I concur in the majority opinion. Specifically, I agree that to place the burden in a retrospective competency hearing on defendant to prove his incompetency by a preponderance of the evidence is constitutional. I also agree that not before us are the legal issues whether “(1) [whether] the federal constitutional error in failing to evaluate defendant’s mental competence at the time of trial might be ‘cured’ by means of a retrospective competency hearing” (maj. opn., ante, at pp. 516-517), and (2) whether the prosecution need prove the feasibility of a retrospective hearing beyond a reasonable doubt, these questions having been conclusively settled for purposes of this case in the lower court.
Although I agree the law-of-the-case doctrine precludes our addressing the above issues, our decision should not obscure the fact the issues we avoid are significant and unresolved. When the United States Supreme Court first established an accused’s due process right to a hearing upon presentation of a reasonable doubt as to his or her competency to stand trial, that court simply reversed the judgment against the accused, specifically rejecting the claim “that it would be sufficient for the state court to hold a limited hearing as to [the defendant’s] mental competence at the time he was tried . . . .” (Pate v. Robinson (1966) 383 U.S. 375, 387 [15 L.Ed.2d 815, 86 S.Ct. 836]; see also Drope v. Missouri (1975) 420 U.S. 162, 183 [43 L.Ed.2d 103, 95 S.Ct. 896].) This court has done the same. (People v. Marks (1988) 45 Cal.3d 1335, 1340 [248 Cal.Rptr. 874, 756 P.2d 260] [reversing the judgment, noting, “[t]hat the hearing was not held is dispositive”]; People v. Hale (1988) 44 Cal.3d 531, 541 [244 Cal.Rptr. 114, 749 P.2d 769] [failure to hold hearing “rendered the subsequent trial proceedings void because the court had been divested of *522jurisdiction to proceed”]; People v. Pennington (1967) 66 Cal.2d 508, 521 [58 Cal.Rptr. 374, 426 P.2d 942] [specifically rejecting the suggestion that “the error be cured by a retrospective determination of defendant’s mental competence during his trial”]; see also People v. Welch (1999) 20 Cal.4th 701, 738 [85 Cal.Rptr.2d 203, 976 P.2d 754] [where substantial evidence of the defendant’s incompetency is presented but a hearing is not held, “the judgment must be reversed”].) In recent years, however, some lower federal and state courts have taken the position that such error can be cured by a remand to hold a retrospective, or nunc pro tunc, competency hearing.1
Reason exists to believe the United States Supreme Court would not approve the procedure. For example, when, in Drope v. Missouri, supra, 420 U.S. 162, the high court faced the prospect of remanding for a hearing to determine the state of the defendant’s competency six years earlier, it opined: “Given the inherent difficulties of such a nunc pro tunc determination under the most favorable circumstances, [citations], we cannot conclude that such a procedure would be adequate here.” (Id. at p. 183.) Similarly, in Dusky v. United States (1960) 362 U.S. 402, 403 [4 L.Ed.2d 824, 80 S.Ct. 788] (per curiam), the court noted: “In view of the doubts and ambiguities regarding the legal significance of the psychiatric testimony in this case and the resulting difficulties of retrospectively determining the petitioner’s competency as of more than a year ago, we reverse the judgment . . . .” (Italics added.)
The Court of Appeal’s decision below in People v. Ary, supra, 118 Cal.App.4th 1016—the decision we find controlling here—was the first California case to approve the remand procedure. We recognized that holding (but did not necessarily endorse it) in People v. Young (2005) 34 Cal.4th 1149, 1216-1217 and footnote 16 [24 Cal.Rptr.3d 112, 105 P.3d 487], The issue therefore remains an open one in this court.
Whether the People bear the burden to prove on remand that a retrospective hearing is still feasible and, if so, whether their burden of proof is by a preponderance or beyond a reasonable doubt, are similarly unsettled. As the *523majority explains, these issues also are not before us in this case and we thus express no opinion on, for example, whether the Court of Appeal correctly decided to impose the lesser burden of proof on the People.
With those caveats, I concur.
See, e.g., Odle v. Woodford (9th Cir. 2001) 238 F.3d 1084, 1089 (“The state court can nonetheless cure its failure to hold a competency hearing at the time of trial by conducting one retroactively”); Moran v. Godinez (9th Cir. 1994) 57 F.3d 690, 696 (“retrospective competency hearings are disfavored” but “permissible whenever a court can conduct a meaningful hearing to evaluate retrospectively the competency of the defendant”); People v. Robinson (2007) 151 Cal.App.4th 606, 617-618 [60 Cal.Rptr.3d 102] (retrospective competency hearings are possible depending on the circumstances); People v. Kaplan (2007) 149 Cal.App.4th 372, 388-389 [57 Cal.Rptr.3d 143] (same); see also People v. Ary (2004) 118 Cal.App.4th 1016, 1029 [13 Cal.Rptr.3d 482] (retrospective competency hearings for Pate error should be done in “rare circumstances”).