Opinion
EAGLESON J.
We granted review in this case to settle the question of whether the constitutional validity of a prior murder conviction underlying a [1296]*1296prior-murder special circumstance may be collaterally attacked via a pretrial motion to strike the special circumstance, and to further determine the applicable standard of proof by which the invalidity of the prior conviction must be established in order to support the striking of the special circumstance.
We hold that in a capital prosecution, the defendant may challenge the constitutional validity of a prior murder conviction alleged as a prior-murder special circumstance by a pretrial motion to strike the special circumstance allegation, and that the defendant is entitled to an evidentiary hearing on such a motion, conducted pursuant to the procedures set forth in 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], As we shall further explain, in such a proceeding the defendant seeking to collaterally attack the validity of his prior murder conviction has the burden of proving its constitutional invalidity by a preponderance of the evidence. (Evid. Code, § 115.) As defendant’s motion to strike the prior-murder special circumstance was properly denied, we affirm the Court of Appeal’s denial of his petition for a writ of mandate.
I
Defendant Robert Zane Curl is charged in the Fresno County Superior Court with first degree murder. A prior-murder special circumstance is alleged. (Pen. Code, § 190.2, subd. (a)(2)—all further statutory references are to the Penal Code unless otherwise indicated.) By pretrial motion defendant sought to strike the prior-murder special-circumstance allegation on grounds that he was under the influence of drugs at the time he pled guilty to the 1977 murder of an inmate at the California Medical Facility in Vacaville, and that he was not properly advised of his Boykin-Tahl rights (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]) at the time he entered his guilty plea.
The trial court held an evidentiary hearing on the motion. No transcript of the 1977 change-of-plea proceedings was available, but the minute order for those proceedings reflects that counsel reached a stipulated plea of second degree murder. It further states: “Counsel and Court now voir dire defendant as to the charge, whereupon the change of plea is granted. Having considered the transcript of proceedings had in the lower court, the Court finds the pleas to be free and voluntary, predicated on a factual basis, with an intelligent waiver of rights and with understanding of the nature of the charges and possible consequences and the plea is accepted.”
[1297]*1297The trial judge who presided over the change-of-plea proceedings on July 1, 1977, the prosecutor, and counsel who represented defendant in those proceedings, each testified at the evidentiary hearing.
The trial judge, now retired, had no specific recollection of the proceedings at which defendant pleaded guilty to second degree murder, nor could he specifically recall defendant. He testified, however, that it was his regular custom and habit to assure that either he or counsel completely reviewed the waiver of constitutional trial rights with a defendant who was entering a guilty plea, and that he would not have accepted such a plea if any of the answers obtained in questioning the defendant was not satisfactory.1
The prosecutor who represented the People at the 1977 change-of-plea proceedings specifically recalled defendant and those proceedings, and testified that defendant had been advised of and waived his Boykin-Tahl rights. The prosecutor could not recall with certainty whether the potential term of imprisonment was discussed,2 or who had advised defendant of his rights. Although he had not seen defendant display any objective signs of intoxication, the prosecutor acknowledged that there was a drug problem at Vacaville during the time period in question. It was further established that the prosecutor’s file in the prior murder case contained a notation that there was a “full voir dire by the Court and counsel” at the change-of-plea proceedings. The prosecutor testified he would not have made this notation had defendant not been questioned about recent drug ingestion.
Counsel who represented defendant at the change-of-plea proceedings testified he had some memory of the case but could not remember any particulars. He too testified it was his custom and habit either to have his client complete a written waiver form, or to go over each constitutional [1298]*1298right that his client was waiving by entry of a guilty plea prior to such proceedings. It was also his custom and habit to assess whether his client was under the influence of alcohol or drugs at the time of entering a plea, to advise his client of the future consequences of pleading guilty, and to voir dire him concerning the rights he was waiving by entering a guilty plea. Counsel testified he would not agree to the acceptance and entry of a guilty plea unless his client had specifically waived each of his constitutional trial rights (right to jury trial, confrontation, and privilege against self-incrimination).
Defendant testified in his own behalf at the hearing on the motion to strike the prior-murder special circumstance. He acknowledged having participated in the change-of-plea proceedings on July 1, 1977. At that time he understood he was to receive a six-year concurrent term, believing that would not affect him in the future. He claimed he took drugs every day while incarcerated at Vacaville and was under the influence of some substance all the time. He further claimed he was never advised of his constitutional trial rights and asserted he would not have pled guilty to second degree murder had he been so advised.
