THE PEOPLE, Plaintiff and Respondent, v. CHARLES G. POKOVICH, Defendant and Appellant, 39 Cal. 4th 1240

Opinion KENNARD, J. May a testifying defendant be impeached at trial with statements made before trial to mental health professionals during a court-ordered examination to determine the defendant’s mental competency to stand trial? We conclude that such impeachment violates the federal Constitution’s privilege against self-incrimination. I On March 31, 2002, at approximately 3:00 p.m., bullets hit three moving vehicles on Iron Mountain Road near Keswick, Shasta County.

Around the same time, bullets hit another car, occupied by Joyce Muse and her fiancé, Lawrence Taylor, going down the driveway at the home of Muse’s parents, who lived across from defendant Charles G. Pokovich on Iron Mountain Road. Taylor saw defendant standing across the street with a rifle; defendant yelled at Taylor and Muse to get off his property. After receiving telephone calls reporting the shootings, Shasta County Sheriff deputies set up roadblocks in the area. Defendant came up to them and said he might be the person they were looking for because Joyce Muse appeared to believe that he had shot at her.

He consented to a search of his mobilehome. Found inside were a rifle and ammunition; in addition, five shell casings that matched defendant’s rifle were retrieved from an area in front of the home. A bullet fragment recovered from one of the cars hit earlier matched the ammunition and the rifle recovered from defendant’s home. Defendant was charged with four counts of shooting at an occupied vehicle (Pen. Code, § 246) and eight counts of assault with a firearm (§ 245, subd. (a)(2)).

It was also alleged that he personally used a firearm. (§ 12022.5, subd. (a).) On April 22, 2002, one day before the preliminary hearing was to be held, defense counsel expressed to the trial court his concern about defendant’s mental competence to stand trial (§ 1368, subd. (b)), based on “certain of his conduct which would indicate hallucinations, that there’s a certain lack of reality . . . .” The court suspended criminal proceedings and appointed two mental health professionals—Dr. Aravind K. Pai, a psychiatrist, and Dr. Kent R.

Caruso, a licensed psychologist—to examine defendant. (§ 1369.) Both did so; their written reports to the trial court expressed their view that defendant was competent to stand trial. The defense waived the right to a jury trial on the issue (§ 1369) and submitted the matter to the court based on the reports of the mental health experts. The court ruled that defendant was competent to stand trial. Defendant testified at trial.

On direct examination by his attorney, he said that around 10:00 o’clock on the morning of the shootings he fired shots from his .22-caliber rifle to scare blue jays from the trees on his property. At 3:00 o’clock that afternoon, he went out on his porch because he heard a car come down the Muses’ driveway. Defendant saw Joyce Muse get out of a car; she yelled that she was calling the police. Defendant described Muse as an intimidating person who on occasion was loud and obnoxious. On cross-examination by the prosecutor, defendant denied drinking any alcohol the day of the shooting.

During a recess, the trial court discussed a statement the prosecutor had made earlier at a bench conference. In that statement, the prosecutor announced an intention to impeach defendant with inconsistent statements defendant had made earlier to the two court-appointed mental health professionals during the competency evaluations. The court told the prosecutor to provide the court and defense counsel with citations of authority to support the claim that defendant could be impeached with the statements in question. The case was continued to the next morning.

At that time, over defendant’s objection, the trial court ruled that the prosecution could use the statements to impeach defendant. When the prosecutor resumed the cross-examination, defendant admitted that, during the competency examination, he had told Dr. Pai that he drank two cans of beer the day of the shootings and that he got along with Joyce Muse and his other neighbors; defendant also testified he had not told Dr. Caruso that he was shooting at blue jays and rabbits on the day in question. Dr.

Caruso, called as a rebuttal witness by the prosecution, then testified that during the competency evaluation defendant told him he was aware of multiple shots being fired at cars from the direction of his property at the time defendant claimed he was shooting at blue jays and rabbits. The jury convicted defendant of all charges and found true the allegation that he personally used a firearm in committing the assaults. The trial court sentenced defendant to an aggregate term of 16 years 4 months in prison.

