concurring.
I join Parts A-2, A-5 (subject to my comments on Part A-4), A-6, A-9, A-10, B, C, D, and E of the majority opinion, concur in the result relative to the balance, and offer the following comments organized according to the subject headings of the majority opinion.
A. Challenges to Evidentiary Rulings
1. Trial Court’s Exclusion of Kenneth Miller’s Testimony
I respectfully disagree with the majority’s conclusion that the trial court appropriately excluded a portion of prison supervisor Kenneth Miller’s testimony. See Majority Opinion, at 490-94, 28 A.3d at 873-75. Initially, the trial court sustained an objection to Mr. Miller’s testimony concerning Appellant’s ability to function in the general population as speculative. See N.T., at 779. Trial counsel responded by attempting to lay a further foundation. See id. The Commonwealth objected again on grounds of relevance, and the trial court explained:
Here’s the reason I’m sustaining [the objection]: The jury has to decide, they have to weigh aggravating and mitigating circumstances and they make their sentencing choice. Whatever the sentencing choice is, the Department of Corrections has to live with. So the adjustment of other inmates or what he thinks the adjustment might be I don’t think is *525relevant. And that’s the reason I’m sustaining the objection.
Id. at 780 (emphasis added).
As Appellant explains, the court was wrong in its relevance assessment. See Skipper v. South Carolina, 476 U.S. 1, 5, 106 S.Ct. 1669, 1671, 90 L.Ed.2d 1 (1986) (“[Evidence that the defendant would not pose a danger if spared (but incarcerated) must be considered potentially mitigating.”). Moreover, in ruling the opinion was irrelevant, the court foreclosed trial counsel’s efforts to establish a further foundation for admissibility. Thus, while the majority’s finding that Mr. Miller testified as a fact witness and not an expert may be correct, see Majority Opinion, at 493-94, 28 A.3d at 875, it is questionable whether the responsibility for this should fall to Appellant, where his counsel was not permitted to establish a foundation for the opinion. Moreover, the majority does not discuss the role of lay opinions. See Pa.R.E. 701.
In my view, the trial courts should extend a degree of latitude to capital defendants in presenting this type of testimony. Accord Valle v. State, 502 So.2d 1225, 1226 (Fla.1987) (awarding a new sentencing hearing on the basis that a trial court had improperly excluded testimony of a clinical psychologist and two corrections consultants proffered in support of the defendant’s claim that, if given a life sentence, he would be a model prisoner); People v. Lucero, 44 Cal.3d 1006, 245 Cal.Rptr. 185, 750 P.2d 1342, 1355 (1988) (following Valle). I find the Valle court’s approach to be a rational extension of the principle, from Skipper, that “a defendant must be allowed to present all relevant mitigating evidence to the jury in his efforts to secure [a life sentence].” Valle, 502 So.2d at 1226. Of course, the Commonwealth should also be free to present contrary evidence which is fairly responsive. See Commonwealth v. Hughes, 581 Pa. 274, 332-34 & n. 40, 865 A.2d 761, 796-97 & n. 40 (2004).1
*526While I therefore differ with the majority’s holding, I regard the trial court’s error as harmless, as the purport of Mr. Miller’s testimony (that he had known Appellant for ten years; Appellant had no misconducts; he was mature, polite and did his job well; he maintained the highest level of trust; and he got along well with other inmates, see N.T., at 767-769), suggested the opinion Appellant wished to adduce in any event. Moreover, Appellant was permitted to introduce a forensic psychiatrist’s opinion that he manifested a low potential for future aggression. See N.T., at 875. Notably, based on Appellant’s extensive mitigation case (including testimony from Appellant’s wife, his mother, school officials and teachers, numerous friends, neighbors, several clergypersons, a former attorney for Appellant, prison supervisors and guards, a corrections counselors, and a forensic psychiatrist), one or more jurors found that he had lived as a well-adjusted inmate since 1982, and that he had changed his life and adopted a Christian lifestyle. See N.T., at 1184-85. In the circumstances, and particularly given the strength of the Commonwealth’s case of aggravation, there does not seem to me to be a substantial likelihood of a different outcome had Mr. Miller been permitted — as I believe he should have — to offer an additional opinion concerning Appellant’s amenability to being introduced into the general inmate population.
