Kim E. LOGERQUIST, a single woman, Petitioner. v. Hon. Michael R. McVEY, Judge of the Superior Court of the State of Arizona, in and for the County of Maricopa, Respondent Judge, John T. Danforth, M.D. and Mary Jean Danforth, his wife; John T. Danforth, P.C., Real Parties in Interest, 196 Ariz. 470

OPINION FELDMAN, Justice. ¶ 1 Applying the rule of Frye v. United States, 293 F. 1013 (D.C.Cir.1923), the trial judge entered an order precluding “expert testimony of Plaintiffs alleged repressed memory.” We granted review to clarify Rule 702, Arizona Rules of Evidence, which governs the admission of opinion testimony. ¶2 The construction and application of Rule 702 has become an issue of nationwide concern following the United States Supreme Court’s opinion in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993).

Daubert and its progeny reject the Frye test and construe Rule 702, Federal Rules of Evidence, to create a “gatekeeper” function for federal judges. The question of whether to apply Frye or Daubert to Ariz.R.Evid. 702 appears with increasing frequency and creates uncertainty in this and many other cases pending in our trial courts. To settle this policy question for Arizona courts, we take the rare step of reviewing the propriety of the trial court’s interlocutory order. See Piner v. Superior Court, 192 Ariz. 182, 184-85, 962 P.2d 909, 911-12 (1998); Summerfield v.

Superior Court, 144 Ariz. 467, 469, 698 P.2d 712, 714 (1985). We have jurisdiction under Arizona Constitution art. VI, § 5(4). FACTS AND PROCEDURAL HISTORY ¶ 3 Kim Logerquist (Plaintiff) alleges that her pediatrician (Defendant) sexually abused her on several occasions between 1971 and 1973, when she was eight to ten years old. Plaintiff further alleges that she had amnesia about those events until 1991, when her memory was triggered by watching a television commercial featuring a pediatrician.

She sought “to introduce evidence, through expert testimony, that severe childhood trauma, including sexual abuse, can cause a repression of memory, and that in later years this memory can be recalled with accuracy.” Minute Entry Order, June 11, 1998, at 1 (hereafter June 11 Order). ¶ 4 Over objection, the trial judge granted Defendant’s motion that a Frye hearing be held to assess the admissibility of expert testimony regarding repressed memory. Two experts testified at this hearing. Plaintiff called Dr. Bessell van der Kolk, a clinical psychiatrist who specializes in dissociative amnesia.

He testified regarding the large number of patients who alleged such phenomenon and about his diagnoses of dissociative amnesia or post-traumatic stress disorder in such patients. He would testify, among other things, that his experience and observations over many years, together with the extensive literature on the subject, have led him to conclude the phenomenon exists in some patients. Defendant’s expert, Dr.

Richard Kihlstrom, a research psychologist, testified there were serious flaws in the many studies supporting repressed memory and cited other studies finding trauma usually enhances memory rather than causes amnesia.

Doctor Kihlstrom did not, however, have any personal experience treating or dealing with people claiming to suffer from repressed memory; nor had he participated in any studies on trauma’s effect on memory. ¶ 5 After a lengthy hearing, the trial judge determined the “theories advanced by Plaintiffs experts are not generally accepted in the relevant scientific community of trauma memory researchers.” June 11 Order, at 4.

The judge therefore “ORDERED excluding expert testimony of Plaintiffs alleged repressed memory, and Plaintiffs theory that such evidence can be recalled with accuracy.” Id. ¶ 6 Because this interlocutory order was not appealable, Plaintiff sought review by special action in the court of appeals. See Rule 1, Arizona Rules of Procedure for Special Actions. The court of appeals declined jurisdiction, and Plaintiff sought review by this court. We granted review for the reasons stated at the beginning of this opinion, allowed supplemental briefing, and heard oral argument.

The first question accepted for review was whether Frye or Daubert applied. We conclude Frye was inapplicable and reject Daubert as it has been interpreted in the cases that have followed it. We now vacate the order excluding expert testimony. DISCUSSION A. Contentions of the parties ¶7 Plaintiff contends the June 11 Order, based on the Frye principle, is incorrect because Frye is inapplicable. If the Frye test were applicable to the evidence Plaintiff seeks to adduce, Plaintiff argues that it should be discarded in favor of Daubert’s test of reliability.