The Court of Appeal affirmed, holding that a testifying defendant may be impeached at trial with statements made to mental health professionals during a pretrial competency evaluation. Defendant petitioned this court for review, noting the long-standing conflict in decisions of the Courts of Appeal on this issue. (Compare People v. Stanfill (1986) 184 Cal.App.3d 577, 581 [229 Cal.Rptr. 215] [statements may be used to impeach] with People v. Harris (1987) 192 Cal.App.3d 943, 949 [237 Cal.Rptr. 747] [statements may not be used to impeach] and Baqleh v.

Superior Court (2002) 100 Cal.App.4th 478, 499, fn. 5 [122 Cal.Rptr.2d 673] [citing Harris with approval].) We granted review. II Defendant contends the trial court violated his constitutional privilege against self-incrimination (U.S. Const., 5th Amend.) when it allowed the prosecution to impeach him at trial with statements he had made to the two court-appointed mental health professionals who were to determine his competency to stand trial. He argues that his statements were legislatively compelled and therefore could not be used either as substantive evidence of his guilt or for the purpose of impeaching him.

Our Legislature has declared that a “person cannot be tried or adjudged to punishment while that person is mentally incompetent.” (§ 1367, subd. (a); see Pate v. Robinson (1966) 383 U.S. 375, 378 [15 L.Ed.2d 815, 86 S.Ct. 836] [conviction of legally incompetent person violates due process]; People v.

Perry (1939) 14 Cal.2d 387, 397-399 [94 P.2d 559] [§ 1367 codifies common law rule].) If the trial court has a doubt about the mental competency of a defendant, whether arising from the court’s own observation or that of counsel, it must suspend the criminal proceeding and appoint a licensed psychiatrist or a licensed psychologist and any other expert the court considers appropriate to examine the defendant to determine the nature of the defendant’s mental disorder, if any. (§§ 1368, 1369.) Thus, competency proceedings are initiated by the trial court, not the defendant.

The defendant cannot refuse to undergo a psychiatric examination and cannot waive the right to a trial on the issue of competency. (Centeno v. Superior Court (2004) 117 Cal.App.4th 30, 43 [11 Cal.Rptr.3d 533].) Because our statutory scheme governing competency to stand trial does not give the defendant the right to refuse to submit to the competency examination, it implicates a defendant’s federal constitutional privilege against self-incrimination. (U.S. Const., 5th Amend.) Pertinent here is the Court of Appeal’s decision in Tarantino v. Superior Court (1975) 48 Cal.App.3d 465 [122 Cal.Rptr. 61] (Tarantino).

There, the court balanced the state’s need for accurate competency evaluations against the need for safeguarding the accused’s constitutional right against self-incrimination. Tarantino judicially declared a rule of immunity for statements made by a defendant to a mental health professional during a competency examination: “[N]either the statements of [the defendant] to the psychiatrists appointed under

section 1369 nor the fruits of such statements may be used in trial of the issue of [the defendant’s] guilt, under either the plea of not guilty or that of not guilty by reason of insanity.” (Id. at p. 470.) Six years later, in Estelle v.

Smith (1981) 451 U.S. 454 [68 L.Ed.2d 359, 101 S.Ct. 1866] (Estelle), the United States Supreme Court held that a “criminal defendant, who neither initiates a psychiatric evaluation nor attempts to introduce any psychiatric evidence, may not be compelled to respond to a psychiatrist if his statements can be used against him at a capital sentencing proceeding” unless the defendant had been informed of and waived his rights under Miranda v.

Arizona (1966) 384 U.S. 436 [16 L.Ed.2d 694, 86 S.Ct. 1602] (Miranda). (Estelle, supra, 451 U.S. at pp. 468-469.) If the defendant invokes his rights and refuses to answer questions of the mental health professional conducting the competency examination, “the validly ordered competency examination nevertheless could . . . proceed[] upon the condition that the results would be applied solely for that purpose,” that is, solely for the purpose of the competency examination. (Id. at p. 469.) The next year, this court in People v.

Arcega (1982) 32 Cal.3d 504, 522 [186 Cal.Rptr. 94, 651 P.2d 338], adopted the immunity rule the Court of Appeal had articulated in Tarantino, supra, 48 Cal.App.3d at page 470. Immunity is necessary, we said, to “ensure that an accused is not convicted by use of his own statements made at a court-compelled examination,” and to foster “honesty and lack of restraint on the accused’s part at the examination and thus promote[s] accuracy in the psychiatric evaluation.” (People v. Arcega, supra, 32 Cal.3d at p. 522; see People v.

