Opinion
LUCAS, C. J. Introduction
The issues addressed by the Court of Appeal in this case were (1) whether the results of a horizontal gaze nystagmus (HGN) field sobriety test are admissible in the absence of a Kelly/Frye foundational showing, that is, foundational evidence disclosing general acceptance of the test within the relevant scientific community (see People v. Kelly (1976) 17 Cal.3d 24 [130 Cal.Rptr. 144, 549 P.2d 1240] [hereafter Kelly]; Frye v. United States (D.C. Cir. 1923) 293 F. 1013, 1014 [54 App.D.C. 46, 34 A.L.R. 145] (hereafter Frye)), and (2) whether a police officer without scientific expertise is qualified to give an opinion concerning the results of the HGN test. The Court of Appeal answered both questions in the negative and reversed defendant Leahy’s convictions for driving under the influence of alcohol (Veh. Code, § 23152, subd. (a)) and driving with a blood-alcohol level in excess of .08 percent (id., subd. (b)).
We granted review and asked for supplemental briefing on the question whether the Kelly/Frye standard for admitting the results of new scientific techniques should be modified following the United States Supreme Court’s decision in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) 509 U.S. _[125 L.Ed.2d 469,113 S.Ct. 2786] (hereafter Daubert)], holding that Frye was abrogated by rule 702 of the Federal Rules of Evidence (28 U.S.C.). As will appear, after reviewing such additional briefing and argument, we conclude that the Kelly/Frye formulation (or now more accurately, the Kelly formulation) should remain a prerequisite to the admission of expert testimony regarding new scientific methodology in this state. We further [592]conclude, consistent with the Court of Appeal’s conclusions herein, that the HGN test is a “new scientific technique” within the scope of Kelly, and that the trial court improperly admitted police testimony regarding that technique without first requiring compliance with Kelly.
Accordingly, we affirm the judgment of the Court of Appeal reversing defendant Leahy’s conviction on the ground of failure to comply with Kelly, and direct a remand to the trial court for a Kelly hearing in accordance with our opinion.
Facts
The following facts were taken largely from the Court of Appeal opinion. Although that court also resolved a consolidated appeal in an unrelated case (People v. Tatar), we confine our discussion to the appeal of defendant William Michael Leahy.
Leahy was stopped after a police officer observed him driving a car traveling 55 miles per hour in a 25-mile-per-hour zone. Leahy’s face was flushed, his eyes were red and watery, his speech was slurred, his balance was unsteady, and he exuded the odor of alcohol. Despite these relatively conventional indicia of intoxication, the officer was not convinced defendant was under the influence of alcohol. The officer decided to give defendant some field sobriety tests.
Defendant passed two such tests, the “internal clock” test and the “alphabet” test. He was also required, however, to take the HGN test. As a recent appellate decision explains, “Nystagmus is an involuntary rapid movement of the eyeball, which may be horizontal, vertical, or rotary. [Citation.] An inability of the eyes to maintain visual fixation as they are turned from side to side (in other words, jerking or bouncing) is known as horizontal gaze nystagmus, or HGN. [Citation.] Some investigators believe alcohol intoxication increases the frequency and amplitude of HGN and causes HGN to occur at a smaller angle of deviation from the forward direction. [Citation.]” (People v. Ojeda (1990) 225 Cal.App.3d 404, 406 [275 Cal.Rptr. 472].)
In the present case, the officer believed that defendant failed the HGN test, and accordingly he arrested defendant. A subsequent intoxilyzer breath test revealed a .10 percent blood-alcohol level. Accordingly, defendant was charged with driving under the influence of alcohol (Veh. Code, § 23152, subd. (a)) and driving with a blood-alcohol level in excess of .08 percent (id., § 23152, subd. (b)). Defendant made a motion in limine to bar evidence of the HGN test result based on Kelly, supra, 17 Cal.3d 24, and Frye, supra, 293 F. 1013. The trial court denied the motion.
[593]The trial court determined that “the Kelly-Frye rule is inapplicable because the nature of this test isn’t a specific test for the determination of alcohol; it is only a symptom that the officer is testifying to . . .in the same manner as he might be testifying to a symptom of slurred speech or a person’s face turning red, or . . . bloodshot eyes. It would be on that type of reasoning that it would be allowed in.” Thus, the arresting officers were permitted to testify, over continuing objection, concerning the relationship between the HGN test and defendant’s intoxication.
Court of Appeal Decision
The Court of Appeal focused primarily on the question whether police officers were competent to testify regarding HGN test results in light of the Kelly/Frye rule. The court assumed the continued vitality of the Kelly! Frye formulation, and concluded that the HGN test was indeed a scientific technique requiring expert foundational testimony. (Compare People v. Ojeda, supra, 225 Cal.App.3d at pp. 407-409 [allowing police officer to testify regarding HGN test results as indicating defendant’s intoxication], with People v. Williams (1992) 3 Cal.App.4th 1326, 1332-1335 [5 Cal.Rptr.2d 130] [disallowing officer’s opinion testimony, based on HGN test, that suspect had consumed alcohol], and People v. Loomis (1984) 156 Cal.App.3d Supp. 1, 5-7 [203 Cal.Rptr. 767] [disallowing police officer’s opinion testimony, based on HGN test results, regarding suspect’s blood-alcohol level].)
The Court of Appeal agreed with the analyses of the Williams and Loomis courts and concluded “[i]t was error to admit HGN evidence as either lay or expert testimony without a proper scientific foundation. The usual field sobriety tests are grounded in common knowledge, i.e., that intoxicated persons will often demonstrate lack of concentration, judgment, balance, and coordination. HGN is not. [f| Consequently, at least as the law of California currently stands, it will be error in the event of any retrial to permit such evidence as the basis of an opinion concerning intoxication without a Kelly-Frye foundation, i.e., proof of general acceptance of HGN in the scientific community. [Footnote omitted.]”
Discussion
We will first discuss the background leading to adoption of the Kelly/Frye formulation and then outline some of the considerations which militate for or against its retention. We next will address the Daubert decision and its effect on that formulation. As will appear, we conclude, consistent with the views of both parties herein, that Daubert affords no [594]compelling reason for abandoning Kelly in favor of the more “flexible” approach outlined in Daubert. Then we will turn to the question whether the trial court erred in permitting the officer to testify regarding the results of the HGN test given to defendant, and whether that error requires reversal of the judgment against defendant.