Defendant, on the other hand, believes that Frye applies to the testimony and the trial judge correctly concluded the principles explained by Doctor van der Kolk had not gained general acceptance, so that expert testimony regarding these principles was therefore inadmissible. In the event Frye is found to be inapplicable or is abandoned by this court, Defendant argues that the Daubert test should be applied and the trial judge had discretion as “gatekeeper” to preclude the evidence. ¶8 Other courts have reached conflicting decisions on these questions. See, e.g., Shahzade v.

Gregory, 923 F.Supp. 286 (D.Mass.1996) (applying Daubert but finding general acceptance and admitting evidence); Wilson v. Phillips, 73 Cal.App.4th 250, 86 Cal.Rptr.2d 204 (1999) (Frye inapplicable, testimony like Dr. van der Kolk’s admissible under expert evidence rule); Doe v. Shults-Lewis Child & Family Serv., Inc., 718 N.E.2d 738, 750 and n. 1 (Ind.1999) (applying Daubert but refusing “to declare repressed memory syndrome unreliable”); New Hampshire v. Hungerford, 142 N.H. 110, 697 A.2d 916 (1997) (applying Frye and precluding evidence); New Mexico v.

Alberico, 116 N.M. 156, 861 P.2d 192 (N.M.1993) (applying Daubert but finding general acceptance and admitting evidence); Rhode Island v. Quattrocchi, 1999 WL 284882 (R.I.Super. April 26, 1999) (applying Frye and precluding evidence); Moriarty v. Garden Sanctuary Church of God, 334 S.C. 150, 511 S.E.2d 699 (App.1999) (dissociative amnesia or repressed memory syndrome valid theory under South Carolina standard for admission of scientific evidence). B. Proceedings in the trial court ¶ 9 We think it necessary to focus on the precise controversy as defined by the record before the trial court.

Plaintiffs complaint, filed more than twenty years after the incidents and ten years after Plaintiff became an adult, initially raised questions regarding timeliness. The trial judge first granted Defendant’s motion to dismiss on the basis that the action was barred by the statute of limitations. Our court of appeals reversed that order, without resolving the Frye issue, and remanded for proceedings not inconsistent with its opinion. Logerquist v. Danforth, 188 Ariz. 16, 23-24, 932 P.2d 281, 288-89 (App. 1996).

We denied review, with Justice Mar-tone voting to grant. ¶ 10 On remand, and after extensive discovery, Defendant filed a Motion for Eviden-tiary Hearing Pursuant to Frye v. United States (hereafter Frye Motion). Defendant argued that Plaintiffs ease is based on scientific theories that are not readily accepted by the medical and scientific communities. Further, he contended the memories alleged were not real or accurate but had been distorted, implanted, or suggested by improper techniques used by the physician and psychologist treating Plaintiff for emotional problems.

Because the “medical community is unwilling to make a statement that there is scientific foundation for the accuracy of Ms. Logerquist’s claims, it would be inappropriate to allow her to proceed forward to trial.” Frye Motion at 14 (emphasis added). ¶ 11 In response, Plaintiff objected to a Frye hearing. As permitted by Ariz.R.Evid. 702, Plaintiffs treating doctors would testify to experience and observation with this and many other cases dealing with repressed memory, dissociative amnesia, and post-traumatic stress disorder.

Even if they gave general testimony based on the literature covering the subject, and if such testimony were subject to Frye, they could show general acceptance need not be non-controversial or universal. Conceding that not all allegedly recovered memories are accurate or truthful, Plaintiff argued that the question of the accuracy and credibility of her recollection was for the jury. ¶ 12 In his reply to Plaintiff’s response to the Frye Motion, Defendant argued that: Plaintiff alleges she suffers from dissociative amnesia....

The manual in which ‘Dissociative Amnesia’ is defined also indicates: There are no tests or set of procedures that invariably distinguish Dissociative Amnesia from Malingering, but individuals with Dissociative Amnesia usually score high on standard measures of hyp-notizability and dissociative capacity.