Weaver (2001) 26 Cal.4th 876, 960 [111 Cal.Rptr.2d 2, 29 P.3d 103].) Those decisions establish that the Fifth Amendment’s privilege against self-incrimination applies to competency examinations, and therefore a defendant’s statements made during such an examination may not be used by the prosecution to prove its case-in-chief as to either guilt or penalty. But those decisions do not directly answer the question presented here: May statements a defendant has made during a court-initiated mental competency examination later be used to impeach the defendant if he or she testifies at trial?

A number of decisions have held that notwithstanding the existence of a constitutional or other legal impediment barring the prosecution from introducing certain evidence to establish a defendant’s guilt, the evidence may be used to impeach a testifying defendant. (See, e.g., Harris v. New York (1971) 401 U.S. 222, 225 [28 L.Ed.2d 1, 91 S.Ct. 643] [statements obtained in violation of Miranda]; Walder v. United States (1954) 347 U.S. 62, 65 [98 L.Ed. 503, 74 S.Ct. 354] [evidence obtained in violation of the Fourth Amendment]; People v.

May (1988) 44 Cal.3d 309, 315 [243 Cal.Rptr. 369, 748 P.2d 307] (May) [statements obtained in violation of Miranda]; People v. Coleman (1975) 13 Cal.3d 867, 889 [120 Cal.Rptr. 384, 533 P.2d 1024] [probationer’s testimony at probation revocation hearing]; People v.

Crow (1994) 28 Cal.App.4th 440, 452 [33 Cal.Rptr.2d 624] [statements made during plea negotiations].) Defendant here distinguishes those cases, asserting that, unlike his case, the defendant’s statements in each of those cases were not “legislatively compelled.” Statements that are legislatively compelled, defendant argues, implicate the Fifth Amendment’s privilege against self-incrimination. In support, defendant cites the United States Supreme Court’s decision in New Jersey v.

Portash (1979) 440 U.S. 450 [59 L.Ed.2d 501, 99 S.Ct. 1292] (Portash), and this court’s decisions in May, supra, 44 Cal.3d 309, and People v. Macias (1997) 16 Cal.4th 739 [66 Cal.Rptr.2d 659, 941 P.2d 838] (Macias). We summarize those cases below. In Portash, the defendant, who was a public employee, testified before a New Jersey grand jury.

A New Jersey statute provided that the testimony of a public employee before a grand jury “ ‘shall not be used against such public employee in a subsequent criminal proceeding . . . .’ ” (Portash, supra, 440 U.S. at p. 452, fn. 1.) At the defendant’s later trial for extortion, the trial court ruled that the prosecution could use the defendant’s grand jury testimony to impeach him if he testified at trial. The defendant chose not to testify.

The United States Supreme Court in Portash said that “[tjestimony given in response to a grant of legislative immunity is the essence of coerced testimony.” (Portash, supra, 440 U.S. at p. 459.) Observing that the “witness is told to talk or face the government’s coercive sanctions, notably, a conviction for contempt,” the court held that the defendant’s statements before the grand jury were compulsory and therefore inadmissible for impeachment. (Ibid.) The court found a “crucial distinction” between statements made in that situation and statements obtained in violation of Miranda warnings, explaining that statements taken in violation of Miranda are not coerced or involuntary and that judicial decisions allowing their use to impeach a defendant’s testimony at trial (Oregon v.

Hass (1975) 420 U.S. 714 [43 L.Ed.2d 570, 95 S.Ct. 1215]; Harris v. New York, supra, 401 U.S. 222) were based on balancing the competing interests of deterring unlawful police conduct and the need to prevent perjury in testimony. (Portash, supra, 440 U.S. at pp. 458-159.) With respect to this court’s decision in May, supra, 44 Cal.3d at page 311, we there concluded that the California electorate’s passage of Proposition 8, through its “Truth-in-Evidence” provision (Cal. Const., art. I, § 28, subd. (d)), abrogated our prior decision in People v.

