I concur in the judgment of affirmance, and in the majority’s conclusion that any error in allowing use of defendant’s statements to court-appointed competency examiners to impeach *1256his trial testimony was harmless by any standard. But I must dissent from the majority’s determination that error occurred when the prosecution was allowed to impeach defendant’s testimony in this fashion.
The majority holds that, even though a defendant is not compelled by California law to speak to court-appointed competency examiners, but does so, is adjudged competent, later elects to testify in his own behalf at his criminal trial, and takes that opportunity to tell the court something different than what he previously told the examiners, it is a violation of the Fifth Amendment of the United States Constitution to use his earlier statements to impeach his testimonial credibility. Moreover, the majority insinuates, the Sixth Amendment may compel a similar result to the extent the defendant’s counsel was not permitted to attend the competency examination itself. I cannot agree.
At the outset, as Justice Werdegar observes, although California’s judicially declared “blanket use immunity” for statements made in a court-ordered competency examination is designed in part to protect the privilege against self-incrimination, it is a creature of state, not federal, law. (Tarantino v. Superior Court (1975) 48 Cal.App.3d 465, 469—470 [122 Cal.Rptr. 61] (Tarantino); see People v. Arcega (1982) 32 Cal.3d 504, 521-523 [186 Cal.Rptr. 94, 651 P.2d 338] (Arcega); cf. Centeno v. Superior Court (2004) 117 Cal.App.4th 30, 43-44 [11 Cal.Rptr.3d 533].) Tarantino characterized the immunity as one “reasonably to be implied from the [statutory] provisions [for determining competency]” (Tarantino, supra, at p. 469), and it has never been squarely premised on the federal Constitution. It has survived the truth-in-evidence provisions of Proposition 8 (see Arcega, supra, at pp. 521-523), presumably under that measure’s express preservation of “existing statutory rule[s] of evidence relating to privilege” (Cal. Const., art. I, § 28, subd. (d); see Evid. Code, § 940; Ramona R. v. Superior Court (1985) 37 Cal.3d 802, 807-808 [210 Cal.Rptr. 204, 693 P.2d 789] (Ramona R.)- see also cone. & dis. opn. of Werdegar, J., post, at pp. 1266-1269, & fins. 3, 4).
Though I would not do so for reasons discussed below, I therefore assume, as Justice Werdegar concludes, that we could now construe this “existing” state-privilege-related immunity to include protection against use for impeachment. (Cf. People v. Macias (1997) 16 Cal.4th 739, 751-753 [66 Cal.Rptr.2d 659, 941 P.2d 838] (Macias).) In that event, reversible prejudice would presumably be measured by the standard applicable to errors of state law. (See People v. Cahill (1993) 5 Cal.4th 478, 487-510 [20 Cal.Rptr.2d 582, 853 P.2d 1037]; People v. Watson (1956) 46 Cal.2d 818, 835 [299 P.2d 243].) *1257However, by rejecting this option, and placing its ruling squarely on federal constitutional grounds, the majority locks in the more stringent standard of reversibility set forth in Chapman v. California (1967) 386 U.S. 18 [17 L.Ed.2d 705, 87 S.Ct. 824], The majority’s constitutional ruling is unnecessary and incorrect.
Even where federal constitutional principles preclude substantive use of an accused’s statements to prove his criminal guilt, the United States Supreme Court has stressed that it has denied impeachment use of such statements in only one instance—where the statements were truly involuntary. (Michigan v. Harvey (1989) 494 U.S. 344, 351 [108 L.Ed.2d 293, 110 S.Ct. 1176] (Harvey), citing, as examples, New Jersey v. Portash (1979) 440 U.S. 450 [59 L.Ed.2d 501, 99 S.Ct. 1292] (Portash) [grand jury testimony under statutory grant of use immunity, but subject to threat of contempt for refusal to talk]; Mincey v. Arizona (1978) 437 U.S. 385 [57 L.Ed.2d 290, 98 S.Ct. 2408] [statements extracted over protests of seriously wounded suspect in hospital intensive care unit].)