Malingered amnesia is more common in individuals presenting with acute, florid symptoms in a context in which potential secondary gain is evident — for example, financial or legal problems____ Care must be exercised in evaluating the accuracy of retrieved memories, because the informants are often highly suggestible. There has been considerable controversy concerning amnesia related to reported physical or sexual abuse, particularly when abuse is alleged to have occurred during early childhood.

Some clinicians believe that there has been an underreporting of such events, especial ly because the victims are often children and perpetrators are inclined to deny or distort their actions. However, other clinicians are concerned that there may be overreporting, particularly given the unreliability of childhood memories. There is currently no method for establishing with certainty the accuracy of such retrieved memories in the absence of corroborative evidence.

Reply in Support of His Motion for Eviden-tiary Hearing Pursuant to Frye (quoting American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders IV § 300.12 (1994) (hereafter DSM-IV)). ¶ 13 These pleadings were followed by a veritable blizzard of paper. Having received a witness list naming Doctor van der Kolk as Plaintiffs independent (non-treating) expert, Defendant sought by motion to preclude Doctor van der Kolk from testifying about the results of animal studies. A separate motion sought to preclude the doctor from giving any testimony that relied on his own clinical experience.

These were accompanied by a motion to preclude Doctor van der Kolk from relying on the literature listed in his letter to Plaintiffs counsel. Defendant also moved to preclude the testimony of Plaintiffs treating doctors, sought an order permitting him to provide additional material to assist the court in its evaluation of Doctor van der Kolk’s testimony, and moved to strike an affidavit filed in opposition to Defendant’s motion for

summary judgment because it contained expert opinion. ¶ 14 Defendant argued that expert opinion was inadmissible, no matter what its basis or the subject to which it was directed — whether repressed memory, dissociative amnesia, or post-traumatic stress disorder. Defendant maintained that view in arguing to this court.

Plaintiffs position, on the other hand, was set forth in her response to Defendant’s Memorandum to Assist the Court in Evaluating the Admissibility of Expert Evidence: This Response shows that Dr. van der Kolk’s personal experiences and observations in treating hundreds of survivors of childhood sexual abuse (CSA) that have total or partial amnesia of the CSA are not subject to the Frye rule.

The Response will further show that Dr. van der Kolk should be allowed to testify ... that when some CSA victims do have delayed memories, that their memories are as reasonably accurate as normal memories, if not better. ¶ 15 Doctor van der Kolk’s February 8, 1998 letter to counsel gives an even better picture of what Defendant sought to preclude: I hereby accept you[r] invitation to testify....

I intend to testify that amnesia for traumatic experiences, including for sexual abuse, has been documented in numerous scientific reports for over a century, and that this notion is, in fact, so well accepted in the relevant scientific community that it has not only been incorporated in the Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association within the very criterion set for Post Traumatic Stress Disorder, but also under a separate rubric of Dissociative Amnesia.

It has been further amplified in the official statement of the American Psychiatric Association on Memories of Childhood Sexual Abuse. I am the Director of the Trauma Center in Brookline, MA, which specializes in the treatment and research of individuals who suffer from the psychological effects of trauma. I have conducted numerous studies on the nature of the human response to trauma, including specifically on memory processes in responses. ¶ 16 The letter then listed some of the articles and books Doctor van der Kolk planned to rely on in his testimony.

The extensive bibliography that followed has been described in footnote 2, supra. Included were cites to seven items written by Doctor. van der Kolk himself. Almost all were articles published in prestigious, peer-reviewed journals such as the Harvard Review of Psychiatry and the American Journal of Psychiatry. Doctor van der Kolk’s qualifications were also of record. See Appendix A.

They clearly establish his extensive education, training, and experience in psychology and psychiatry and specifically in the study and treatment of dissociative amnesia. ¶ 17 It is apparent we are not dealing with an alchemist attempting to change lead into gold or an astrologer predicting events from the movements of the stars but one of the leading researchers and authorities in behavioral science. It would be strange that a witness so well qualified and experienced would not be permitted to testify on an issue beyond the experience of the average juror.