1. People v. Kelly—Our unanimous 1976 Kelly decision (17 Cal.3d 24) involved the admissibility of voiceprint evidence produced by a technique used to identify voices by spectrographic analysis. That case first set forth certain “general principles of admissibility” of expert testimony based on new scientific techniques, including the following “traditional” two-step process: “(1) [T]he reliability of the method must be established, usually by expert testimony, and (2) the witness furnishing such testimony must be properly qualified as an expert to give an opinion on the subject. (See Evid. Code, §§ 720, 801 . . . .) Additionally, the proponent of the evidence must demonstrate that correct scientific procedures were used in the particular case. [Citations.]” (Kelly, supra, 17 Cal.3d at p. 30, italics in original; see also People v. Diaz (1992) 3 Cal.4th 495, 526 [11 Cal.Rptr.2d 353, 834 P.2d 1171], and cases cited.)
Kelly next considered the appropriate test for determining the reliability of a new scientific technique. We recognized that one possible approach would be to leave questions of admissibility to the discretion of the trial court in the first instance, “in which event objections, if any, to the reliability of the evidence (or of the underlying scientific technique on which it is based) might lessen the weight of the evidence but would not necessarily prevent its admissibility.” (17 Cal.3d at p. 31.)
We rejected the foregoing approach, however, and confirmed allegiance to the “germinal” Frye decision, supra, 293 F. 1013, and its formulation, as follows: “Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.” (Id. at p. 1014, italics added and quoted in Kelly, supra, 17 Cal.3d at p. 30.)
In Kelly, we explained that prior California cases, and “most” sister state cases, have followed Frye and “assigned the task of determining reliability of the evolving technique to members of the scientific community from which the new method emerges.” (Kelly, supra, 17 Cal.3d at p. 31.) We [595]observed that the Frye standard holds several advantages, including (1) assuring that those persons most qualified to assess the validity of a scientific technique would have the determinative voice, (2) providing a “minimal reserve of experts” to critically examine each technique in a particular case, (3) promoting uniformity of decision based on finding a consensus in the scientific community, and (4) protecting the parties by its “essentially conservative nature.” (Ibid.)
Expounding on the last factor, we noted that “[s]everal reasons . . . support a posture of judicial caution in this area. Lay jurors tend to give considerable weight to ‘scientific’ evidence when presented by ‘experts’ with impressive credentials. We have acknowledged the existence of a ‘. . . misleading aura of certainty which often envelops a new scientific process, obscuring its currently experimental nature.’ [Citation.]” (17 Cal.3d at pp. 31-32.) We further noted that once a trial court has admitted evidence derived from a new technique and the decision is affirmed on appeal in a published opinion, it will become precedent controlling subsequent trials. (Id. at p. 32.) Thus, it is essential that the decision to admit such evidence is carefully considered.
For all the foregoing reasons, in Kelly we deemed the more cautious Frye formulation preferable to simply submitting the matter to the trial court’s discretion for decision in each case. We now review that conclusion in light of a recent decision by the United States Supreme Court.
2. Daubert v. Merrell Dow Pharmaceuticals, Inc.—In Daubert, supra, 509 U.S._[125 L.Ed.2d 469], plaintiffs sued the manufacturer (Merrell Dow) of the anti-nausea drug Bendectin, alleging its ingestion caused birth defects. Merrell Dow moved for summary judgment, submitting an affidavit from an expert epidemiologist, Dr. Lamm, who stated that none of the 30 pertinent published studies had ever found Bendectin capable of causing malformations in fetuses. Rather than directly contest Dr. Lamm’s factual statements, plaintiffs responded with their own experts’ declarations to the effect that their unpublished studies, and reanalyses of published studies, indicated a link between Bendectin and fetal malformation.
The federal district court granted Merrell Dow’s motion for summary judgment on the basis that the scientific theories of plaintiffs’ experts failed to meet Frye's “general acceptance” standard. (See Daubert v. Merrell Dow Pharmaceuticals, Inc. (S.D.Cal. 1989) 727 F.Supp. 570, 572-576.) The United States Court of Appeals for the Ninth Circuit affirmed. (See Daubert v. Merrell Dow Pharmaceuticals, Inc. (9th Cir. 1991) 951 F.2d 1128.) That court ruled that expert opinion based on methodology diverging “significantly from the procedures accepted by recognized authorities in the field . . . [596]cannot be shown to be ‘generally accepted as a reliable technique,’. . {Id. at p. 1130.) The Court of Appeals rejected plaintiffs’ reanalyses as “unpublished, not subjected to the normal peer review process and generated solely for use in litigation.” {Id. at p. 1131, fn. omitted.) The high court granted certiorari in light of “sharp divisions among the courts regarding the proper standard for the admission of expert testimony.” (See Daubert, supra, 509 U.S. at p. _ [125 L.Ed.2d at pp. 477-478].)
The Supreme Court observed that although the Frye standard has been the “dominant” one in the 70 years since its formulation, it has come under “increasing attack of late.” (509 U.S. at p._, and fn. 4 [125 L.Ed.2d at p. 478].) Indeed, according to the high court, “The merits of the Frye test have been much debated, and scholarship on its proper scope and application is legion.” {Id. at p. _, fn. omitted [125 L.Ed.2d at p. 478].) The court, however, found it unnecessary to resolve the debate. Instead, the court concluded that the Frye test had been superseded by adoption of the Federal Rules of Evidence in 1975. (See 28 U.S.C.A.)
Rule 402 of the Federal Rules of Evidence provides that “All relevant evidence is admissible, except as otherwise provided [by law]. Evidence which is not relevant is not admissible.” Rule 401 defines “relevant evidence” as evidence having “any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.” As the high court notes, the rule’s standard of relevance “thus is a liberal one.” (509 U.S. at p. _ [125 L.Ed.2d at p. 479].)
Additionally, the Supreme Court in Daubert relied on rule 702 of the Federal Rules of Evidence, governing expert testimony: “If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.” As the court explained, “[n]othing in the text of this Rule [rule 702] establishes ‘general acceptance’ as an absolute prerequisite to admissibility. Nor does [Merrell Dow] present any clear indication that Rule 702 or the Rules as a whole were intended to incorporate a ‘general acceptance’ standard. The drafting history makes no mention of Frye, and a rigid ‘general acceptance’ requirement would be at odds with the ‘liberal thrust’ of the Federal Rules and their ‘general approach of relaxing the traditional barriers to “opinion” testimony.’ [Citations.] . . . Given the Rules’ permissive backdrop and their inclusion of a specific rule on expert testimony that does not mention ‘general acceptance,’ the assertion that the Rules somehow assimilated Frye is unconvincing.” (509 U.S. at p. _ [125 L.Ed.2d at p. 480].)