At the conclusion of the hearing, the trial court ruled that the People had met their initial burden of establishing the fact that defendant had suffered the 1977 conviction by producing a certified copy of the abstract of judgment for that conviction. The court reasoned that the burden thereafter “shifted” to defendant who, by his testimony, had made an adequate showing of constitutional infirmity so as to “shift the burden back” upon the People to rebut defendant’s evidence and establish the constitutional validity of the prior conviction. The court concluded the People had met this alleged burden by “clear and convincing evidence,” but indicated further it would not have made such a finding were the applicable standard “proof beyond a reasonable doubt.”
Defendant petitioned the Court of Appeal for a writ of mandate. In denying the petition, that court reasoned as follows: (1) both the defendant and the People have a statutory right to have a prior-murder special-circumstance allegation “decided” by the same jury that sits as the trier of fact of defendant’s guilt of the instant murder; (2) this statutory right encompasses the right to a jury trial on a collateral challenge to the constitutional validity of the underlying prior murder conviction; (3) as such, absent a waiver by both sides of their respective right to jury trial on the validity of the special circumstance allegation, the only pretrial procedure that will “protect[] the defendant from the consequences of an unwarranted special circumstance trial,” “while preserving to the People their statutory right[s],” is one “equivalent [to] a Penal Code section 995 motion,” and as [1299]*1299such the court must decide the pretrial challenge based on whether or not “reasonable cause” has been shown to bind the defendant over for trial on the special circumstance allegation. The Court of Appeal concluded: “We deem the motion made below to be the equivalent of a Penal Code section 995 motion. Because the court utilized a standard [(clear and convincing evidence)] much higher than ‘reasonable cause’ to bind the defendant over for trial on the special circumstance, a new hearing on this issue is unnecessary.”
Both parties sought review in this court; we granted their respective petitions. The State Public Defender has filed an amicus curiae brief on behalf of defendant; the Criminal Justice Legal Foundation has filed an amicus curiae brief on behalf of the People.
II
We must first determine whether the defendant’s and the People’s statutory right to a jury trial on the truth of a prior-murder special-circumstance allegation (§ 190.4, subd. (a)) also encompasses the right to a jury trial on a collateral challenge to the constitutional validity of the underlying prior conviction. We conclude that it does not.
Section 190.1, subdivision (a), commands that the trier of fact shall determine the truth of all charged special-circumstance allegations at the same time as adjudication of the question of defendant’s guilt of the murder charge.3 The statute creates an exception for prior-murder special circumstances.
Section 190.1, subdivision (b), provides that, in those instances where a prior-murder special circumstance is alleged, there shall be separate “further proceedings” to determine the truth of that special circumstance allegation.4
Section 190.4, subdivision (a), provides, in pertinent part: “Whenever special circumstances as enumerated in Section 190.2 are alleged and the [1300]*1300trier of fact finds the defendant guilty of first degree murder, the trier of fact shall also make a special finding on the truth of each alleged special circumstance. The determination of the truth of any or all of the special circumstances shall be made by the trier of fact on the evidence presented at the trial or at the hearing held pursuant to Subdivision (b) of Section 190.1.” (Italics added.)
In determining the meaning of these controlling statutory provisions, we are guided by well-settled principles. We look first to the language of the statute itself. (E.g., People v. Craft (1986) 41 Cal.3d 554, 559 [224 Cal.Rptr. 626, 715 P.2d 585]; People v. Knowles (1950) 35 Cal.2d 175, 182 [217 P.2d 1].) When the language is clear and there is accordingly no uncertainty as to the legislative intent, we look no further. (E.g., People v. Weidert (1985) 39 Cal.3d 836, 843 [218 Cal.Rptr. 57, 705 P.2d 380]; People v. Belleci (1979) 24 Cal.3d 879, 884 [157 Cal.Rptr. 503, 598 P.2d 473].) In such a case we do no more than enforce the statute according to the plain meaning of its terms. (Leroy T. v. Workmen’s Comp. Appeals Bd. (1974) 12 Cal.3d 434, 438 [115 Cal.Rptr. 761, 525 P.2d 665]; accord Caminetti v. United States (1917) 242 U.S. 470, 485 [61 L.Ed. 442, 452, 37 S.Ct. 192].)
