concurring in part and dissenting in part.
I concur in Divisions 1, 2, 3 (a) and 4 of the majority opinion and in the judgment of reversal. However, I believe that a claim for habeas relief based upon an allegation of mental retardation is subject to procedural default and that the habeas court erred, therefore, in considering the issue of Hill’s alleged mental retardation under any standard. Accordingly, I respectfully disagree with Division 3 (b) of the majority opinion and dissent to the remand for the habeas court’s further consideration of Hill’s claim of mental retardation.
Although Hill did not raise his alleged mental retardation as a bar to the death penalty at the guilt-innocence phase of the trial, the majority nevertheless concludes that the habeas court is authorized to address that belated claim under the “miscarriage of justice” exception to the principle of procedural default. “In precisely the same vein” as federal law, OCGA § 9-14-48 (d) incorporates this limited “miscarriage of justice” exception into our state habeas corpus statute. Valenzuela v. Newsome, 253 Ga. 793, 796 (4) (325 SE2d 370) (1985). Even in death-penalty cases, the United States Supreme Court has “emphasized the narrow scope of the . . . exception.” Sawyer v. Whitley, 505 U. S. 333, 340 (112 SC 2514, 120 LE2d 269) (1992). Consistent with “the core purpose of the writ — which is to free the innocent wrongfully deprived of their liberty,” we have restricted the “miscarriage of justice” exception to “rare” occasions. Valenzuela v. Newsome, supra at 796 (4). This restriction is essential to preserve judicial resources and the finality of judgments. Sawyer v. Whitley, supra at 338; Valenzuela v. Newsome, supra at 796 (4).
“ ‘[T]he term [“miscarriage of justice”] is by no means to be deemed synonymous with procedural irregularity, or even with reversible error. To the contrary, it demands a much greater substance, approaching perhaps the imprisonment of one who, not only is not guilty of the specific offense for which he is convicted, but, further, is not even culpable in the circumstances under inquiry.”
(Emphasis in original.) Gavin v. Vasquez, 261 Ga. 568, 569 (407 SE2d 756) (1991).
The majority’s reliance upon Fleming v. Zant, 259 Ga. 687, 690 (3) (386 SE2d 339) (1989) as support for its application of the “miscarriage of justice” exception is misplaced. Contrary to the implication of the majority, the constitutional dimension of an issue raised in a habeas proceeding does not in and of itself demonstrate a “miscarriage of justice.” See Black v. Hardin, 255 Ga. 239, 240 (5) (336 SE2d 754) (1985). More importantly, however, this Court in Fleming v. Zant, supra at 690 (3), expressly disavowed any holding “that the *306Georgia Constitution prohibits execution of retarded persons per se.” Indeed, the holding in Fleming was based in significant part upon the relevant statutory provision of OCGA § 17-7-131 (j), as a reflection of the will of the people through their elected representatives. Fleming’s procedure was expressly held inapplicable in those cases where the statute was applicable. Fleming, supra at 691 (4), fn. 4. This case is controlled by OCGA § 17-7-131 (j), not by Fleming. Thus, in this case, the statute is the standard which reflects the will of the people of Georgia and their consensus on what constitutes unconstitutional cruel and unusual punishment. See Burgess v. State, 264 Ga. 777, 790 (36) (450 SE2d 680) (1994) (holding that “[t]here is no constitutional impediment to th[e] statutory requirement that the defendant meet a beyond a reasonable doubt standard as to the issue of mental retardation.” (Emphasis supplied.)).
The public policy evidenced by the death-penalty preclusion of OCGA § 17-7-131 (j) is that it constitutes cruel and unusual punishment to execute only those defendants who have met the burden of proving their mental retardation beyond a reasonable doubt at the guilt-innocence phase in accordance with OCGA § 17-7-131 (c) (3).
(Emphasis supplied.) Burgess v. State, supra at 790 (36). There is no contention that Hill could not have attempted to raise his mental retardation as a bar to the death penalty at the guilt-innocence phase of his trial in accordance with the statute. However, he made no attempt to do so. Under the testimony of his own expert at the sentencing phase, Hill was not mentally retarded, but was merely on the “borderline.” If Hill was not mentally retarded, then, as a matter of Georgia statutory and constitutional law, the death penalty would not constitute cruel and unusual punishment. In Burgess, this Court correctly distinguished OCGA § 17-10-60 et seq., which provides a post-conviction procedure for obtaining a stay of execution based upon mental incompetency.
