I concur in the judgment.
I agree with the majority’s disposition upholding the Court of Appeal’s refusal to grant defendant relief by writ of mandate: his motion attacking a prior-murder-conviction special-circumstance allegation under the 1978 death penalty law as resting on a conviction invalid on Boykin-Tahl grounds (Boykin v. Alabama (1969) 395 U.S. 238 [23 L.Ed.2d 274, 89 S.Ct. 1709]; In re Tahl (1969) 1 Cal.3d 122 [81 Cal.Rptr. 577, 460 P.2d 449]) was properly denied by the trial court.
I do not agree, however, with the majority’s reasoning. My analysis is as follows.
First, both the People and the defendant have a right to a determination by a jury as to the truth of any special circumstance allegations. (Pen. Code, § 190.4, subd. (a).) On this point there is no dispute.
Second, the People bear the burden of proving the truth of any special circumstance allegations beyond a reasonable doubt. (See Pen. Code, § 190.4, subd. (a).) On this point too there is no dispute.
Third, the prior-murder-conviction special circumstance is defined in relevant part as follows: “The defendant was previously convicted of murder in the first degree or second degree.” (Pen. Code, § 190.2, subd. (a)(2).)
The construction of this special circumstance is critical. It may be interpreted to require either a prior conviction simpliciter or a prior conviction that is valid.
*1308Inasmuch as the crucial function of special circumstances under the 1978 death penalty law is to delimit eligibility for capital punishment—i.e., to furnish the “ ‘meaningful basis [required by the Eighth Amendment] for distinguishing the few cases in which [the death penalty] is imposed from the many cases in which it is not’ ” (People v. Anderson (1987) 43 Cal.3d 1104, 1147 [240 Cal.Rptr. 585, 742 P.2d 1306], quoting Furman v. Georgia (1972) 408 U.S. 238, 313 [33 L.Ed.2d 346, 392 92 S.Ct. 2726] (conc. opn. of White, J.))—the latter interpretation should be adopted and the former rejected: the prior-murder-conviction special circumstance requires a prior conviction that is valid.
The majority arrive at the opposite conclusion. Their reasoning, however, is fatally flawed. They state that under Penal Code section 190.1, “The jury sitting as trier of fact must determine [only] ‘the truth of’ the prior conviction—i.e., the fact that defendant was previously convicted of first or second degree murder.” (Maj. opn., ante, at p. 1301.) Not so. Under that provision, the jury must determine the truth of the prior-murder-conviction allegation. Whether the underlying special circumstance includes only the fact of such conviction as an element or both fact and validity is the crucial question before the court. The majority do not resolve that question, but merely avoid it by ipse dixit.
From the foregoing it follows that to establish the truth of a prior-murder-conviction special circumstance, the People must prove both the fact and the validity of a prior murder conviction—and must do so beyond a reasonable doubt. The majority conclude that the burden of proving invalidity rests on the defendant and that the standard is preponderance of the evidence. That conclusion allows death eligibility to be predicated on a conviction that is as likely to be invalid as valid. Such a result is altogether untenable.
It also follows that both the People and the defendant have a right to a jury determination of the existence of the “fact” and “validity” elements. Therefore, the defendant may not effectively deprive the People of their right by means of a pretrial motion to strike the special circumstance allegation pursuant to People v. Coffey (1967) 67 Cal.2d 204 [60 Cal.Rptr. 457, 430 P.2d 15], and People v. Sumstine (1984) 36 Cal.3d 909 [206 Cal.Rptr. 707, 687 P.2d 904]. He may, of course, seek to set aside the allegation prior to trial by means of a motion pursuant to Penal Code section 995. Under that procedure, it is he who bears the burden of proof: to prevail, he must show that the allegation is not supported by “reasonable or probable cause” (see Pen. Code, § 995, subd. (a)).
In this case, defendant made what may be deemed a Penal Code section 995 motion to set aside the prior-murder-conviction special-circumstance *1309allegation. As noted, he claimed that the underlying conviction was invalid on Boykin-Tahl grounds. The trial court rejected the point—in my view, rightly. Its consequent denial of the motion was therefore proper: defendant simply failed to show that the allegation was not supported by “reasonable or probable cause.” It follows that the Court of Appeal’s refusal of relief by writ of mandate was correct.
For the foregoing reasons, although I do not join in the majority’s analysis, I nevertheless join in their disposition.