These rules of statutory construction are applicable whether the measure is enacted by the Legislature through the regular lawmaking process or, as with the provisions of our current death penalty statute, by the electorate through the initiative process. (See In re Lance W. (1985) 37 Cal.3d 873, 886-890 [210 Cal.Rptr. 631, 694 P.2d 744].)
When the provisions of sections 190.1, subdivisions (a) and (b), and section 190.4, subdivision (a), are read as a whole, it is clear that the statutory scheme governing capital murder prosecutions grounded on the prior-murder special circumstance neither expressly, nor impliedly, requires that a collateral attack upon the constitutional validity of the underlying prior conviction be heard by the trier of fact.5
[1301]*1301The meaning of the phrase “the truth of such special circumstance,” as utilized in section 190.1, is plain and clear to us: The jury sitting as trier of fact must determine “the truth of” the prior conviction—i.e., the fact that defendant was previously convicted of first or second degree murder. This court has on past occasions utilized the phrase “the truth of [prior convictions]” in just this very context. (See, e.g., In re Yurko (1974) 10 Cal.3d 857, 863 [112 Cal.Rptr. 513, 519 P.2d 561]; People v. Curtis (1969) 70 Cal.2d 347, 360, fn. 10 [74 Cal.Rptr. 713, 450 P.2d 33].)
Section 190.4, subdivision (a), provides that, “[t]he determination of the truth of any or all of the special circumstances shall be made by the trier of fact on the evidence presented at the trial or at the hearing held pursuant to Subdivision (b) of Section 190.1.” (Italics added.) The phrase “hearing held pursuant to Subdivision (b) of Section 190.1” is an obvious reference to the bifurcated proceeding which follows a verdict of guilt when a prior murder special circumstance has been alleged. (§ 190.1, subd. (b).) Like the determination of “the truth of” all other special circumstances, a determination of “the truth of” a prior-murder special circumstance based on evidence presented at the bifurcated proceeding is factual in nature; the jury must find proof beyond a reasonable doubt of the existence of the prior conviction. Such a construction of sections 190.1, subdivision (b), and 190.4, subdivision (a), renders the meaning of the statutory language (“the truth of any or all of the special circumstances”) consistent throughout all relevant provisions of the statutory scheme. (People v. McCart (1982) 32 Cal.3d 338, 344 [185 Cal.Rptr. 284, 649 P.2d 926]; Stillwell v. State Bar (1946) 29 Cal.2d 119, 123 [173 P.2d 313].)6
[1302]*1302There are also practical policy considerations favoring pretrial adjudication of collateral attacks upon the constitutional validity of prior convictions. As this court stated over 20 years ago: “A jury can no more be expected to disregard a ‘true’ prior conviction because of its unconstitutionality than it can be expected to disregard a confession because it was technically invalid. California policy clearly requires the question of the constitutionality of a prior conviction to be determined by the court and not by the jury.” (People v. Curtis, supra, 70 Cal.2d at p. 360; see also Jackson v. Denno (1964) 378 U.S. 368 [12 L.Ed.2d 908, 84 S.Ct. 1774, 1 A.L.R.3d 1205].) And in People v. Coffey, supra, 67 Cal.2d at page 215, we observed: “It is clearly in the interest of efficient judicial administration that attacks upon the constitutional basis of prior convictions be disposed of at the earliest possible opportunity, and we are therefore of the view that, if the issue is properly raised at or prior to trial, it must be determined by the trial court.”
As already shown, the statutory provisions which control here provide for bifurcated guilt and special circumstance phases when a prior-murder special circumstance is alleged, and they require that the existence of the prior conviction be determined by the trier of fact only after a verdict of guilt has been returned on the instant murder charge. As Justice Baxter observed in his separate concurring opinion below, “It would be extremely difficult for a jury to dispassionately adjudicate the constitutional validity of a defendant’s prior murder conviction after having found him guilty of first degree murder and being made aware of the fact of the prior murder conviction.”
We conclude that the Court of Appeal plainly erred in its determination that the statutory right to a jury trial on the truth or existence of a prior-murder special circumstance also encompasses the right to a jury trial on a collateral challenge to the constitutional validity of the underlying prior conviction.
[1303]*1303III
We have further determined, consistent with a long line of settled authority, that when a defendant seeks to collaterally attack the validity of a prior murder conviction alleged as a prior-murder special circumstance, the defendant has the burden of proof in establishing the constitutional invalidity of the prior conviction.