If no true coercion or compulsion is involved, both the high court and the courts of this state have held that, even when an accused’s statements in a particular context are inadmissible to prove he committed a crime, they are available to impeach him if he voluntarily testifies at the trial on criminal charges or allegations. (E.g., Harvey, supra, 494 U.S. 344, 348-354 [voluntary statements elicited by police-initiated conversation with custodial defendant who had previously invoked Sixth Amendment right to counsel]; Oregon v. Hass (1975) 420 U.S. 714, 720-724 [43 L.Ed.2d 570, 95 S.Ct 1215] [voluntary statements obtained in violation of Miranda v. Arizona (1966) 384 U.S. 436 [16 L.Ed.2d 694, 86 S.Ct. 1602]]; Harris v. New York (1971) 401 U.S. 222, 224-226 [28 L.Ed.2d 1, 91 S.Ct. 643] (Harris) [same]; People v. Peevy (1998) 17 Cal.4th 1184,1191-1208 [73 Cal.Rptr.2d 865, 953 P.2d 1212] [voluntary statements elicited in deliberate violation of Miranda]; People v. Coleman (1975) 13 Cal.3d 867, 892 [120 Cal.Rptr. 384, 533 P.2d 1024] [inconsistent statements at probation revocation hearing]; People v. Crow (1994) 28 Cal.App.4th 440, 449-453 [33 Cal.Rptr.2d 624] [prior inconsistent statements during unsuccessful plea negotiations]; People v. Drews (1989) 208 Cal.App.3d 1317, 1324-1326 [256 Cal.Rptr. 846] [prior inconsistent statements during pretrial suppression hearing]; People v. Stanfill (1986) 184 Cal.App.3d 577, 581-582 [229 Cal.Rptr. 215] (Stanfill) [prior inconsistent statements to court-appointed competency examiners]; Sheila O. v. Superior Court (1981) 125 Cal.App.3d 812, 816-817 [178 Cal.Rptr. 418] [juvenile’s testimony at fitness hearing]; cf. United States v. Havens (1980) 446 U.S. 620, *1258624-628 [64 L.Ed.2d 559, 100 S.Ct. 1912] [physical evidence obtained in violation of Fourth Amendment]; but see Baqleh v. Superior Court (2002) 100 Cal.App.4th 478, 499, fn. 5 [122 Cal.Rptr.2d 673] (Baqleh) [statements to competency examiners not available for impeachment]; People v. Harris (1987) 192 Cal.App.3d 943, 949-950 [237 Cal.Rptr. 747] [same].)
Whether substantive use protection is granted to protect constitutional rights, or to encourage the accused to speak the truth in a particular nontrial setting, or both, modem California and high court cases have emphasized that these considerations do not give the accused a license to commit perjury on the witness stand. In this regard, the United States Supreme Court has noted that “[e]very criminal defendant is privileged to testify in his own defense, or to refuse to do so. But. . . [h]aving voluntarily taken the stand, [the accused is] under an obligation to [testify] truthfully and accurately,” and by impeaching him with his prior inconsistent statements, “the prosecution [does] no more than utilize the traditional truth-testing devices of the adversary process.” (Harris, supra, 401 U.S. 222, 225, italics added.)
In Macias, supra, 16 Cal.4th 739, we considered a question similar to that which confronts us here. Macias addressed California’s long-standing judicial use immunity for a juvenile’s statements to a probation officer evaluating whether the minor is fit for treatment within the juvenile system or instead must be tried as an adult (see Ramona R., supra, 37 Cal.3d 802). The issue was whether this immunity extended to use of such statements to impeach the minor’s testimony at his subsequent adult criminal trial. A majority of this court concluded that the answer is “no.”