[597]The high court in Daubert concluded that Frye's “austere standard” was “absent from and incompatible with the Federal Rules of Evidence, [and] should not be applied in federal trials.” (509 U.S. at p--[125 L.Ed.2d at p. 480], fn. omitted.) In the following portion of its opinion, the court expounded on the screening functions federal courts should perform under rule 702 to assure that “any and all scientific testimony or evidence admitted is not only relevant, but reliable.” (509 U.S. at p--[125 L.Ed.2d at p. 480].); see also id., at pp__-_[see also id., at pp. 480-485].) We now turn to an analysis of the California statutory provisions governing the admissibility of expert evidence and address the question whether Daubert's holding provides an appropriate analogy supporting the abrogation of the Kelly formulation in this state.
3. California Provisions on Admissibility—Daubert, dealing with federal law, offers at most only persuasive authority to assist us in determining whether to reconsider our Kelly decision. We first review the California statutory provisions to determine whether the Kelly standard is “absent from and incompatible with” (see Daubert, supra, 509 U.S. at p--[125 L.Ed.2d at p. 480]) the California Evidence Code provisions regarding the admissibility of expert testimony.
The California Evidence Code was enacted in 1965, and the pertinent provisions have not been amended since that time. Section 350 (further statutory references are to the Evidence Code unless otherwise indicated) provides that “[n]o evidence is admissible except relevant evidence,” and section 351 provides that “[e]xcept as otherwise provided by statute, all relevant evidence is admissible.”
Section 210 defines “relevant evidence” as “evidence, including evidence relevant to the credibility of a witness or hearsay declarant, having any tendency in reason to prove or disprove any disputed fact that is of consequence to the determination of the action.” The foregoing provisions seem substantially equivalent to the “liberal” admissibility provisions of federal law (see Fed. Rules Evid., rules 401 and 402, 28 U.S.C.) cited in Daubert.
Sections 720 and 801 are the California provisions regarding admissibility of expert testimony. Section 720, subdivision (a), provides that “A person is qualified to testify as an expert if he has special knowledge, skill, experience, training, or education sufficient to qualify him as an expert on the subject to which his testimony relates. . . .” Subdivision (b) of that section provides that “[a] witness’ special knowledge . . . may be shown by any otherwise admissible evidence, including his own testimony.”
Section 801 permits an expert to state an opinion that is “(a) Related to a subject that is sufficiently beyond common experience that the opinion of an [598]expert would assist the trier of fact; and [^Q (b) Based on matter (including his special knowledge . . .) perceived by or personally known to the witness . . . , whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates, unless an expert is precluded by law from using such matter as a basis for his opinion.” (Italics added.)
In 1982, as a result of the passage of an anticrime initiative measure (Prop. 8), the voters adopted a constitutional “Truth-in-Evidence” provision (Cal. Const, art. I, § 28, subd. (d)), stating that “relevant evidence shall not be excluded in any criminal proceeding . . . .” In People v. Harris (1989) 47 Cal.3d 1047, 1093-1095 [255 Cal.Rptr. 352, 767 P.2d 619], we upheld a trial court ruling excluding polygraph evidence proffered by the defense. In doing so, we rejected the argument that adoption of the foregoing constitutional provision eliminated restrictions on polygraph test results. Thus, we stated that “[a]doption of section 28(d) did not, however, abrogate generally accepted rules by which the reliability and thus the relevance of scientific evidence is determined. (See People v. Kelly[, supra,] 17 Cal.3d 24 . . . .) The reliability of a scientific technique, therefore, is determined under the requirement of Evidence Code section 350, that ‘[n]o evidence is admissible except relevant evidence,’ a provision necessarily incorporated by reference into Evidence Code section 352, which is expressly preserved by section 28(d). [H . . . . [H . . . The applicable rule in this state, one unaffected by . . . the adoption of section 28(d), is that the admissibility of evidence based on a new scientific technique is determined under the principles of Frye v. United States[, supra,] 293 Fed. 1013,1014. . . .” (People v. Harris, supra, 47 Cal.3d at p. 1094.)
4. Survival of Kelly—Sections 720 and 801, in combination, seem the functional equivalent of Federal Rules of Evidence, rule 702, as discussed in Daubert. Although some language in section 801 is broad enough to include a Frye standard of general acceptance (matter “of a type that reasonably may be relied upon by an expert”), nothing in these sections expressly establishes general acceptance as an absolute prerequisite to admissibility, and nothing in the legislative history leading to adoption of the Evidence Code indicates that a general acceptance standard was intended. To paraphrase Daubert, the drafting history makes no mention of Frye, and a rigid general acceptance requirement might seem at odds with the liberal thrust of the Evidence Code and its general approach of relaxing the traditional barriers to “opinion” testimony.
Thus, were we approaching the question afresh, without the benefit of our analysis and holding in Kelly, supra, 17 Cal.3d 24, we might reasonably conclude, by analogy to Daubert, that the framers of the Evidence Code [599]did not intend to adopt a general acceptance standard. But Kelly was decided in 1976, 11 years after the adoption of the Evidence Code and its provisions governing the admissibility of expert testimony. (See Fishback v. People (Colo. 1993) 851 P.2d 884, 890 [retaining Frye on similar analysis].) We were presumably well aware in Kelly that the Frye “general acceptance” standard arguably was “absent from and incompatible with” the preexisting California statutory provisions. Nonetheless, we concluded otherwise and found Frye compatible with those provisions, which we cited in our opinion. (See Kelly, supra, 17 Cal.3d at p. 30.) No significant relevant developments have occurred in this state since Kelly was decided to justify abandoning its conclusions. Thus, the principle of stare decisis appears applicable here, unless the criticism of the Frye doctrine cited in Daubert and in other sources persuades us otherwise.
Both defendant and the People herein urge us to retain our Kelly holding. Defendant encourages us to preserve the “cautious” and “conservative” approach we deliberately chose in Kelly. The People (represented by the Orange County District Attorney) agree, stating, “there must be some standard test for the trial courts to follow to minimize the influx of what has come to be known as ‘junk science’ into the courtrooms of this state. The Kelly/Frye test, while not perfect, has acted to keep such unreliable evidence from the jury.” Amici curiae Los Angeles District Attorney (LADA), Criminal Justice Legal Foundation (CJLF), California Public Defenders’ Association, and Product Liability Advisory Counsel have also submitted briefs supporting the retention of Kelly.
LADA takes the position that for us to adopt Daubert would “ignore over forty years of precedent based upon policy considerations which have not changed, and without any compulsion to do so from the California Legislature or from the voters.” In the view of CJLF, “California should retain the Kelly rule as an important safeguard against untested and unproven scientific theories.” The other two above mentioned amici curiae are in general agreement.
The foregoing position, however, is not unanimous. Other amici curiae (namely, the State Attorney General and the Appellate Committee of the California District Attorneys Association (ACCDA)) urge us to employ the Daubert analogy and either discard, or substantially alter, our Kelly holding. It seems apparent from their briefs, however, that the primary concern of these amici curiae involves the interpretation and application of Kelly in the context of the deoxyribonucleic acid (DNA) cases (see, e.g., People v. Barney (1992) 8 Cal.App.4th 798 [10 Cal.Rptr.2d 731]). These amici seem more concerned with the narrow issue of the exclusion of DNA test evidence, an issue not involved here, than with the general question of the retention of Kelly.