A collateral challenge to the constitutional validity of a prior conviction—i.e., a claim that, upon entry of a guilty plea to the prior murder charge, the defendant was not admonished and did not knowingly or effectively waive his constitutional “Boykin-Tahr’ rights (Boykin v. Alabama, supra, 395 U.S. 238; In re Tahl, supra, 1 Cal.3d 122), or a claim that he was under the influence of some substance which rendered his waiver of rights and entry of the plea involuntary and constitutionally defective— presents legal questions of a far different nature than the factual determination of the existence of the prior conviction. Our Legislature has established certain threshold presumptions that apply to such collateral proceedings: the presumption “that official duty has been regularly performed” (Evid. Code, § 664); that a court whose judgment is under collateral attack “acted in the lawful exercise of its jurisdiction” (Evid. Code, § 666); and the provision that the “burden of producing evidence as to a particular fact is initially on the party with the burden of proof as to that fact.” (Evid. Code, § 550, subd. (b).)
By operation of these presumptions, the prior murder conviction whose validity defendant has contested is presumptively valid, and he bore the burden of proving its constitutional invalidity below. In a long line of settled authority traceable to the United States Supreme Court’s seminal opinion in Johnson v. Zerbst (1938) 304 U.S. 458 [82 L.Ed. 1461, 58 S.Ct. 1019, 146 A.L.R. 357], it has been recognized (often in the context of waiver of the right to counsel in pre-Boykin cases) that “[w]hen collaterally attacked, the judgment of a court carries with it a presumption of regularity,” and that on collateral attack “the burden of proof rests upon [the defendant] to establish that he did not competently and intelligently waive his constitutional right[s] . . . .” (Johnson v. Zerbst, supra, 304 U.S. at pp. 468-469 [82 L.Ed. at p. 1469], fns. omitted; see, e.g., Moore v. Michigan (1957) 355 U.S. 155 [2 L.Ed.2d 167, 78 S.Ct. 191]; Brown v. Allen (1953) 344 U.S. 443, 458, fn. 6 [97 L.Ed. 469, 489, 73 S.Ct. 397]; Darr v. Burford (1950) 339 U.S. 200, 218 [94 L.Ed. 761, 774-775, 70 S.Ct. 587], overruled on other grounds in Fay v. Noia (1963) 372 U.S. 391, 435 [9 L.Ed.2d 837, 866-867, 83 S.Ct. 822]; Hawk v. Olsen (1945) 326 U.S. 271, 279 [90 L.Ed. 61, 67, 66 S.Ct. 116]; Walker v. Johnston (1941) 312 U.S. 275, 286 [85 L.Ed. 830, 835-836, 61 S.Ct. 574].) This court has likewise long followed the rule of Johnson v. [1304]*1304Zerbst. (See, e.g., In re Berry (1955) 43 Cal.2d 838, 846 [279 P.2d 18]; In re Dixon (1953) 41 Cal.2d 756, 760 [264 P.2d 513]; In re Connor (1940) 16 Cal.2d 701, 707 [108 P.2d 10] [quoting the Johnson v. Zerbst language on the burden of proof].)
As was stated by the high court in Darr v. Burford, supra, 339 U.S. 200, “A conviction after public trial in a state court by verdict or plea of guilty places the burden on the accused to allege and prove primary facts, not inferences, that show, notwithstanding the strong presumption of constitutional regularity in state judicial proceedings, that in his prosecution the state so departed from constitutional requirements as to justify a federal court’s intervention to protect the rights of the accused.” (Id., at p. 218 [94 L.Ed. at pp. 774-775], fn. omitted, italics added.)7
Here, defendant testified that he was under the influence of drugs when he entered his guilty plea to the 1977 murder, and that he was not advised of his Boykin-Tahl rights at the time of that plea. In rebuttal, the People introduced substantial evidence at the evidentiary hearing below, as was their right. (People v. Sumstine, supra, 36 Cal.3d at p. 924, fn. 10.) All interested parties present at the prior change-of-plea proceedings testified at the hearing. That testimony amply supports the trial court’s finding that defendant was fully admonished and knowingly waived each of his [1305]*1305Boykin-Tahl rights, and that he freely and voluntarily entered his guilty plea to second degree murder.