Ramona R. had determined that although the minor was not statutorily compelled to speak to the probation officer, use immunity was essential to protect the juvenile’s California right not to incriminate herself. Otherwise, Ramona R. reasoned, the minor would be forced to choose between cooperating fully with the probation officer, thereby obtaining fair treatment at the fitness hearing, or remaining silent, thus preserving her privilege against self-incrimination. As Ramona R. observed, the juvenile’s lack of communication could be used against her in the fitness determination—especially when, as in the murder case there at issue, the burden of proving fitness for juvenile treatment was on her—and “the certification of a juvenile offender to an adult court has been accurately characterized as ‘the worst punishment the juvenile system is empowered to inflict.’ [Citation.]” (Ramona R., supra, 37 Cal.3d 803, 810.) “Hence, we concluded [in Ramona /?.] that the consequences of deciding between silence and incrimination are so severe that they warrant substantive use immunity for statements the minor makes in preparation for a fitness hearing. [Citation.]” (Macias, supra, 16 Cal.4th 739, 750.)
*1259As the plurality opinion in Macias explained, “[t]he purpose of the Ramona R. use immunity is to encourage the minor to give the probation officer candid and unencumbered evidence to aid the officer’s—and ultimately the court’s—determination of the best forum to consider the case. [Citation.] The grant of immunity also avoids the risk that the prosecution might take unfair advantage of an admission or silence by using it against the minor at a subsequent trial. [Citation.] In other words, substantive use immunity allows juveniles to exercise their right to present mitigating evidence to probation officers without giving prosecutors in subsequent trials the unfair advantage of using their statements as substantive evidence of guilt. [Citation.]” (Macias, supra, 16 Cal.4th 739, 752-753.)
However, the plurality opinion in Macias concluded, “we can easily distinguish the prosecution’s use for impeachment purposes of a juvenile’s statements made to a probation officer determining fitness from the use of those statements as substantive evidence of guilt. . . . [N]othing in the state Constitution or our judicial decisions protects juveniles from impeachment if their voluntary trial testimony is inconsistent with the substantively immunized statements they made to their probation officers before their fitness hearings.” (Macias, supra, 16 Cal.4th 739, 753, italics added.)
As part of its analysis, the plurality opinion in Macias traced the history of California’s pre-Proposition 8 rule which, contrary to United States Supreme Court decisions addressing the federal Constitution, had precluded even the impeachment use of statements obtained in violation of Miranda. (See People v. Disbrow (1976) 16 Cal.3d 101 [127 Cal.Rptr. 360, 545 P.2d 272]; cf. Harris, supra, 401 U.S. 222.) As the Macias plurality opinion explained, we concluded after Proposition 8 that the truth-in-evidence provisions of that initiative measure had abrogated the Disbrow ruling and required California’s adherence to Harris. (People v. May (1988) 44 Cal.3d 309 [243 Cal.Rptr. 369, 748 P.2d 307].) In this regard, the Macias plurality opinion stressed May's observation that “the ‘federal rule announced in Harris . . . , allowing impeachment by the defendant’s prior statements taken in violation of Miranda, may have been based on the premise that the privilege against self-incrimination cannot be invoked by one who has voluntarily taken the witness stand to testify concerning the subject matter of his prior statement. [Citations.]’ ” (Macias, supra, 16 Cal.4th 739, 752, quoting May, supra, 44 Cal.3d 309, 319, italics added; see also Stanfill, supra, 184 Cal.App.3d 577, 581-582.)