[600]Amicus curiae ACCDA asserts that Kelly is unclear as to the proper standard for proving general acceptance by the scientific community. (Compare People v. Shirley (1982) 31 Cal.3d 18, 56 [181 Cal.Rptr. 243, 723 P.2d 1354] [opposition by scientists “significant either in number or expertise”] with People v. Guerra (1984) 37 Cal.3d 385, 418 [208 Cal.Rptr. 162, 690 P.2d 635] [unanimity of opinion unnecessary if use of technique supported by “clear majority” of the scientific community].) Because this issue may arise on remand, we address it briefly in this opinion (see post, at pp. 611-612).
Additionally, ACCDA suggests it is unclear how to apply Kelly’s requirement (see 17 Cal.3d at p. 30) that correct scientific procedures be employed in the case. (Compare People v. Farmer (1989) 47 Cal.3d 888, 913 [254 Cal.Rptr. 508, 765 P.2d 940] [careless testing affects weight of evidence not admissibility], with People v. Barney, supra, 8 Cal.App.4th at pp. 823-824 [Kelly’s “ ‘correct scientific procedures’ ” requirement “is not merely a question of weight but is an element of the Kelly-Frye admissibility determination”].) ACCDA urges us to modify our Kelly rule to clarify the foregoing uncertainties.
Amicus curiae Attorney General echoes the concerns of ACCDA, and asserts that Kelly/Frye (1) emphasizes “nose counting” of the scientific community rather than focusing directly on the reliability of the challenged technique, thereby excluding “demonstrably reliable, highly probative evidence, as it has in the case of DNA evidence,” (2) is premised on an unrealistic model of a “relatively monolithic scientific community,” (3) improperly defers to scientists the legal question of the admissibility of evidence; and (4) unduly penalizes crime victims, their families and friends by excluding relevant evidence of guilt.
The Attorney General also observes that the Kelly/Frye test is uncertain in various respects, such as (1) whether, and to what extent, it applies to expert testimony (see People v. McDonald (1984) 37 Cal.3d 351, 372-373 [208 Cal.Rptr. 236, 690 P.2d 709, 46 A.L.R.4th1011]), (2) whether there must be general acceptance of the scientific technique itself or merely the scientific principle underlying it, (3) whether “probability estimates” (e.g., in DNA cases) are subject to Kelly/Frye, (4) what is the “relevant” scientific community, and (5) what constitutes “general acceptance” (e.g., a simple majority, a consensus, or a significant minority).
The Attorney General further suggests that the supposed benefits of Kelly/Frye (e.g., minimizing undue influence on juries, leaving scientific questions to qualified scientists, avoiding multiple suits, and promoting [601]uniformity of decision) can be alternatively achieved by giving the trial courts broad discretion to decide admissibility questions, subject to vigorous cross-examination of experts, full presentation of contrary evidence, and careful jury instructions on the burden of proof. According to the Attorney General, the DNA cases demonstrate that KellylFrye does not guarantee against multiple litigation or conflicting decisions.
As with amicus curiae ACCDA, the Attorney General urges us to clarify or “fix” our Kelly rule in the following respects, should we elect not to abandon it entirely:
First, we should make clear that “general acceptance” does not require unanimity, a consensus of opinion, or even majority support by the scientific community. The Attorney General argues that general acceptance should mean that the technique “is accepted by other well credentialed scientists outside the testing laboratory . . . .” (Italics in original.)
Second, according to the Attorney General, we should clarify that Kelly does not apply to “probability estimates” such as those given in DNA cases, and we should hold that Kelly is inapplicable to the “particular standardized protocol" used to perform the test in the case at hand, rather than to the “fundamental validity” of the technique itself.
Finally, the Attorney General suggests we should adopt an abuse of discretion standard of appellate review, rather than permit a de novo review at the appellate level. (See People v. Barney, supra, 8 Cal.App.3d at pp. 810-811 [general acceptance of DNA testing subject to “limited de novo review” on appeal].)
In sum, rather than raise fundamental defects in our approach in Kelly, these amici curiae appear more concerned with clarifying or modifying our Kelly standard for use in future cases. But most of the suggested modifications or clarifications do not relate to issues presented in this case, and do not directly affect our decision whether or not to retain Kelly. Accordingly, we decline to address them here except insofar as they overlap with general criticisms of the KellylFrye rule as discussed below. Amici curiae’s various suggestions for improving or “fixing” the Kelly rule may well have merit, but the present case is not a good vehicle for addressing them. Likewise, we will not permit amici curiae to convert this relatively narrow HGN case into a vehicle for reviewing the DNA cases. We turn, then, to the commentators critical of the Frye formulation itself.
The critics of Frye focus primarily on its conservative nature: As previously noted, the doctrine contemplates an undefined period of testing and [602]study by a community of experts before a new scientific technique may be deemed “generally accepted,” thus delaying the admissibility of evidence derived from the technique. (See, e.g., Black, A Unified Theory of Scientific Evidence (1988) 56 Fordham L.Rev. 595, 636-637 [Black]; Giannelli, The Admissibility of Novel Scientific Evidence: Frye v. United States, a Half-Century Later (1980) 80 Colum. L.Rev. 1197, 1223-1224, 1248 [Giannelli]; Hanson, James Alphonzo Frye is Sixty-Five Years Old; Should He Retire (1989) 16 Western St. U. L.Rev. 357, 367-368 (Hanson); Note, Leading Cases, 101 Harv.L.Rev. 119, 125-127 (Harvard Note); Daubert, supra, 509 U.S. at p._, fns. 4, 5 [125 L.Ed. 2d at pp. 478-479], and articles cited.) These commentators observe that conceivably, a reliable, readily provable, technique could nonetheless remain unknown and untested by the relevant scientific community, thereby indefinitely delaying its use in the courtroom. (Hanson, supra, pp. 367-368.) One commentator observes that to the extent Frye excludes favorable defense evidence, it may be constitutionally deficient. (Harvard Note, supra, pp. 125-127.)
But we acknowledged the foregoing basis for criticism in Kelly, noting that “[s]ome criticism has been directed at the Frye standard, primarily on the ground that the test is too conservative, often resulting in the prevention of the admission of relevant evidence [citations].” (17 Cal.3d at pp. 30-31.) We nonetheless concluded that “there is ample justification for the exercise of considerable judicial caution in the acceptance of evidence developed by new scientific techniques.” (Id. at p. 31.) As we have previously indicated, Kelly set forth at length its reasons for adopting a more cautious approach to the admission of new scientific evidence. Nothing occurring in the years since Kelly was decided requires us to reconsider that conclusion.