3. Superior Court’s Ruling that Evidence of Positive Prison Adjustment is Rebuttable
The majority holds that the Commonwealth may present evidence of a defendant’s prior bad acts to rebut claims of rehabilitation, reform, and an associated lack of future dangerousness. See Majority Opinion, at 498-99, 28 A.3d at 878-79. One substantial obstacle to a reasoned application of such holding is that it is in conceptual tension with this Court’s position, for many years, that evidence of prior bad acts is not indicative of future dangerousness. See Commonwealth v. Chmiel, 585 Pa. 547, 611, 889 A.2d 501, 539 (2005) (“This Court has recognized consistently that evidence regarding a defendant’s past violent convictions or conduct does not implicate the issue of his or her future dangerousness.”). This analysis *527was developed in the context of the requirement for a life-means-life instruction under Simmons v. South Carolina, 512 U.S. 154, 114 S.Ct. 2187, 129 L.Ed.2d 133 (1994) (plurality), and there is some uncertainty in its application to matters tried after the United States Supreme Court’s decision in Kelly v. South Carolina, 534 U.S. 246, 253, 122 S.Ct. 726, 731, 151 L.Ed.2d 670 (2002) (explaining, in the context of Simmons, that “[a] jury hearing evidence of defendant’s demonstrated propensity for violence reasonably will conclude that he presents a risk of violent behavior[.]”). See, e.g., Commonwealth v. Spotz, 610 Pa. 17, 42-43, 18 A.3d 244, 302-03 (2011) (taking a narrow approach to Kelly’s application).
However Kelly is to be interpreted going forward, the underlying difficulty remains that the Court must enforce a narrowing approach to the death penalty statute to conform with the federal constitutional mandates of reasonable justification for the imposition of a more severe sentence on the defendant as compared to others convicted of murder, see Zant v. Stephens, 462 U.S. 862, 877, 103 S.Ct. 2733, 2742, 77 L.Ed.2d 235 (1983), and the opportunity for the capital defendant to adduce all relevant mitigating evidence, see Skipper, 476 U.S. at 4, 106 S.Ct. at 1671. In a number of respects, however, including the above, the appearance is that this Court is not enforcing such a narrowing construction. Cf. Commonwealth v. Houser, 610 Pa. 264, 279-82, 18 A.3d 1128, 1138-39 (2011) (Saylor, J., concurring and dissenting) (commenting on a judicial narrowing of a statutory mitigating circumstance in tension with the express statutory prescription).
I would permit a defendant to offer mitigation evidence of rehabilitation, reform, and prospects for a non-violent future as a prisoner without pain of lifting the general bar against such pre-incarceration other-bad-acts evidence as would be otherwise inadmissible.2 I offer my reasoning in this regard, also, as my response to Part A-7 of the Majority Opinion.
*5284. Evidence of Appellant’s Guilty Plea to the Nichols Homicide
As the majority indicates, the federal district court directed that Appellant be discharged from custody, unless the common pleas court held a resentencing hearing “at which evidence of his Indiana County guilty plea [in the matter of the killing of William Nichols] is excluded.” Majority Opinion, at 499-500, 28 A.3d at 879 (citation omitted). As the majority further explains, “the federal court order does not, on its face, link the preclusion of evidence of Appellant’s guilty plea to the Nichols homicide to an attempt by the Commonwealth to establish aggravating factors[.]” Majority Opinion, at 501-02, 28 A.3d at 880.
Thus, it is very troublesome to me that, in a 30-year-old capital litigation on resentencing per a federal court order, the Commonwealth would attempt (successfully) to do what the federal order said it could not, thus placing any ensuing death verdict at substantial risk on further federal review. The Commonwealth’s case for death encompassed compelling aggravation without the need to bring the compliance with the federal mandate into question.