Nevertheless, the trial judge’s June 11 Order was quite broad. He first cited to DSM-IV § 300.12 “to support [Plaintiffs] contention that dissociative amnesia is generally accepted in the relevant scientific community.” However, the judge noted, that same

section provides the cautionary note previously quoted in ¶ 12. After reviewing similar cautionary notes in other studies, the judge concluded: Finally, this Court has carefully considered the various studies relied upon by Plaintiffs expert. Studies in the area of the effect of trauma upon memory are in their infancy. This Court has concluded that these studies contain serious methodological flaws, and that these flaws have prevented Plaintiffs theory from being generally accepted in the relevant scientific community of trauma memory researchers.

These methodological flaws include, but are not limited to, inadequate sample sizes, gender bias, consideration of other reasons for loss of memory (i.e., infantile amnesia), and perhaps most importantly, independent corroboration that the event alleged to have been forgotten, actually occurred. For the reasons set forth above, this Court has concluded that the theories advanced by Plaintiffs experts are not generally accepted in the relevant scientific community of trauma memory researchers.

Therefore, IT IS ORDERED excluding expert testimony of Plaintiffs alleged repressed memory, and Plaintiffs theory that such evidence can be recalled with accuracy. June 11 Order (emphasis added). ¶ 18 As Defendant indicated at argument, this order not only precluded Doctor van der Kolk’s testimony but effectively precluded that of Plaintiffs treating physicians.

Even assuming Plaintiff would be allowed to testify about her memory, this left her in the pragmatically impossible situation of having no evidence to support her testimony but nevertheless having to persuade the jury that she had suffered dissociative amnesia and that her recall could have been accurate. On the other hand, Defendant would presumably be able to call his expert to testify that Plaintiffs recollection was incredible or, at best, inaccurate. The preclusion order, in other words, as effectively took the ease from the jury as if the judge had granted

summary judgment or directed a verdict. We turn, therefore, to consider the legal propriety of the June 11 Order. C. Was Frye properly applied ¶ 19 By its own words, Frye applies to the use of novel scientific theories or processes to produce results. At the outset, we note that neither Plaintiff nor her lawyers argue that any scientific principle or process can be used to produce memories that are always or often accurate.

As a matter of scientific principle, one may now say that E always equals MC2, but Plaintiff does not claim that some scientific process, theory, or formula may be applied to test whether her memories of having been molested are true and accurate or whether the memories were imagined, suggested, implanted, or even, to put it tactfully, invented. One may or may not believe Plaintiff.

The effect of the June 11 Order is to practically ensure Plaintiffs testimony will not be believed because she will not be allowed to present expert evidence to describe or support the possible existence or diagnosis of repressed memory or dissociative amnesia. ¶20 We believe, however, that the truth of Plaintiffs testimony that she actually and accurately recalled or remembered the events, as distinguished from inventing them or having had them suggested or implanted, is for a jury to decide.

While Defendant contends the alleged loss of memory and consequent delay in reporting make Plaintiffs testimony unworthy of belief, in this, as in other cases, Rule 702 allows Plaintiff to call expert witnesses to explain her behavior following the events alleged and to help the jury determine whether Plaintiffs memories are real and accurate or imagined. We have so held on just such issues in the criminal law. ¶ 21 In State v.

Lindsey, for example, we dealt with the question of expert testimony regarding “behavior patterns of victims of ‘in-home incestuous-type [child] molesting.’ ” 149 Ariz. 472, 473, 720 P.2d 73, 74 (1986). The court of appeals noted that the evidence was offered to explain why child victims of incest may not reveal the events until long after the occurrence and why they may recant. State v. Lindsey, 149 Ariz. 493, 495-96, 720 P.2d 94, 96-97 (App.1985).' The trial judge overruled defendant’s Frye objection to the opinion evidence. Lindsey, 149 Ariz. at 476, 720 P.2d at 77.

The Martone dissent makes much of the fact that the expert testimony was based on “recognized principles of social and behavioral science.” But Doctor van der Kolk’s testimony is similarly based on principles of social and behavioral science recognized by clinicians. There was no Frye hearing in Lindsey.

Defendant’s Frye objection was overruled because the judge “determined Doctor Baker was qualified to testify because she had practiced” in the field, “saw patients” suffering from child sexual abuse, consulted with state agencies and case workers, and made “decisions and plans on specific cases [as well as doing] psychological evaluation of child victims and [having] seen over 100 victims, mostly in the family-type situation.” Id. at 497, 720 P.2d at 98.