Indeed, as late as 1989 we acknowledged that “[t]he courts are willing to forego admission of such techniques completely until reasonably certain that the pertinent scientific community no longer views them as experimental or of dubious validity. This all-or-nothing approach was adopted [in Kelly] in full recognition that there would be a '“considerable lag” ’ between scientific advances and their admission as evidence in a court proceeding. [Citation.]” (People v. Stoll (1989) 49 Cal.3d 1136, 1156 [265 Cal.Rptr. 111,783 P.2d 698].)
As previously noted, amicus curiae Attorney General criticizes Kelly on the additional ground that it requires the trial judge to defer admissibility questions to a “nose count” of scientists rather than allowing the judge or jury to directly confront the issue of the reliability of the evidence. But, as we observed in Kelly, it may be preferable to let admissibility questions regarding new scientific techniques be settled by those persons most qualified to assess their validity. (See 17 Cal.3d at p. 31.) Some commentators [603]have questioned the ability of trial judges, often wholly unschooled in scientific areas, to evaluate highly technical scientific material. As the Harvard Note, supra, observes, “The Frye rule ensures that judges and juries with little or no scientific background will not attempt to resolve technical questions on which not even experts can reach a consensus . . . .” (101 Harv. L.Rev. at p. 127, fn. omitted.)
Moreover, the criticism of Frye has been balanced by favorable commentary and widespread support. As we previously observed, both the defendant and the People herein (through the Orange County District Attorney) endorse Kelly as an essential check on the admissibility of new scientific techniques. Moreover, most critics of Frye acknowledge the test has several positive aspects and operates well in many situations. (See Hanson, supra, 16 Western St. U. L.Rev. at pp. 361-363, 458-460; Harvard Note, supra, 101 Harv.L.Rev. at p. 127; Black, supra, 56 Fordham L.Rev. at pp. 637-638.)
For example, the Hanson article lists the following positive features of the Frye doctrine: “(a) The time and cost of proving and establishing new scientific principles are transformed from a courtroom ... to a laboratory • • • • fiD (b) Each court thus need not confront the principle de novo, and may draw from other court decisions, the applicable literature, . . . and if offered, additional expert testimony .... [11 (c) Presumably a battery of well-qualified scientific and medical personnel are available to support the principle . . . .” (Hanson, supra, 16 Western St. U. L.Rev. at pp. 458-459.)
The Harvard Note is likewise predominantly favorable toward Frye. The author states that, “[djespite the[] criticisms, however, the Frye rule plays a vital role in the trial process . . . . [<fl] Although the Frye test may be difficult to apply and at times may exclude relevant evidence, it has proven its value for over sixty years. It has prevented justice from becoming a matter of amateur guesswork based on unreliable techniques and has helped to assure that determinations of guilt or innocence are not influenced by the vagaries of pseudoscience. [Frye is] . . . a wise rule that contributes greatly to the integrity of the criminal process.” (Harvard Note, supra, 101 Harv. L.Rev. at p. 127.)
Even Professor Giannelli, Frye's severest critic, acknowledges that Frye's requirement of a “special burden” as a prerequisite to admissibility of a new scientific technique has merit, and that if a “relevancy” test is chosen as an alternative (as in Daubert), special steps should be taken to assure the reliability of the evidence, including requiring the prosecutor to prove the validity of the technique beyond a reasonable doubt. (Giannelli, supra, 80 Colum. L.Rev. at pp. 1248-1250.)
[604]Despite the criticism of Kelly/Frye, this court has had numerous occasions to review and apply the doctrine, and has done so without apparent difficulty or critical comment. (See, e.g., People v. Diaz, supra, 3 Cal.4th at pp. 525-528 [tissue sample analysis]; People v. Pride (1992) 3 Cal.4th 195, 238-239 [10 Cal.Rptr.2d 636, 833 P.2d 643] [hair comparison analysis]; People v. Stoll, supra, 49 Cal.3d at pp. 1152-1161 [standardized personality tests]; People v. Bledsoe (1984) 36 Cal.3d 236, 245-251 [203 Cal.Rptr. 450, 681 P.2d 291] [rape trauma syndrome]; People v. Shirley, supra, 31 Cal.3d 18, 51-54 [hypnotically induced testimony].)
Additionally, we observe that the Legislature has had ample opportunity to amend the Evidence Code provisions to abrogate or modify the general acceptance standard that Kelly found implicit within them. The Legislature has made frequent amendments to the expert testimony provisions of that code since its adoption in 1965. (See, e.g., §§ 730-731 [appointment of experts], 795 [hypnosis testimony], 811-814 [market value evidence], former 892 [blood test evidence; later repealed].) Legislative failure to amend sections 720 or 801, although not conclusive, may be presumed to signify legislative acquiescence in our Kelly decision. (See People v. Escobar (1992) 3 Cal.4th 740, 750-751 [12 Cal.Rptr.2d 586, 837 P.2d 1100]; Bailey v. Superior Court (1977) 19 Cal.3d 970, 977 and fn. 10 [140 Cal.Rptr. 669, 568 P.2d 394]; Estate of McDill (1975) 14 Cal.3d 831, 837-839 [122 Cal.Rptr. 754, 537 P.2d 874].)
In sum, Kelly sets forth the various reasons why the more “conservative” Frye approach to determining the reliability of expert testimony regarding scientific techniques represents an appropriate one. Daubert, which avoided the issue of Frye's “merits,” presents no justification for reconsidering that aspect of our holding in Kelly. Thus, we conclude that the Kelly formulation survived Daubert in this state, and that none of the above described authorities critical of that formulation persuades us to reconsider or modify it at this time. Accordingly, we turn next to the question of the application of that standard to the facts of the present case.
5. HGN Test Is a New Scientific Test Under Kelly— After reviewing the briefs and applicable cases, we conclude the Court of Appeal correctly decided that the HGN test was a “new scientific technique” within the scope of the Kelly formulation, and for that reason proof was required of its general acceptance by the scientific community.
a. California HGN Decisions—The California decisions involving the HGN test do not address whether that test involves a “new scientific technique” within the scope of Kelly. (See People v. Williams, supra, 3 [605]Cal.App.4th 1326; People v. Ojeda, supra, 225 Cal.App.3d 404; People v. Loomis, supra, 156 Cal.App.3d Supp. 1.) Instead, these cases consider the general admissibility of police testimony regarding the results of HGN tests in particular cases, a matter we discuss in part 6 hereof, post.