Disbrow (1976) 16 Cal.3d 101 [127 Cal.Rptr. 360, 545 P.2d 272], which had held that a defendant’s statements obtained in violation of Miranda v. Arizona, supra, 384 U.S. 436, were inadmissible for impeachment. Citing the United States Supreme Court’s contrary holding in Harris v. New York, supra, 401 U.S. 222 (voluntary statements obtained in violation of Miranda are admissible to impeach a testifying defendant), we held in May that, in light of Proposition 8, the high court’s decision in Harris v.

New York must be followed in California. (May, supra, 44 Cal.3d at pp. 311, 318.) Thereafter, citing Portash, supra, 440 U.S. 450, this court in May observed that “[legislatively compelled testimony [cannot] be used against the testifier for any purpose under the federal Constitution” (May, supra, 44 Cal.3d at p. 317).

As to our decision in Macias, supra, 16 Cal.4th 739, there a majority of this court concluded that a minor defendant’s statements to a probation officer in an interview in preparation for a hearing to determine whether the minor should be tried as an adult were not compelled and therefore could be used for impeachment, as there was no violation of the juvenile’s privilege against self-incrimination. (Id. at p. 756 (plur. opn. of Chin, J.); id. at p. 757 (cone, opn. of Baxter, J.); see also People v.

Humiston (1993) 20 Cal.App.4th 460, 472-476 [24 Cal.Rptr.2d 515].) The plurality pointed out that no statute required the minor to speak to the probation officer, that the minor had alternative methods of providing mitigating evidence to the probation officer, that the minor’s statements were generally made with counsel present, and that a probation officer is less likely to overreach in a fitness interview than a police officer in a custodial setting. (Macias, supra, 16 Cal.4th at pp. 752, 756.) Turning to the high court’s decision in Portash, supra, 440 U.S. 450, the Macias plurality observed: “Portash forbids the use in any criminal trial of involuntary statements that a defendant gave following a use immunity grant.

But we do not believe Portash prohibits the limited use of statements made to a probation officer in preparation for a juvenile fitness hearing to impeach the same minor defendant’s voluntary, inconsistent trial statements.” (Macias, supra, 16 Cal.4th at p. 754.) The Macias plurality went on to note that the high court itself “has recognized that Portash was a unique and limited case” involving coerced testimony, because there the witness was ordered to testify or face contempt sanctions. (Id. at pp. 754-755.) The Macias plurality then cited the high court’s decision in South Dakota v.

Neville (1983) 459 U.S. 553, 563-564 [74 L.Ed.2d 748, 103 S.Ct. 916], for the proposition that a defendant’s decision whether to take a blood-alcohol test was not legislatively compelled unless the defendant “could show that the consequences of his decision either to submit or to refuse the request were so severe as to remove effectively his free will to choose.” (Macias, supra, 16 Cal.4th at p. 755.) The Macias plurality also cited the high court’s decision in Minnesota v.

Murphy (1984) 465 U.S. 420, 431-435 [79 L.Ed.2d 409, 104 S.Ct. 1136], which stated that a probationary defendant’s obligation to answer questions from his probation officer truthfully did not convert the answers into compelled statements. (Macias, supra, 16 Cal.4th at p. 755.) Defendant here is right that compelled statements may not be used by the prosecution for any purpose. (Portash, supra, 440 U.S. at p. 459.) But defendant is wrong insofar as he assumes that whenever a procedure is legislatively required, any statements made in that context are compelled and therefore any use of them by the prosecution would violate the Fifth Amendment’s privilege against self-incrimination.

Statements a defendant makes during a competency examination under the statutory procedure the Legislature established in sections 1368 and 1369 are in some respects similar to but in other respects different from those at issue in the high court’s decision in Portash, supra, 440 U.S. 450, and in this court’s decision in Macias, supra, 16 Cal.4th 739, as we explain below. The statutory procedure at issue here is similar to that involved in Portash, supra, 440 U.S. 450, in that both require the defendant to submit to an examination, here a mental competency examination and in Portash a grand jury examination.

But unlike the New Jersey statute in Portash, which compelled the witness to testify before the grand jury (Portash, supra, 440 U.S. at p. 452, fn. 1), the statements a defendant makes in a mental competency examination are not compelled. Although under our statutory scheme a defendant must submit to a court-initiated competency evaluation, there is no compulsion to make any statements. The parties have not cited, nor has our research disclosed, the existence of any legal sanction against a defendant who refuses to speak to, or cooperate with, the court-appointed mental health experts. (See People v.