Macias also expressly distinguished and limited Portash, supra, 440 U.S. 450, which had held that “legislatively compelled” testimony at a grand jury proceeding, given pursuant to a statutory use immunity but under threat of contempt for any refusal to testify, could not be used against the witness for *1260any criminal purpose, including impeachment. As Macias explained, “[w]e agree . . . that 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 [voluntarily] made to a probation officer in preparation for a juvenile fitness hearing to impeach the same minor defendant’s voluntary, inconsistent trial statements, [f] The United States Supreme Court has recognized that Portash was a unique and limited case, demonstrating the essence of coerced testimony in the ‘classic Fifth Amendment’ sense because a witness who had been given use immunity was later ordered to testify or face contempt sanctions. [Citation.]” (Macias, supra, 16 Cal.4th 739, 754-755.)1
This case cannot be distinguished from Macias in any material way. In each instance, California has recognized a use immunity for statements made by a criminal accused in a particular proceeding—one not intended to obtain evidence of criminal guilt—in order to encourage the accused to speak, and to do so candidly and truthfully, for purposes of the proceeding at issue, without compromising the privilege against self-incrimination. Yet California law does not compel the accused to speak in either situation. Thus, protection of state and federal self-incrimination principles does not require that the prohibition on substantive use of the accused’s voluntary statements be extended to use for impeachment. Here, as in Macias, when the accused later voluntarily takes the stand and changes his story, the prosecution must be permitted to challenge his credibility by bringing to light his inconsistent prior statements.
In its attempt to distinguish Macias, the majority purports to apply a balance-of-interests test, concluding that the balance must be struck differently here than in Macias. The majority stresses the importance of the constitutional right not to be tried while incompetent, the concomitant need for reliability in the competency evaluation, and the resulting strength of the policy that the examinee not be discouraged by self-incrimination concerns *1261from responding to the examiners’ questions. The majority observes in particular that, unlike the juvenile fitness evaluation procedure at issue in Macias, which “provides . . . alternatives ... for producing any mitigating evidence that would rebut the fitness presumption” (Macias, supra, 16 Cal.4th 739, 752), a reliable competency evaluation requires a direct examination of the accused, in which candid and truthful answers to examiners’ questions are crucial.2 Finally, the majority notes that, in a juvenile fitness evaluation, the minor’s counsel may be present at any interview of the minor by the probation officer, while counsel may be excluded from a competency examination.
But nothing in these suggested distinctions demonstrates that we should interpret the Fifth Amendment to preclude use for impeachment of the accused’s voluntary statements to competency examiners. As noted above, time and again the United States Supreme Court has indicated that this most stringent use restriction is limited, for federal constitutional purposes, to statements that were truly involuntary when made. In all other situations, the high court has counseled, even if self-incrimination considerations prohibit the substantive criminal use of an accused’s statements, the statements are available to impeach the accused’s later testimony, because the voluntary decision to take the stand at trial includes the obligation to testify truthfully, and the Fifth Amendment is not a license to commit perjury.3
Contrary to the majority’s implication, nothing in Estelle v. Smith (1981) 451 U.S. 454 [68 L.Ed.2d 359, 101 S.Ct. 1866] (Estelle) compels the majority’s result. If anything, Estelle supports the conclusion that, for purposes of the federal Constitution, an accused’s uncompelled statements to competency examiners are available for impeachment. The core holding of Estelle—which did not directly involve the impeachment issue—is that “[a] criminal defendant, who neither initiates a psychiatric evaluation nor attempts *1262to introduce any psychiatric evidence, may not be compelled to respond to a psychiatrist if his statements can be used against him” on the issues of guilt or penalty. (Estelle, supra, at p. 468, italics added; see also id. at pp. 462-463.) Thus “[i]f, upon being adequately warned [that he has the right to remain silent, and that he may incriminate himself by speaking], [the defendant] . . . indicate^] that he [will] not answer [the examiner’s] questions, [a] validly ordered competency examination nevertheless [may] proceed[] upon the condition that the results [will] be applied solely for that purpose.” (Id. at p. 468.)
Much of Estelle's analysis focused on the need to withhold incriminatory use of statements made by the defendant during a compulsory court-ordered competency examination where the defendant was not fully advised of his Fifth Amendment rights and given an opportunity to invoke or waive them. In this regard, Estelle drew a direct analogy to Miranda.