Other decisions make clear that Kelly is applicable only to “new scientific techniques.” (See People v. Webb (1993) 6 Cal.4th 494, 524 [24 Cal.Rptr.2d 779, 862 P.2d 779]; People v. Stoll, supra, 49 Cal.3d 1136, 1155-1156; Kelly, supra, 17 Cal.3d at p. 30.) The People argue that HGN testing is neither “new” nor “scientific.” We disagree.
b. HGN Testing Is a “New” Technique—As we stated in Stoll, supra, 49 Cal.3d at page 1156, “KellylFrye only applies to that limited class of expert testimony which is based, in whole or part, on a technique, process, or theory which is new to science and, even more so, the law. “ (See also People v. Clark (1993) 5 Cal.4th 950, 1018 [22 Cal.Rptr.2d 689, 857 P.2d 1099] [allowing blood spatter evidence based on technique predating Kelly decision and derived from matters of common knowledge].)
In Stoll, supra, we observed that the standard psychological testing at issue in that case was “not new to psychology or the law . . . . [H California courts have routinely admitted defense expert opinion analogous to the one offered here, with no suggestion that KellylFrye applies. . . . [f] . . . Moreover, . . . diagnostic use of written personality inventories . . . has been established for decades. Modem courts have not resisted reference to these tests.” (49 Cal.3d at pp. 1157-1158.)
The People observe that HGN testing has been used by law enforcement agencies for more than 30 years. A 1988 annotation confirms that “[t]he horizontal gaze nystagmus (HGN) test has been in use for 30 years, but it has not been widely applied in the United States until recently.” (Annot., Horizontal gaze nystagmus test: use in impaired driving prosecution (1988) 60 A.L.R.4th 1129, 1131, italics added and fn. omitted.) This annotation observes that the HGN symptom was first recognized in the 1960’s in connection with barbiturate use, but the earliest court decision cited by the annotation as addressing the admissibility of HGN test results was decided in California in 1984 (People v. Loomis, supra, 156 Cal.App.3d Supp. 1), and that case disallowed the evidence.
In determining whether a scientific technique is “new” for Kelly purposes, long-standing use by police officers seems less significant a factor than repeated use, study, testing and confirmation by scientists or trained technicians. Unlike the psychiatric tests involved in Stoll, supra, 49 Cal.3d at pages [606115]7 to 1158, HGN testing has been repeatedly challenged in court, with varying degrees of success, in this and other states, and accordingly its courtroom use cannot fairly be characterized as “routine” or settled in law. (See Annot., supra, 60 A.L.R.4th 29, and cases cited; People v. Williams, supra, 3 Cal.4th at p. 1336, and cases cited.) Our survey of decisions from states that recognize the Frye standard indicates that, despite wide controversy regarding the admissibility of HGN evidence for purposes of establishing probable intoxication, most courts agree that HGN testing is subject to that standard.
Given the recent history of legal challenges to the admissibility of HGN test evidence in this and other states, it seems appropriate that we deem the technique “new” or “novel” for purposes of Kelly. To hold that a scientific technique could become immune from Kelly scrutiny merely by reason of long-standing and persistent use by law enforcement outside the laboratory or the courtroom, seems unjustified.
c. HGN Testing Is a “Scientific” Technique—In Stoll, we also observed that, by reason of the potential breadth of the term “scientific” in the Kelly/Frye doctrine, the courts often refer “to its narrow ‘common sense’ purpose, i.e., to protect the jury from techniques which, though ‘new,’ novel, or ‘ “experimental,” ’ convey a ‘ “misleading aura of certainty.” ’ [Citations.]” (49 Cal.3d at pp. 1155-1156.) According to Stoll, a technique may be deemed “scientific” for purposes of KellylFrye if “the unproven technique or procedure appears in both name and description to provide some definitive truth which the expert need only accurately recognize and relay to the jury.” (Id. at p. 1156, italics added.)
Defendant herein contends that the HGN test, both in “name” (“horizontal gaze nystagmus”) and “description” (observation of involuntary jerking of eyeball induced by ingestion of alcohol) fits Stoll’s definition of a scientific technique that provides the officer, and thus the jury, with supposedly “definitive” proof of intoxication. As noted in People v. Ojeda, supra, 225 Cal.App.3d at page 408, quoting from another case, ‘“[T]he principal obstacle to the admissibility of the horizontal gaze nystagmus test may be its pretentiously scientific name.’ ” A jury might be unduly swayed by HGN evidence solely by reason of its technical nomenclature.
Additionally, the HGN test, as described by the arresting officer in the present case, appears to provide to the jury a “definitive truth” wholly apart from its imposing name. The arresting officer in this case was asked what he “generally” did to determine whether or not a suspect was intoxicated. He responded, “Well, I—I check their nystagmus, that’s a big indicator for me.” [607]He continued by noting that the HGN test usually was one of the first sobriety tests he performed.
The arresting officer in the consolidated appeal of Michael Tatar, the transcript of which we take judicial notice, was even more authoritative regarding HGN testing. According to the officer, he has “always been right” whenever he checked his HGN test results with subsequent blood-alcohol test results.
Thus, the “aura of certainty” emanating from the officers’ description of HGN tests was unmistakable. A jury could be unduly and unjustifiably impressed by the confidence the testifying officers showed regarding the HGN procedure.
Defendant cites many cases from other states holding that HGN testing is a “scientific" technique for purposes of Frye analysis, and that, accordingly, expert testimony from persons other than the officers who administer the HGN tests is required to sustain its admissibility. (See State v. Barker (1988) 179 W.Va. [366 S.E.2d 642, 645]; State v. Superior Court (Blake) (1986) 149 Ariz. 269 [718 P.2d 171, 179-181] [hereafter Blake]', State v. Borchardt (1986) 224 Neb. 47 [395 N.W.2d 551, 559]; State v. Cissne (1994) 72 Wn.App. 677 [865 P.2d 564, 568] [hereafter Cissne]; State v. Witte (1992) 251 Kan. 313 [836 P.2d 1110, 1115-1116] [hereafter Witte]; Malone v. City of Silverhill (Ala.Crim.App. 1989) 575 So.2d 101, 105; People v. Vega (1986) 145 Ill.App.3d 996 [99 Ill.Dec. 808, 496 N.E.2d 501]; State v. Reed (1987) 83 Ore.App. 451 [732 P.2d 66, 68]; Com. v. Apollo (1992) 412 Pa.Super. 453 [603 A.2d 1023, 1026]; Com. v. Miller (1987) 367 Pa.Super. 359 [532 A.2d 1186, 1189].)