The Commonwealth’s desire to impose capital punishment on Appellant for the heinous killing spree in which he participated (and, indeed, appears from the record to have led) is quite understandable. It also must be appreciated, however, that there are substantial downsides to a no-stones-unturned approach to death-penalty prosecution, for example, in terms of risk, delay, and uncertainty. It is my considered perspective that the Commonwealth should take a more conservative approach in these cases to minimize such factors in the multiple layers of close scrutiny ensuing upon issuance of a death verdict. With respect to the present case, I reiterate that a very strong case for death was put forth without recourse to the guilty plea and/or conviction pertaining to the killing of Mr. Nichols.
My vote to join in the result relative to this claim derives from the fact that there is at least some degree of ambiguity as to the intent of the federal order, given the federal magis*529trate’s footnoted pronouncement relied upon by the majority, see Majority Opinion, at 501-02, 28 A.3d at 880,3 and the analysis of the federal mandate is peculiarly a federal concern, particularly since the matter previously was exhausted in the Pennsylvania state court system.
8. Failure to Exclude Evidence of the Convenience Store Robbery
Finally, I question the bright-line rule the majority derives from Commonwealth v. Jones, 542 Pa. 464, 668 A.2d 491 (1995), which appears to suggest that the Court will not consider the admissibility and/or prejudicial character of Commonwealth evidence offered in connection with an aggravating circumstance, so long as the aggravator is not found by the jury. See Majority Opinion, at 511-13, 28 A.3d at 880-81. I am unable to reconcile such a categorical approach with the federal constitutional standard for harmless error pertaining on direct review, which appears to me to be circumstance specific. See Commonwealth v. Story, 476 Pa. 391, 409, 383 A.2d 155, 164 (1978). In this regard, I believe it to be the Commonwealth’s burden to establish, beyond a reasonable doubt, that the error did not contribute to the overall verdict (not just to the finding, or not, of an aggravator). See, e.g.,
*530Commonwealth v. Howard, 538 Pa. 86, 99-100, 645 A.2d 1300, 1307 (1994). Given the possibility that a prejudicial taint may impact sentencing proceedings more broadly than on the specific point for which the evidence is offered, a more searching review is required upon the discernment of a preserved trial-court error. I therefore join the majority on this point only upon my conclusion that the victim-impact evidence relative to the robbery was very modest in the context of the overall presentations of aggravation and mitigation, and therefore, the possibility of an effect on the outcome is insubstantial.
. In this regard, I would note only that the Commonwealth is restricted to the character trait placed at issue by the defense. See id.
. Significantly, the Commonwealth was appropriately permitted to introduce rebuttal evidence concerning Appellant’s misconduct in prison. See, e.g., N.T., at 1027-28.
. The counter-position, of course, is that the arrangement to defer sentencing encompassed a preclusion of any use of the conviction pertaining to the Nichols homicide, since, under the agreement, the Indiana County conviction simply would not come into being until after the Westmoreland County trial. There is as much (and more) language in the federal magistrate’s report and recommendation supporting such a broader perspective regarding the preclusion as there is to bolster the majority’s narrowing construction. See, e.g., Report and Recommendation, Travaglia v. Morgan, Civ. No. 90-1469, slip op. at 14 (W.D.Pa. Oct. 7, 1996) (indicating that various of Appellant's attorneys testified to their belief in "assurances ... that the plea could not be used against [Appellant] in Westmoreland County”); id. at 15 (referencing testimony to the effect that sentencing was repeatedly postponed in Indiana County at the request of the assistant district attorney "to insure that the plea could not be introduced during the Westmoreland County trial”); id. (crediting such testimony as establishing that “all the parties involved in [Appellant's] case ... believed that the plea petitioner entered in Indiana could not be used in the Westmoreland County trial”). As the majority otherwise recognizes, the actual federal order is consistent with the broader approach.