Harris, supra, 192 Cal.App.3d at pp. 946-947 [competency trial held after the defendant’s refusal to be interviewed by mental health professionals]; Tarantino, supra, 48 Cal.App.3d at pp. 468, 471 [contempt order for refusing to be examined without counsel present permanently stayed].) Thus, under our statutory scheme any statement a defendant makes during the mental competency evaluation is not compelled, legislatively or otherwise.

With respect to this court’s decision in Macias, supra, 16 Cal.4th 739, which concerned statements of a minor to a probation officer in preparation for a hearing to determine the minor’s fitness to stand trial as an adult, there, as here, no legal sanction attached to a refusal to make any statements during the procedure at issue. But, unlike the interview with the probation officer in Macias, a defendant in a court-initiated mental competency evaluation must submit to such an examination. (Centeno v.

Superior Court, supra, 117 Cal.App.4th at p. 43.) Our conclusion that a defendant’s statements made at a mental competency evaluation are not legislatively or otherwise compelled and therefore not per se inadmissible for any purposes under the high court’s decision in Portash, supra, 440 U.S. 450, does not end the inquiry of whether they may be used to impeach a defendant’s testimony at trial.

As mentioned earlier, a defendant’s statements at a mental competency examination cannot be used later by the prosecution to prove its case-in-chief as to either guilt or penalty. (Estelle, supra, 451 U.S. at pp. 468-69; People v.

Weaver, supra, 26 Cal.4th at pp. 959-960.) Where the United States Supreme Court has permitted impeachment of a testifying defendant with statements inadmissible to prove guilt, the court has used a test that balances the policy supporting the exclusion of such statements to prove guilt against the policy not to countenance perjury. (Portash, supra, 440 U.S. at p. 458 [incremental deterrence of police illegality weighed against policy against perjury]; see James v.

Illinois (1990) 493 U.S. 307, 316-317 [107 L.Ed.2d 676, 110 S.Ct. 648] [potential chill of truth-seeking process by allowing impeachment found to outweigh loss of probative testimony]; United States v. Havens (1980) 446 U.S. 620, 627 [64 L.Ed.2d 559, 100 S.Ct. 1912] [competing interests of exclusionary rule in discouraging police misconduct and impairment of factfinding goal of trial assessed]; Harris v.

New York, supra, 401 U.S. at p. 225 [introduction of reliable evidence to impeach found to further truth-seeking function of trial, while likelihood of encouraging police misconduct considered only speculative possibility].) Here, we must balance the policy interest in deterring and exposing perjury against the policy interest in preserving and enhancing the reliability of mental competency evaluations. The policy against countenancing perjury is strong. (Portash, supra, 440 U.S. at p. 458.) Allowing false testimony to go unchallenged impairs the integrity of the factfinding objective of a trial (United States v.

Havens, supra, 446 U.S. at p. 627), because such testimony hinders or blocks the disclosure of the truth to the trier of fact (see James v. Illinois, supra, 493 U.S. at p. 321). Just as strong, however, is the policy against trying persons who are mentally incompetent.

In the words of the United States Supreme Court: “ ‘Competence to stand trial is rudimentary, for upon it depends the main part of those rights deemed essential to a fair trial, including the right to effective assistance of counsel, the rights to summon, to confront, and to cross-examine witnesses, and the right to testify on one’s own behalf or to remain silent without penalty for doing so.’ ” (Cooper v. Oklahoma (1996) 517 U.S. 348, 354 [134 L.Ed.2d 498, 116 S.Ct. 1373].) The policy that a mentally incompetent person not be subjected to a trial has its roots in our constitutional, statutory, and common law.

It is thus a policy of ancient and venerable origin, founded on the view that to subject the mentally incompetent to trial or to punishment is inhumane and cruel. (Cooper v. Oklahoma, supra, 517 U.S. at p. 356; People v. Perry, supra, 14 Cal.2d at pp. 397-399.) The “sole purpose of [competency proceedings] ‘is the humanitarian desire to assure that one who is mentally unable to defend himself not be tried upon a criminal charge.’ ” (People v.