We had the following comment regarding the propriety of admitting such testimony: The trial judge has discretion to allow such expert testimony [under Rule 702] where it may assist the jury in deciding a contested issue, including issues pertaining to accuracy or credibility of a witness’ recollection or testimony. The trial judge may exercise this discretion where there is a reasonable basis to believe that the jury will benefit from the assistance of expert testimony that explains recognized principles of social or behavioral science which the jury may apply to determine issues in the case.

Testimony of this type is not to be permitted in every case, but only in those where the facts needed to make the ultimate judgment may not be within the common knowledge of the ordinary juror. [T]he court of appeals correctly concluded that the trial court did not abuse its discretion in permitting ... testimony on general patterns of behavior. We cannot assume that the average juror is familiar with the behavioral characteristics of victims of child molesting. Knowledge of such characteristics may well aid the jury in weighing the testimony of the alleged child victim.

Children who have been the victims of sexual abuse or molestation may exhibit behavioral patterns (e.g. recantation, conflicting versions of events, confusion or inarticulate descriptions) which jurors might attribute to inaccuracy or prevarication, but which may be merely the result of immaturity, psychological stress, societal pressures or similar factors as well as of their interaction. Id. at 473-74, 720 P.2d at 74-75 (citations omitted); see also State v. Moran, 151 Ariz. 378, 728 P.2d 248 (1986). ¶ 22 In State v. Roscoe, we again dealt with behavioral evidence, though of a much different sort.

We held a dog handler’s opinion on the alleged ability of his tracking dog to identify scent long after it was laid down was admissible and Frye inapplicable. 145 Ariz. 212, 219-20, 700 P.2d 1312, 1319-20 (1984). We explained: The evidence here was not bottomed on any scientific theory. In fact, it appears that no one knows exactly how or why some dogs are able to track or scent, or the degree to which they are able to do so. No attempt was made to impress the jury with the infallibility of some general scientific technique or theory.

Rather, this evidence was offered on the basis that it is common knowledge that some dogs, when properly trained and handled, can discriminate between human odors. Preston’s testimony was premised upon this simple idea and was not offered as a product of the application of some accepted scientific process, principle, technique or device. It was offered as Preston’s opinion of the meaning of his dog’s reaction; that opinion was based upon Preston’s training of and experience with the dog.

The weight of the evidence did not hinge upon the validity or accuracy of some scientific principle; rather, it hinged on Preston’s credibility, the accuracy of his past observation of the dog’s performance, the extent of the train-, ing he had given the dog, and the reliability of his

interpretations of the dog’s reactions. It was not the theories of Newton, Einstein or Freud which gave the evidence weight; if so, the Frye test should have been applied. It was, rather, Preston’s knowledge, experience and integrity which would give the evidence weight and it was Preston who was available for cross-examination. His credentials, his experience, his motives and his integrity were effectively probed and tested. Determination of these issues does not depend on science; it is the exclusive province of the jury. Id. (citations omitted); see also Brooks v.

Colorado, 975 P.2d 1105 (Colo.1999) (similar experience-based testimony subject to Rule 702 analysis, not Frye); Louisiana v. Catanese, 368 So.2d 975 (La.1979) (excluding polygraph evidence using equivalent of Ariz. R.Evid. 702). It turned out that the witness presenting the dog-scent evidence in Roscoe was a charlatan. See State v. Roscoe, 184 Ariz. 484, 910 P.2d 635 (1996) (Roscoe II). But neither Rule 702 (with or without Frye), Daubert/Kumho, nor any other system can guarantee the validity of any particular evi-dentiary ruling.

Just as the refusal to apply Frye to Preston’s dog-scent evidence led to the admission of false testimony, so the application of Frye or Daubert could well have led to the exclusion of testimony from Einstein or Freud, both of whom advanced theories not generally accepted for many years. See Clifford M. Will, Was Einstein Right? (1986). ¶23 In State v. Hummert, we held that expert opinion on probability percentages based on computations derived from DNA statistics was inadmissible under Frye because the statistical bases and resultant formulae applied to reach the conclusion were not yet generally accepted.