As Estelle indicated, the considerations leading to Miranda's requirement that a suspect undergoing interrogation in the inherently coercive atmosphere of police custody receive such warnings “apply with no less force to the pretrial psychiatric examination at issue here.” (Estelle, supra, 451 U.S. 454, 467.) The accused in Estelle was in custody, the court’s opinion explained, and, even though the psychiatrist was court-appointed and ostensibly neutral, when he testified against Estelle at the latter’s penalty trial, “his role changed and became essentially like that of an agent of the State recounting unwarned statements made in a postarrest custodial setting. During the psychiatric evaluation, [the defendant] assuredly was ‘faced with a phase of the adversary system’ and was ‘not in the presence of [a] perso[n] acting solely in his interest.’ [Citation.] Yet he was given no indication that the compulsory examination would be used to gather evidence necessary to decide whether, if convicted, he should be sentenced to death. He was not informed that, accordingly, he had a constitutional right not to answer the questions put to him.” (Ibid.)
Though “ ‘[volunteered statements ... are not barred by the Fifth Amendment,’ ” the court concluded, “under Miranda ... we must conclude that, when faced while in custody with a court-ordered psychiatric inquiry, [the defendant’s] statements to [the examiner] were not ‘given freely and voluntarily without any compelling influences’ and, as such, could be used as the State did at the penalty phase only if [the defendant] had been apprised of his rights and had knowingly decided to waive them. [Citation.]” (Estelle, supra, 451 U.S. 454, 469.)
*1263Thus, Estelle likened a custodial accused’s court-ordered competency examination to a custodial police interrogation, in which, even if strict coercion is not present, the situation has an inherently coercive atmosphere which must be ameliorated by advisements of Fifth Amendment rights and an opportunity to invoke them. Of course, statements obtained, without proper advisements, in the coercive environment of custody may not be used as substantive proof of the accused’s guilt, but they may be used for impeachment unless they were truly involuntary,4
I realize that under California’s judicially declared use immunity, the defendant need not be warned he has a Fifth Amendment right not to speak to competency examiners. Indeed, California decisions have suggested that the accused cannot invoke his Fifth Amendment privilege as a means of avoiding compelled submission to a court-ordered competency examination, because the use immunity itself affords all protection the Constitution would provide against the criminal use of his statements to the examiners. (See People v. Weaver (2001) 26 Cal.4th 876, 959, 961 [111 Cal.Rptr.2d 2, 29 P.3d 103]; Arcega, supra, 32 Cal.3d 504, 523, fn. 6; Tarantino, supra, 48 Cal.App.3d 465, 470.)
But a use immunity arising under state law, even if adopted to protect the right against self-incrimination, cannot expand the scope of the federal Constitution—the basis on which the majority purports to decide this case. As the majority itself makes clear, even if a defendant must face court-appointed competency examiners, nothing in California law compels him to speak to them, though, in consequence of the use immunity, he cannot invoke federal or state constitutional privileges against self-incrimination as a basis for declining to do so. If he chooses to speak under such circumstances, it appears the self-incrimination provisions of the federal Constitution do not preclude impeachment use of his voluntary statements.
*1264The majority worries that if a defendant’s statements during a court-ordered competency examination can be used to impeach his later, inconsistent trial testimony, his counsel will warn him not to cooperate, and the purpose of the examination will be thwarted. Of course, to the extent a similar consideration was present in Macias, it did not dissuade us from concluding that the statements at issue there could be used for impeachment.
In any event, as competent counsel should understand, it remains in the defendant’s interest to cooperate fully in a court-ordered competency examination, in order to minimize the chance of an erroneous determination on the issue of competence to stand trial. In return for this cooperation, counsel may advise, the defendant receives full substantive immunity from criminal use of his statements—the prosecution cannot obtain an unfair advantage by employing the statements as affirmative proof of his guilt.