For example, in Witte, supra, the Kansas Supreme Court cited 11 decisions from other states holding that HGN testing is a “scientific” test requiring Frye compliance. (836 P.2d at p. 1115.) As stated in Witte, “The HGN test is distinguished from other field sobriety tests in that science, rather than common knowledge, provides the legitimacy for HGN testing. [Citations.] Certain reactions to alcohol are so common that judicial notice will be taken of them; however, HGN testing does not fall into this category. [Citation.] HGN test results are ‘scientific evidence based on the scientific principle that consumption of alcohol causes the type of nystagmus measured by the HGN test.’ [Citation.] HGN evidence could have a disproportionate impact on the jury’s decisionmaking process because of the test’s scientific nature and because the jury may not understand the nature of the test or the methodology of its procedure. [Citations.].” {Ibid.)
Thus, we conclude that HGN tests involve a “new scientific technique” that is required to meet Kelly's general acceptance test.
[6086]. Police Officer Testimony Is Insufficient to Establish General Acceptance— The People concede that “most states have determined the [HGN] test is a scientific test” under Frye. They nonetheless insist that testimony by the officers administering the HGN test is sufficient to establish Kelly compliance. They rely on our statement in People v. Stoll, supra, 49 Cal.3d at page 1157, that “absent some special feature which effectively blindsides the jury, expert opinion testimony is not subject to Kelly/Frye.” The People observe that the officers who administered the tests are subject to cross-examination, and that the jury is not likely to accord their opinions regarding HGN test results the same weight as a scientist’s opinion on the same subject. According to the People, field sobriety tests such as the HGN test merely “rely on the experience of a police officer in observing the performance of persons who may or may not be intoxicated. . . . There is nothing more scientific about the HGN test than the other field sobriety tests.”
The People also rely on language in People v. Ojeda, supra, 225 Cal.App.3d at page 408, that “police officers who deal daily with intoxicated persons become expert at recognizing the physical effects of intoxication .... This does not make them scientists.” The People cite cases from other states holding either that the HGN test is not a “scientific” test or that the testimony of police officers regarding administration of the HGN test is sufficient compliance with the Frye standard. (See City of Fargo v. McLaughlin (N.D. 1994) 512 N.W.2d 700, 706-707; State v. Garrett (1991) 119 Idaho 878 [811 P.2d 488, 491-493]; State v. Sullivan (S.C. 1993) 426 S.E.2d 766; State v. Bresson (1990) 51 Ohio St.3d 123 [554 N.E.2d 1330, 1334]; State v. Armstrong (La.Ct.App. 1990) 561 So.2d 883, 885-887; see also State v. Clark (1988) 234 Mont. 222 [762 P.2d 853, 856-857] [allowing HGN evidence by police, officer; Frye test not adopted in state]; State v. Murphy (Iowa 1990) 451 N.W.2d 154, 156-157] [same]; Whitson v. State (1993) 314 Ark. 458 [863 S.W.2d 794, 798] [same]; Emerson v. State (Tex.Crim.App. 1994) 880 S.W.2d 759, 768-769 [same]; State v. O’Key (1993) 123 Ore.App. 54 [858 P.2d 904, 907-908] [same].)
The foregoing decisions, however, do not explain how police officers are competent to establish general acceptance of HGN testing in the scientific community, or how they are qualified to relate the scientific bases underlying the nystagmus test. As stated in People v. Williams, supra, 3 Cal.App.4th at pages 1333 to 1334, “We will assume that [officer] Vega’s training and experience qualified him as an expert to administer the nystagmus test and observe signs of nystagmus. Being qualified to attribute the observed eye movements to a particular cause, however, is a far different matter. ...['][] Vega’s opinion that appellant was under the influence of alcohol, to the [609]extent it was based on the nystagmus test, rests on scientific premises well beyond his knowledge, training, or education. Without some understanding of the processes by which alcohol ingestion produces nystagmus, how strong the correlation is, how other possible causes might be masked, what margin of error has been shown in statistical surveys, and a host of other relevant factors, Vega’s opinion on causation, notwithstanding his ability to recognize the symptom, was unfounded. It should have been excluded.”
Consistent with both the weight of authority and the cautious, “conservative” nature of Kelly, we conclude that testimony by police officers regarding the mere administration of the test is insufficient to meet the general acceptance standard required by Kelly.
The People urge, however, that we take judicial notice of the various decisions (e.g., Blake, supra, 718 P.2d at pp. 179-181; People v. Buening (1992) 229 Ill.App.3d 538 [170 Ill.Dec. 542, 592 N.E.2d 1222, 1227]; State v. Garrett, supra, 811 P.2d at pp. 490-493; State v. Hill (Mo.Ct.App. 1993) 865 S.W.2d 702, 704-705) and published studies concluding that HGN testing meets the Frye standard. But the conclusions of those decisions and studies are by no means unchallenged, for there appears to exist substantial opposing authority. (See Witte, supra, 836 P.2d at pp. 1119-1121, citing numerous articles and studies; Cissne, supra, 865 P.2d at p. 568, and fh. 5.)
Witte, decided in 1992, suggests that if the Arizona Supreme Court in Blake had been aware of the contrary authority and evidence, it might not have held that HGN testing satisfied Frye. (836 P.2d at p. 1121.) The 1994 Cissne decision likewise observed that “[a]s Witte noted, research and articles critical of HGN testing appeared after some jurisdictions concluded that HGN testing satisfied Frye standard[s].” (865 P.2d at p. 568.) Cissne concluded, “[w]e decline the State’s invitation to follow those few jurisdictions that have concluded that HGN testing meets the Frye standard. The trial court must evaluate, weigh and consider the conflicting evidence before determining whether the test is novel, and, if it is novel, whether it is reliable . . . .” {Id. at p. 569.)
Additionally, we note that several decisions from other states have refused to resolve the Frye issue on appeal by reference to scientific studies and articles not introduced at the defendant’s trial. (See Com. v. Miller, supra, 532 A.2d at p. 1190; People v. Vega, supra, 496 N.E.2d at pp. 504-505; State v. Barker, supra, 366 S.E.2d at p. 646; State v. Reed, supra, 732 P.2d at p. 69.) Although theoretically we could attempt to weigh and evaluate the merits of the conflicting authority, it seems more appropriate to remand this issue to a trial court for an evidentiary hearing, as several other decisions [610]have suggested. (E.g., State v. Barker, supra, 366 S.E.2d at p. 646; Cissne, supra, 865 P.2d at p. 569; Witte, supra, 836 P.2d at p. 1121; see also People v. Brown (1985) 40 Cal.3d 512, 533-535 [220 Cal.Rptr. 637, 709 P.2d 440] [explaining our reluctance to determine on appeal general acceptance of electrophoresis technique on basis of available scientific literature, without “an adequate future trial record made with the help of live witnesses qualified in the applicable scientific disciplines”].)