Harris, supra, 192 Cal.App.3d at pp. 949-950.) A mental competency evaluation seeks to ascertain the defendant’s ability “to understand the nature of the criminal proceedings or to assist counsel in the conduct of a defense in a rational manner.” (§ 1367, subd. (a).) It therefore is ordered only when there is a legitimate concern that the defendant may be substantially mentally impaired.

Unlike those instances where otherwise inadmissible statements are allowed to impeach a testifying defendant (e.g., Macias, supra, 16 Cal.4th at pp. 755-756 [juvenile’s statements during probation officer’s interview in preparation for hearing to determine whether the juvenile should be tried as an adult]; People v. Coleman, supra, 13 Cal.3d at p. 889 [probationer’s statements at probation revocation hearing]; People v.

Drews (1989) 208 Cal.App.3d 1317, 1325-1326 [256 Cal.Rptr. 846] [defendant’s testimony at pretrial hearing on motion to suppress evidence]), during a mental competency examination a defendant does not have the benefit of the presence of counsel.

Indeed, unlike situations where the presence of counsel may contribute to the purpose of the proceeding, such as the inquiry into a juvenile’s behavioral patterns and social history to determine whether the juvenile should be tried as an adult (Macias, supra, 16 Cal.4th at pp. 747, 756), the presence of counsel during a competency examination by mental health professionals may undermine the usefulness of the examination, making it more difficult for the expert examining the defendant to determine whether the defendant is competent. (See Estelle, supra, 451 U.S. at p. 470, fn. 14 [“ ‘an attorney present during the psychiatric interview could contribute little and might seriously disrupt the examination’ ”]; Tarantino, supra, 48 Cal.App.3d at p. 468 [psychiatrists refused to conduct competency examination with defense attorney present].) Also, determining a defendant’s mental competency requires an assessment of the defendant’s ability to understand the nature of the proceedings and to assist counsel in conducting a defense. (§ 1367, subd. (a).) To make this assessment, the mental health expert will want to evaluate the defendant’s ability to discuss the facts of the case, even though the defendant’s guilt of the offense charged is not relevant to the inquiry. (See People v.

Harris, supra, 192 Cal.App.3d at pp. 949-950; Tarantino, supra, 48 Cal.App.3d at p. 469.) If a defendant’s statements during the examination could later be used to impeach the defendant during the criminal trial, the defendant would have a strong incentive not to be forthcoming during the examination, thus undermining the reliability of the competency determination. A rule allowing a defendant to be impeached at trial with statements made during a competency examination would pose a dilemma for defendant’s trial attorney.

A competency examination occurs after the right to counsel has attached, at a critical stage of the proceeding at which counsel’s participation is constitutionally mandated; the examination cannot be conducted without “the assistance of [defendant’s] attorneys in mating the significant decision of whether to submit to the examination and to what end the psychiatrist’s findings could be employed.” (Estelle, supra, 451 U.S. at pp. 470-471.) Counsel would need to explain the risk of impeachment to the possibly mentally impaired defendant and, if that risk was sufficiently grave, might be ethically bound to advise the defendant not to communicate with the court-appointed mental health professionals at all during the examination.

The prosecution’s ability to conduct its own mental evaluation would also be placed in jeopardy. A defendant may be compelled to submit to competency examinations by prosecution experts (Baqleh v. Superior Court, supra, 100 Cal.App.4th at pp. 505-506), but only if the defendant’s statements during the examination are inadmissible for any purpose at trial (id. at pp. 498-499 & fn. 5, 502).

If a defendant’s statements during a competency examination could later be used against him for impeachment at trial, the trial court could not impose any sanctions on a defendant who refused to submit to an examination by prosecution experts.

As we have observed (see fn. 2, ante), the threat of sanctions for refusing to speak would make the defendant’s statements compelled, and the defendant then would have the right to refuse to participate by invoking the Fifth Amendment privilege against self-incrimination. (Portash, supra, 440 U.S. at p. 459 [“defendant’s compelled statements . . . may not be put to any testimonial use whatever against him in a criminal trial”]; Estelle, supra, 451 U.S. at p. 469.) Thus, allowing a defendant’s statements during a competency evaluation to be used for impeachment at trial would seriously impair the mental health expert’s ability to accurately assess the defendant’s mental competency, because the defendant would likely be unwilling to freely discuss the facts of the crime and might well refuse to speak at all.