If the defendant’s statements may be used for impeachment, he suffers that consequence only if he voluntarily testifies in his own behalf at trial, and, in doing so, makes statements at odds with what he told the competency examiners—an indication that he has lied in one instance or the other. A rule forbidding impeachment, on the other hand, gives the defendant an unfair advantage—he may testify falsely, secure in the knowledge that the fact finder will not learn of contrary statements he has made in the past. In my view, it does not thwart the legitimate purposes of a competency examination for counsel to advise his client that, while his statements cannot be used to prove his guilt, they may come back to haunt him if he testifies at trial and changes his story. In effect, such advice promotes the proper purposes of both the competency examination and the trial—to discover the truth.
Finally, the majority suggests that, under the Sixth Amendment, allowing use of a competency examinee’s statements for impeachment might compromise the current California practice which allows the defendant’s counsel to be excluded from the examination itself. I am not persuaded. In the first place, as the majority acknowledges, federal decisions are split about whether voluntary statements obtained in direct violation of the Sixth Amendment may be used for impeachment. More fundamentally, I seriously question whether the Sixth Amendment right to counsel includes the unqualified right to the personal presence of counsel at a proceeding, such as a competency examination, that is not concerned with obtaining evidence of the defendant’s guilt.
Decades ago this court held that, where the defendant’s Sixth Amendment right to counsel had attached, and the defendant was represented by counsel, statements obtained at a psychiatric examination in counsel’s unwaived absence could be admitted at the guilt trial only if counsel was notified of the *1265examination in advance, the defendant placed his mental condition in issue at trial, and the statements were used solely to support the psychiatrist’s expert opinion. (In re Spencer (1965) 63 Cal.2d 400, 409-412 [46 Cal.Rptr. 753, 406 P.2d 33]; see also In re Cowans (1970) 2 Cal.3d 733, 737-738 [87 Cal.Rptr. 499, 470 P.2d 635]; People v. Morse (1969) 70 Cal.2d 711, 738 [76 Cal.Rptr. 391, 452 P.2d 607].) But none of our decisions on this subject involved the use of such statements exclusively to impeach the defendant’s own trial testimony.
Moreover, the high court’s more recent decision in Estelle strongly suggested that, while the defendant has a Sixth Amendment right to his counsel’s help and guidance in connection with a court-ordered psychiatric examination, he is not entitled to counsel’s personal presence at the examination itself. In Estelle, after Benjamin Ernest Smith was indicted for murder, and while he was confined in jail, he was examined for trial competency by a court-appointed psychiatrist. Smith’s appointed counsel were not present at the examination; indeed, it was not clear counsel had received notice of the psychiatrist’s appointment, and counsel were not advised until afterward that the examination had occurred. (Estelle, supra, 451 U.S. 454, 457-459 & fn. 5, 471, fn. 15.) Later, at Smith’s sentencing trial, the psychiatrist testified that Smith would commit violent criminal acts in the future if given the opportunity to do so.
In its Sixth Amendment discussion, Estelle held that Smith’s right to counsel had been violated insofar as “[d]efense counsel. . . were not notified in advance that the psychiatric examination would encompass the issue of their client’s future dangerousness, and [Smith] was denied the assistance of his attorneys in making 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. 454, 470-471, fn. omitted, italics added.)
The court pointed out that “[b]ecause ‘[a] layman may not be aware of the precise scope, the nuances, and the boundaries of Ms Fifth Amendment privilege,’ the assertion of that right ‘often depends upon legal advice from someone who is trained and skilled in the subject matter.’ [Citation.]” Given the difficult choices to be made in deciding whether to undergo an examination, and how to approach it, said the court, “[i]t follows logically . . . that a defendant should not be forced to resolve such an important issue without ‘the guiding hand of counsel.’ [Citation.]” (Estelle, supra, 451 U.S. 454, 471.)
Though counsel were given no opportunity to attend the examination in Estelle, the Mgh court expressly declined to identify counsel’s absence as a violation of Smith’s Sixth Amendment rights. Estelle merely indicated that *1266Smith’s right to the “assistance” of counsel (Estelle, supra, 451 U.S. 454, 471) was infringed when he was denied an advance opportunity to consult with his attorneys.