As stated in Witte, “The reliability of the HGN test is not currently a settled proposition in the scientific community. . . . Before this court rules on whether HGN evidence satisfies the Frye admissibility requirements, a trial court first should have an opportunity to examine, weigh, and decide disputed facts to determine whether the test is sufficiently reliable to be admissible for any purpose in Kansas.” (836 P.2d at p. 1121.) We agree with that analysis and, accordingly, we deny the People’s application for judicial notice.
7. Limited Remand Appropriate— In accord with our foregoing discussion, we conclude that the Court of Appeal was correct in reversing both counts of defendant’s conviction, for no evidence was elicited to show that HGN testing had been generally accepted in the scientific community, and the error was clearly prejudicial. As the Court of Appeal concluded, “it is reasonably probable a different result would have been achieved on both counts but for the HGN evidence [citation]. Leahy passed the other field sobriety tests. His blood-alcohol level was said to be .10, only .02 over the statutory maximum; and criminalists generally concede a margin of error of at least plus or minus .01. Also, the passage of time between arrest and test can account for even more than that, up or down. About 90 minutes went by between arrest and Leahy’s encounter with the intoxilyzer. Depending on when he had his last drink and a host of other factors, his blood-alcohol level could have risen or fallen several points in that time.”
We accept, however, the People’s suggestion that an entire retrial of the case may be unnecessary. Instead, we will direct the Court of Appeal to reverse defendant’s conviction and remand the case to the trial court for a Kelly hearing in accordance with our opinion. If, at the conclusion of the hearing, the trial court concludes there is sufficient basis to admit the HGN testimony previously presented, the court should reinstate the judgment without reintroducing such testimony. If the trial court determines the HGN evidence is inadmissible under Kelly, the court should order a new trial if the People so elect. If the judgment of conviction is reinstated, or a new trial ordered, appellate review will be available to the respective parties regarding the trial court’s ruling, limited to any new issues not resolved in this opinion. [611](See People v. Collins (1986) 42 Cal.3d 378, 394-395 [228 Cal.Rptr. 899, 722 P.2d 173] [remand procedure for determining prejudice from errors arising under People v. Castro (1985) 38 Cal.3d 301 [211 Cal.Rptr. 719, 696 P.2d 111]; judgment on remand subject to appeal by both parties]; cf. People v. Pizarro (1992) 10 Cal.App.4th 57, 95-96 [12 Cal.Rptr.2d 436] [.Kelly/Frye remand].)
Defendant objects to this limited remand procedure, contending that even if Kelly were deemed satisfied, the question would remain whether police officers were qualified to testify regarding the HGN results. We reject this contention. Once it has been shown that HGN testing is generally accepted in the scientific community, no reason exists why police officers should be deemed unqualified to administer and report the results of those tests. Thus, in future cases, once the Kelly standard has been met, as reflected by a published appellate precedent, the prosecution will not be required to submit expert testimony to confirm a police officer’s evaluation of an HGN test. Of course, nothing would prevent the defendant from challenging that evaluation with expert testimony of his own.
8. Establishing General Acceptance— Because the issue may arise on remand, we briefly comment on one aspect of the Kelly formulation that some amici curiae have found troublesome. In Kelly, quoting with approval from Frye, we indicated that a new scientific technique must be “ ‘sufficiently established to have gained general acceptance in the particular field to which it belongs.’ ” (17 Cal.3d at p. 30, italics removed.) We further suggested it was “questionable whether the testimony of a single witness alone is ever sufficient to represent, or attest to, the views of an entire scientific community,” and we observed that “[i]deally, resolution of the general acceptance issue would require consideration of the views of a typical cross-section of the scientific community, including representatives, if there are such, of those who oppose or question the new technique.” {Id. at p. 37, italics added.)
Thereafter, in People v. Shirley, supra, 31 Cal.3d at pages 55 and 56, we indicated that “considerations of judicial economy” would permit a court to scrutinize “published writings in scholarly treatises and journals” in lieu of live testimony. We added that the burden of showing general acceptance lies with the proponent of the evidence to show a “scientific consensus” (italics added), and that “if a fair overview of the literature discloses that scientists significant either in number or expertise publicly oppose [the technique] as unreliable, the court may safely conclude there is no such consensus at the present time.” (Id. at p. 56.) We concluded in Shirley that “it. . . appears [612]that major voices in the scientific community oppose the use of hypnosis to restore the memory of potential witnesses . . . {Ibid., italics added.)
We do not read Shirley as modifying or abandoning Kelly's insistence on ascertaining, if possible, whether the technique has become generally accepted by a “typical cross-section” of the relevant scientific community. Shirley's requirement of a “scientific consensus” by “major voices in the scientific community” seems entirely consistent with Kelly in this regard.
A few years later, in People v. Guerra, supra, 37 Cal.3d 385, we expounded briefly regarding Kelly's general acceptance test, noting that the Frye test does not demand “absolute unanimity of views in the scientific community .... Rather, the test is met if use of the technique is supported by a clear majority of the members of that community.” (37 Cal.3d at p. 418, italics added.) Guerra likewise seems quite consistent with both Kelly and Shirley. Kelly itself, at one point, described the Frye test as calling for “substantial agreement and consensus in the scientific community.” (See 17 Cal.3d at p. 31.) Of course, the trial courts, in determining the general acceptance issue, must consider the quality, as well as quantity, of the evidence supporting or opposing a new scientific technique. Mere numerical majority support or opposition by persons minimally qualified to state an authoritative opinion is of little value under the foregoing cases.
9. Summary and Conclusions—We conclude as follows:
(a) Our Kelly doctrine survived Daubert and continues to represent the standard by which new scientific techniques should be measured before evidence derived therefrom may be admitted in court.
(b) HGN testing is a new scientific technique requiring compliance with Kelly.
(c) Kelly contemplates appropriate expert testimony and evidence showing that HGN testing is generally accepted by a typical cross-section of the relevant scientific community. Until compliance with Kelly is demonstrated, testimony of police officers who merely administer HGN tests is, by itself, inadequate for this purpose.
(d) “General acceptance” under Kelly means a consensus drawn from a typical cross-section of the relevant, qualified scientific community.
The judgment of the Court of Appeal reversing defendant’s conviction is affirmed, and the Court of Appeal is directed to remand the case to the trial [613]court for a Kelly hearing in accordance with our opinion. If, at the conclusion of the hearing, the trial court concludes there is sufficient basis to properly admit the HGN testimony previously presented, the court should reinstate the judgment. If the trial court determines the evidence is insufficient to properly admit the testimony presented, then the court should order a new trial, if the People so elect. If the judgment is reinstated, or a new trial ordered, appellate review will be available to the parties regarding the trial court’s ruling, limited to any new issues not previously resolved in this opinion.
Mosk, J., Kennard, J., Arabian, J., George, J., and Werdegar, J., concurred.