Impairment of the examination process in turn would seriously compromise the trial court’s ability to fulfill its constitutional and statutory obligation to determine whether a defendant is competent to stand trial. Against this very substantial impairment of the state’s interest in accurately determining whether criminal defendants are mentally competent to stand trial, we must weigh the risk to the truth-seeking function if the prosecution is precluded from impeaching the defendant at trial with inconsistent statements made during competency evaluations.

A mental competency evaluation is concerned with the defendant’s ability to understand the proceeding and assist counsel, and not with the defendant’s guilt of the offense charged. Therefore, a defendant’s statements to the mental health professional are made for a purpose unrelated to the validity of the criminal charge, and in any event those statements may be consistent with the defendant’s later testimony at trial. Moreover, minor inconsistencies may be attributed to the defendant’s mental impairments that prompted the competency inquiry.

In short, the frequency and utility of impeachment at trial with a defendant’s inconsistent statements during a competency examination is speculative. Having considered and weighed the competing interests, we conclude that the impairment of the mental competency evaluation process if impeachment is permitted outweighs the speculative risk to the truth-seeking function of the criminal trial if impeachment is denied.

Accordingly, we conclude that the Fifth Amendment’s privilege against self-incrimination prohibits the prosecution from using at trial, for the purpose of impeachment, statements a defendant has made during a court-ordered mental competency examination. We have considered, but rejected as impractical, an alternate route to essentially the same result.

Instead of simply disallowing impeachment at trial with a defendant’s statements during a competency examination, we could require trial courts to advise the defendant, before the competency examination, of the right to counsel and the right to remain silent. (See Estelle, supra, 451 U.S. at p. 468.) If the defendant invoked those rights, the court could nevertheless order the competency examination to proceed, but any statements the defendant made during the examination could then be used only for the purpose of determining competency. (Ibid.; see fn. 2, ante.) Acting on the advice of counsel, defendants would, we confidently predict, routinely invoke their rights, and thus the end result would be the same—the defendant’s statements dining the competency examination would be inadmissible for impeachment at trial.

Because we see no advantage in these additional procedural steps, we adopt the more direct approach. Moreover, we are reluctant to place our trial courts in the awkward position of advising defendants of their rights to counsel and to remain silent, and then, after the defendants invoke those rights, ordering the defendants to participate in the evaluation and informing them they cannot remain silent.

Our resolution of the issue before us fully protects both a defendant’s Fifth Amendment privilege against self-incrimination and a defendant’s Sixth Amendment right to counsel because the use immunity recognized here adequately safeguards those rights. (Baqleh v. Superior Court, supra, 100 Cal.App.4th at pp. 502-503.) Accordingly, we need not resolve here the difficult question whether counsel would have a right to be present at a court-ordered competency examination if a defendant’s statements during such an examination could later be used against him.

Nor need we determine here whether statements obtained in violation of the right to counsel may be used to impeach a testifying defendant. (See United States v. Ortega (9th Cir. 2000) 203 F.3d 675 [statements may be used to impeach]; United States v. Brown (2d Cir. 1983) 699 F.2d 585 [statements may not be used to impeach]; People v. Brown (1996) 42 Cal.App.4th 461 [49 Cal.Rptr.2d 652] [statements may be used to impeach]; People v.

Harper (1991) 228 Cal.App.3d 843 [279 Cal.Rptr. 204] [statements may not be used to impeach].) The use of statements that defendant made during his mental competency evaluation to impeach his testimony at trial violated defendant’s constitutional right not to incriminate himself. Whether that error prejudiced defendant is explored below. Ill Under Chapman v.

California (1967) 386 U.S. 18, 24 [17 L.Ed.2d 705, 87 S.Ct. 824], a violation of a criminal defendant’s federal constitutional rights requires reversal of the judgment unless the reviewing court determines “beyond a reasonable doubt that the error complained of did not contribute to the verdict.” Applying this standard here, we agree with the Court of Appeal that the violation of defendant’s Fifth Amendment privilege not to incriminate himself did not prejudice defendant. The evidence against defendant was overwhelming.