Indeed, in a telling footnote, the. Estelle court remarked: “[Smith] does not assert, and the Court of Appeals did not find, any constitutional right to have counsel actually present during the examination. In fact, the Court of Appeals recognized that ‘an attorney present during the psychiatric interview could contribute little and might seriously disrupt the examination.’ [Citations.]” (Estelle, supra, 451 U.S. 454, 470, fri. 14.)
Given this strong signal from the high court, and notwithstanding our older precedents, I am not willing to assume that the Sixth Amendment requires counsel’s presence at a California competency examination before the examinee’s statements may be used to impeach him when, after consulting with counsel, he later voluntarily takes the stand and testifies in a manner inconsistent with his statements to the examiners.
For all these reasons, I respectfully dissent from the majority’s conclusions that the federal Constitution, or any other principle of law, barred impeachment use of defendant’s voluntary statements to his court-appointed competency examiners.
Corrigan, J., concurred.
As Macias observed, the high court had declined to apply Portash in two later decisions, South Dakota v. Neville (1983) 459 U.S. 553 [74 L.Ed.2d 748, 103 S.Ct. 916], and Minnesota v. Murphy (1984) 465 U.S. 420 [79 L.Ed.2d 409, 104 S.Ct. 1136]. In Neville, the court held that the defendant’s decision whether to submit to a blood-alcohol test was not “legislatively compelled” in the Portash sense unless he 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. (Neville, supra, at p. 562.) In Murphy, a probationer was under a court order to meet with his probation officer and respond truthfully to the officer’s questions. Nonetheless, the United States Supreme Court held that statements he volunteered to the officer were not “compelled,” and were thus admissible in his criminal trial, even though the officer did not advise him of his privilege against self-incrimination and threatened to revoke probation if he lied. (Murphy, supra, at p. 440.)
Although Macias took passing note that the minor facing a fitness evaluation has alternative means of presenting mitigating evidence, the fact remains that the use immunity there at issue, like the one here, is heavily premised on encouraging the subject to speak, and to do so candidly and truthfully. In Ramona R., supra, 37 Cal.3d 802, which confirmed that the juvenile fitness use immunity survived Proposition 8, this court explained the policy behind that immunity by quoting heavily from In re Wayne H. (1979) 24 Cal.3d 595 [156 Cal.Rptr. 344, 596 P.2d 1], which similarly immunized a juvenile’s statements to a probation officer for purposes of determining the proper disposition if guilt is established. As was noted, “ ‘[s]uch [dispositional] decisions, courts have uniformly concluded, should be based on the most complete knowledge of the defendant’s background that is possible. His description and explanation of the circumstances of the alleged offense, and his acknowledgment of guilt and demonstration of remorse, may significantly affect decisions about punishment or transfer for adult proceedings.’ ” (Ramona R., supra, at p. 806, quoting Wayne H., supra, at pp. 599-600.)
I discuss below the Sixth Amendment implications of counsel’s exclusion from a competency examination.
Estelle involved a competency examination conducted under Texas law. In federal criminal trials, use of an accused’s statements in a court-ordered competency examination is presently governed by rule 12.2(c)(4) of the Federal Rules of Criminal Procedure (18 U.S.C.). This rule provides that “[a] statement made by a defendant in the course of any [such] examination . . . may be [introduced] against the defendant in any criminal proceeding” only as it bears on a mental condition the defendant himself has placed in issue. My research discloses only one case interpreting this language (formerly contained in 18 U.S.C. § 4244) on the narrow issue whether such statements may be used to impeach the defendant’s inconsistent trial testimony. That decision, one which predated Estelle, upheld such use, though noting that the psychiatrist’s challenged testimony had merely rebutted the defendant’s testimonial claim that he did not recall the circumstances of the offense. (United States v. Castenada (7th Cir. 1977) 555 F.2d 605, 609-610.)