an instruction absent evidence of passion or provocation. Thus, the effect worked upon Pennsylvania’s criminal justice system by the Court’s ruling today is not seriously at odds with Pennsylvania’s own perception of its interests. In these circumstances, we generate no undue friction, or at least a minimum of exacerbation, between a state and the federal system by holding the former Pennsylvania practice unconstitutional.
I agree with the majority that the lack of any articulable criteria for the giving or withholding of a manslaughter instruction where there was no evidence of passion or provocation made for stand-ardless, “ad hoc and episodic” justice,2 and as such constituted a violation of due process.3 It would seem unwise, however, simply to accept a statement from a dissenting opinion in Commonwealth v. Matthews 4 as a conclusive exposition of prior Pennsylvania practice. Rather, in my judgment, we are bound to survey all the Pennsylvania Supreme Court opinions on the subject, and to determine from them what appears to have been the Pennsylvania rule or practice. Having undertaken such an examination, I am satisfied that, in the past, trial judges in Pennsylvania had discretion to give or withhold a manslaughter instruction where no evidence of passion or provocation had been adduced. In no case that has come to my attention did the giving or withholding of the instruction lead to a reversal, or even to critical comment by the reviewing tribunal.
The dissent has pointed out that Matthews was found guilty of felony murder, as distinguished from a general murder charge, and that, whatever the situation regarding general murder, a judge under Pennsylvania law is “justified in refusing to charge upon the law of manslaughter” in a felony murder prosecution.5 This view is grounded in the recognition that it is not logical to speak of “passion or provocation” when felony *350murder is involved.® Although there are cases which hold that a defendant is not entitled to a manslaughter charge when there is no evidence of passion or provocation in the record, no case has been called to my attention that has mandated the withholding of a manslaughter charge in a felony murder case, and, indeed, there appears to be some indication that manslaughter charges have been given, from time to time, when there has been no evidence of passion or provocation. It is apparent, therefore, that state trial judges were without standards, supplied either by the legislature or by the appellate courts, to guide them in the giving or withholding of voluntary manslaughter instructions, not only in cases of general murder but in felony murder cases as well.
Moreover, there is no indication that Pennsylvania trial judges, themselves, felt constrained by any standards in the giving or withholding of such an instruction, whether in general murder or felony murder cases. A review of state decisions would appear to disclose that while some juries were given the instruction, others were not,6 7 and no explanation for giving or withholding such an instruction was required. Thus, besides fostering the potential for prejudice and arbitrariness, the prior Pennsylvania practice appears actually to have resulted in unexplicated discrimination among murder defendants.8
Nor can this discrimination be deemed harmless beyond a reasonable doubt, since there is no way of ascertaining how the jury in this case would have responded had it been given a manslaughter instruction.9
. Commonwealth v. Jones, Pa., 319 A.2d 142 (1974).
. Rochin v. California, 342 U.S. 165, 172, 72 S.Ct. 205, 96 L.Ed. 183 (1952).
. It would appear that Giaccio v. Pennsylvania, 382 U.S. 399, 86 S.Ct. 518, 15 L.Ed.2d 447 (1966), provides an apt description of the due process guideline to be applied in this case.
. Majority Opinion at 341.
. In this connection the dissent refers to Commonwealth v. Meleski, 278 Pa. 383, 123 A. 310 (1924), and Commonwealth v. Davis, 449 Pa. 468, 297 A.2d 817 (1972), cert. denied 414 U.S. 836, 94 S.Ct. 183, 38 L.Ed.2d 72 (1973). However, in Davis, only a plurality of three justices stated that in a felony murder prosecution it is “perfectly proper for a trial judge to eliminate completely the jury’s consideration of a voluntary manslaughter verdict.” Id. at 821.
. While logic perhaps supports the elimination of “passion or provocation” in the felony murder situation, this view might nonetheless reflect an overly narrow concept of the jury’s role. The jury historically functioned not only as fact finder but as a tempering element in criminal prosecutions. As Mr. Justice Nix observed in his Opinion in Support of Affirmance in Commonwealth v. Jones, Pa., 319 A.2d 142, 146 (1974), the capacity of the jury to find voluntary manslaughter even without evidentiary support derives particularly from its “historically recognized mercy dispensing power.” Id. at 150. The absence of a logical basis for a voluntary manslaughter charge is thus not conclusive of the issue.
. See, e. g., Commonwealth v. Cannon, 453 Pa. 389, 309 A.2d 384 (1973); Commonwealth v. Butcher, supra; Commonwealth v. Dennis, 433 Pa. 525, 252 A.2d 671 (1969).
. Were there an indication that trial judges in Pennsylvania never gave the voluntary manslaughter charge in the absence of- evidence of passion or provocation, there would be serious reservations, at least in my mind, whether the absence of a clearly articulable standard constituted a due process violation. Too, since Matthews was convicted for felony murder, there would be no due process violation in this case if there were standards governing the giving of a manslaughter instruction in felony murder cases, even if there were no standard for general murder cases. Thus, until the Jones case, in 1974, there were no such standards in either type of case.
. Harrison v. United States, 392 U.S. 219, 88 S.Ct. 2008, 20 L.Ed.2d 1047 (1968); Chapman v. California, 386 U.S. 18, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967); United States ex rel. Macon v. Yeager, 476 F.2d 613 (3d Cir. 1973).