The bullet fragment taken from one of the victims’ cars matched not only the shell casings found at defendant’s home, but also his rifle. Also, defendant was seen holding his rifle at the time of the car shootings. The extent of defendant’s impeachment at trial with statements he made at his mental health evaluation was minimal. Whether, as defendant told Dr. Pai, he drank one or two cans of beer on the day of the shootings was of little probative value at trial. There was no allegation that alcohol consumption played any

part in the car shootings, and the jury was aware that there was no alcohol in the sample of defendant’s blood drawn two hours after his arrest. The prosecution’s impeachment of defendant with his statement to Dr. Pai, made at the mental competency examination, that he usually got along with Joyce Muse was minimal. It was undermined by defendant’s trial testimony on redirect examination that Muse was intimidating when she was arguing with her parents or with a boyfriend but that she was otherwise congenial. Dr.

Caruso’s testimony that defendant told him at the mental competency evaluation that he knew the shots fired at the cars came from his property at a time when defendant claimed he was shooting at blue jays, is largely cumulative of testimony by one of the sheriff’s deputies. Deputy Sheriff Ronald Smith testified that defendant admitted he was the man they were looking for, that Joyce Muse thought defendant had been shooting at her, and that he had been shooting at blue jays by his house.

In view of the overwhelming evidence of guilt and the insignificant nature of defendant’s mental competence examination statements later used by the prosecution to impeach him, we conclude that, beyond a reasonable doubt, the error in allowing such impeachment did not contribute to the verdict. (Chapman v. California, supra, 386 U.S. at p. 24.) Disposition The judgment of the Court of Appeal is affirmed. George, C. J., Chin, J., and Moreno, J., concurred. Unless otherwise indicated, all further statutory references are to the Penal Code.

The threat of any sanction such as contempt against a defendant for refusing to answer questions of the mental health experts during a competency examination would render the statements made at that examination compelled. In that event, under Portash, supra, 440 U.S. at page 459, the statements could not be used for any purpose at trial.

Blackstone’s Commentaries demonstrate the historical underpinnings of the policy against subjecting a mentally incompetent person to trial. “ ‘Indeed, in the bloody reign of ¡Henry the Eighth, a statute was made, which enacted that if a person, being compos mentis (of sane mind) should commit high treason, and after fall into madness, he might be tried in his absence, and should suffer death, as if he were of perfect memory. But this savage and inhuman law was repealed by the statute 1 and 2 P. and M., c. 10.’ ” (People v.

Perry, supra, 14 Cal.2d at p. 398, quoting 4 Blackstone’s Commentaries 25.) To the extent it is inconsistent with the views expressed herein, People v. Stanfill, supra, 184 Cal.App.3d 577, is disapproved. The concurring and dissenting opinion of Justice Werdegar asserts that the immunity at issue arises from California statutory law, not federal law. From this premise it argues that our decision here should not be founded upon the federal Constitution’s Fifth Amendment privilege against self-incrimination. That view is untenable.

The rule of immunity was first judicially declared in Tarantino, supra, 48 Cal.App.3d at page 469. As this court observed in People v. Arcega, supra, 32 Cal.3d at page 522, “the basis for the Tarantino decision was the constitutional privilege against self-incrimination.” (See, e.g., People v. Jablonski (2006) 37 Cal.4th 774, 802-803 [38 Cal.Rptr.3d 98, 126 P.3d 938] [judicially declared immunity and Fifth Amendment coextensive]; People v.

Weaver, supra, 26 Cal.4th at p. 960 [“the rule of immunity ‘is necessary to ensure that an accused is not convicted by use of his own statements made at a court-compelled examination’ ”].) The concurring and dissenting opinion of Justice Werdegar thus errs in asserting that the judicially declared immunity rule at issue here is based on statutory law. That approach may also violate the “Tmth-in-Evidence” provision of the California Constitution. (Cal. Const., art. I, § 28, subd. (d); see Macias, supra, 16 Cal.4th 739; May, supra, 44 Cal.3d 309; Ramona R. v.

Superior Court (1985) 37 Cal.3d 802 [210 Cal.Rptr. 204, 693 P.2d 789].) Because defendant does not claim that there is a statutory rule of immunity that prohibited the prosecution from using defendant’s statements to a mental health professional during an examination to determine his competency to stand trial for purposes of impeachment, we need not address this question.