Moreover, the “miscarriage of justice” exception in the setting of capital punishment is, as previously noted, “a very narrow exception, and ... to make it workable it must be subject to determination by relatively objective standards.” Sawyer v. Whitley, supra at 341. Mental retardation is not the kind of objective, easily determined condition of eligibility for the death penalty contemplated by Sawyer v. Whitley, supra at 346-347. To the contrary, the determination of mental retardation as defined by OCGA § 17-7-131 (a) (3) is complex. Furthermore, unless mental retardation is raised by the defendant and proved beyond a reasonable doubt at the guilt phase, evidence thereof is merely “additional mitigating evidence,” the absence of *307which at the sentencing phase would not constitute a “miscarriage of justice.” Sawyer v. Whitley, supra at 347. See also Burgess v. State, supra at 791 (36).
Even if the majority were generally correct in applying the “miscarriage of justice” exception to claims of mental retardation, there certainly is no miscarriage of justice under the circumstances of this case. As previously noted, Hill’s trial counsel obtained evidence from a licensed clinical psychologist that Hill is not mentally retarded, but is on the “borderline.” Hill’s trial counsel could reasonably have concluded that if this evidence had been presented at the guilt-innocence phase it probably would not have resulted in a verdict of “guilty but mentally retarded” so as to preclude the imposition of the death penalty as a matter of law pursuant to OCGA § 17-7-131 (j). In light of the strong evidence presented at Hill’s sentencing trial that he is not mentally retarded, the concept of “miscarriage of justice” should not be used as the basis for authorizing a relitigation of the issue and second-guessing of trial counsel’s strategic choice.
That the effect of the majority opinion is a relitigation of the issue of mental retardation is apparent from the first footnote. That footnote indicates that Hill’s petition is based in part on evidence from the expert psychologist which is impeaching of his own trial testimony. Such evidence would not even furnish a basis for granting a motion for new trial. See,, e.g., Weems v. State, 268 Ga. 142, 143 (1) (485 SE2d 767) (1997); Ruger v. State, 263 Ga. 548, 551 (2) (c) (436 SE2d 485) (1993). Surely this evidence should not provide a basis for subsequent habeas relief when OCGA § 9-14-48 (d) imposes the stricter requirements of cause and prejudice or miscarriage of justice. In either instance, a contrary rule would encourage a lack of diligence by litigants, counsel, and expert witnesses on the first trial, would cause delay in the administration of justice, and would result in additional time, labor, and expense of further litigation. See Turner v. State, 44 Ga. App. 346, 348-349 (3) (161 SE 626) (1931). Therefore, in my opinion, Hill should not be permitted to support his petition with evidence which is merely impeaching or otherwise to relitigate the issue of mental retardation.
Under today’s holding, every defendant facing the possibility of the death penalty may, with this Court’s blessing, choose not to raise the issue of mental retardation as a bar to the death penalty at the guilt-innocence phase, in order to delay the determination thereof until a habeas petition is filed. Every such defendant who was tried after the effective date of OCGA § 17-7-131 (j) and sentenced to death is now automatically entitled to litigate or even to relitigate the issue of mental retardation at a habeas hearing. In my opinion, this is not one of those “rare” occasions where such a result should be authorized. Therefore, I dissent to the remand for any further considera*308tion of the mental retardation claim.
Decided February 23, 1998 Reconsideration denied April 2,1998. Thurbert E. Baker, Attorney General, Susan V. Boleyn, Senior Assistant Attorney General, for appellant. Stephen C. Bayliss, for appellee. Daniel J. Porter, District Attorney, Gwinnett Circuit, Peter J. Skandalakis, District Attorney, Coweta Circuit, Kermit N. McManus, District Attorney, Conasauga Circuit, Alvin G. Hollingshed, amici curiae.I am authorized to state that Justice Thompson joins in this dissent.