We conclude that the Court of Appeal erred in its determination that the People had the burden of proof to establish the “constitutional validity” of the prior murder conviction below. On a collateral challenge to the validity of a prior murder conviction via a motion to strike the prior-murder special-circumstance allegation, the defendant must bear the burden of proving the constitutional invalidity of his prior conviction in order to prevail on the motion.
IV
The Court of Appeal construed the relevant statutory provisions as requiring that the People prove the “constitutional validity” of the prior murder conviction to the trier of fact “beyond a reasonable doubt.” Thus far we have shown that this analysis was flawed in two respects: it is the defendant who bears the burden of establishing the constitutional invalidity of the prior conviction on collateral attack, and such a determination must be made by the court prior to trial and at the conclusion of an evidentiary hearing on the motion to strike the prior-murder special circumstance. The Court of Appeal’s further conclusion that the “beyond a reasonable doubt” standard of proof applied here was also error.
While section 190.4, subdivision (a), expressly provides that the People have the burden of proving “the truth of” the prior murder conviction by the heightened “beyond a reasonable doubt” standard of proof, the statutory scheme makes no express provision for the standard of proof to be applied to a pretrial determination of the constitutional validity of the prior conviction. In the absence of such express provision, Evidence Code section 115 controls. It provides, in relevant part: “Except as otherwise provided by law, the burden of proof requires proof by a preponderance of the evidence.”
Analogous case law lends persuasive support to our conclusion that the “preponderance of the evidence” standard of proof embodied in Evidence Code section 115 is the applicable standard for establishing the invalidity of the prior murder conviction. Correctly construed, petitioner’s pretrial motion to strike the prior-murder special-circumstance allegation required the trial court to determine preliminary factual questions relating to the validity of the prior murder conviction—i.e., whether defendant was under the influence of narcotics when he entered his guilty plea, and whether he was admonished per Boykin-Tahl and expressly waived his constitutional trial rights. The “preponderance of the evidence” standard of proof has been [1306]*1306applied by the high court, and by this court, to such closely related constitutional questions as the voluntariness of confessions (see Lego v. Twomey (1972) 404 U.S. 477 [30 L.Ed.2d 618, 92 S.Ct. 619]; People v. Markham (1989) 49 Cal.3d 63 [260 Cal.Rptr. 273, 775 P.2d 1042]) and the admissibility of evidence challenged on Fourth Amendment grounds. (See Colorado v. Connelly (1986) 479 U.S. 157 [93 L.Ed.2d 473, 107 S.Ct. 515].) Indeed, in Johnson v. Zerbst, supra, 304 U.S. 458, wherein the defendant, in a habeas corpus proceeding, was seeking to collaterally attack the validity of his prior conviction on grounds that he did not competently and intelligently waive his constitutional right to counsel, the high court expressly held that the burden of proof rested with the defendant to establish the same by a preponderance of the evidence. (Id., pp. 468-469 [82 L.Ed. at pp. 1468-1469].)8
V
In conclusion, when a defendant seeks to collaterally attack the validity of a prior conviction underlying a prior-murder special circumstance, he must first allege facts sufficient to justify a hearing on his motion to strike the special circumstance—i.e., “allege actual denial of his constitutional rights.” (People v. Sumstine, supra, 36 Cal.3d at p. 922.) The court shall thereupon conduct an evidentiary hearing in the manner set forth in Coffey and Sumstine. At the hearing the People initially have the burden of producing evidence of the prior murder conviction sufficient to make a prima facie showing that defendant in fact suffered the conviction; the [1307]*1307prosecution will ultimately bear the full burden of proving the existence of the prior conviction beyond a reasonable doubt at the bifurcated proceeding following the guilt phase. (§ 190.1, subd. (b).) Once this prima facie showing has been made, the defendant has the burden of producing evidence to establish the constitutional invalidity of the prior conviction, and the burden of proof on such issue shall remain with the defendant. The People have the further right to present evidence in rebuttal. (People v. Sumstine, supra, 36 Cal.3d at p. 923; People v. Coffey, supra, 67 Cal.2d at p. 217.) At the conclusion of the hearing, the trial court must determine whether the defendant has carried his burden of establishing the constitutional invalidity of the prior conviction by a preponderance of the evidence. (Evid. Code, § H5.)
The decision of the Court of Appeal denying the petition for writ of mandate is affirmed.
Lucas, C. J., Panelli, J., Kennard, J., and Arabian, J., concurred.