The expert’s opinion — the final result — was based on a process or formula established by others and not generally acknowledged by scientists and statisticians in that field. 188 Ariz. 119,124-25, 933 P.2d 1187, 1192-93 (1997). But we also held that the expert could relate his experience in the field to the facts and that an opinion based on his observations and experience would be admissible. Id. at 125, 933 P.2d at 1193. This was not, as the Martone dissent claims, because the DNA principle passed the Frye test. See Martone dissent at ¶ 83.

It was, rather, because the opinions offered on random match frequency, while not generally accepted, passed the Ariz.R.Evid. 702 test of witness observation and experience. We explained: The experts’ testimony in the present case involved two types of evidence — scientific evidence on the procedures for determining a match between evidentiary DNA and opinion evidence concerning the experts’ experience with random matches. The trial judge properly applied the Frye analysis and determined that evidence of a match is admissible.

However, on the basis of the . scientific evidence then available, the judge did not allow the experts to testify about the mathematical or statistical probability resulting from the match. Instead, the experts were allowed to offer evidence of their personal opinion.

This testimony is governed not by the application of Frye but by Arizona Rules of Evidence 702 and 703. “Frye-ing” scientific evidence is necessary when application of a scientific technique is “likely to have an enormous effect in resolving completely a matter in controversy.” However, when the expert gives testimony that “only helps a trier to interpret the evidence ... it will be received on a lesser showing of scientific certainty.” As we stated in Roscoe, “[t]he weight of the evidence did not hinge upon the validity or accuracy of some scientific principle; rather, it hinged on [the expert’s] credibility, the accuracy of his past observation ... the extent of the training ... and the reliability of his

interpretations____” The experts in this case did not testify to conclusions based on the application of Cell-mark’s statistics and database but only to their own' experience. Having made the DNA examination according to recognized scientific principles and finding a match at three loci, the experts claimed that because of the unique nature of each person’s DNA, they had never before seen a three-loci match from unrelated individuals. On the basis of their own experience, they believed such a random match would be very uncommon.

The trial judge did not err in admitting this evidence of the experts’ own work and experience and the opinions reached on that basis. See Ariz. R.Evid. 702 and 703. Id. at 124-25, 933 P.2d at 1192-93 (citations omitted). ¶ 24 Many cases in our courts, and in those of other states with rules similar to our Ariz. R.Evid. 702, reach similar conclusions in dealing with expert opinion in matters of behavioral science. Our court of appeals concluded that Frye was inapplicable to expert testimony on child sexual abuse accommodation syndrome (CSAAS). State v. Vare-la, 178 Ariz. 319, 873 P.2d 657 (App.1993).

The court remarked that “testimony concerning general characteristics of child sexual abuse victims is not ‘new, novel or experimental scientific evidence’ and therefore does not require the additional screening provided by Frye.” Id. at 325-26, 873 P.2d at 663-64 (quoting People v. Stoll, 49 Cal.3d 1136, 265 Cal.Rptr. 111, 783 P.2d 698, 714 (1989)); see also State v. Tucker, 165 Ariz. 340, 346, 798 P.2d 1349, 1355 (App.1990) (behavioral characteristics of child molesters and victims); State v.

Stowers, 81 Ohio St.3d 260, 690 N.E.2d 881 (1998) (Frye inapplicable to expert’s testimony that alleged child victim’s behavior, including delayed disclosure and recantation, is consistent with behavior expert observed in victims of CSAAS). ¶ 25 Of course in Varela and Tucker, as in the other cases cited, the testimony was not offered as direct proof that sexual abuse occurred but as an explanation of behavior that would help the jury understand the evidence and determine whether the charge was true. See also Frenzel v.

Wyoming, 849 P.2d 741 (Wyo.1993) (although CSAAS is not yet generally accepted and thus not admissible to prove sexual abuse actually occurred, expert testimony based on experience, observation, and literature may be admitted to explain behavior of alleged victim, including delayed reporting); cf. Lantrip v. Kentucky, 713 S.W.2d 816 (Ky.1986) (an example of cases holding CSAAS not generally accepted, therefore testimony inadmissible); see also Isely v.

Capuchin Province, 877 F.Supp. 1055 (E.D.Mich.1995) (evidence such as Dr. van der Kolk’s admissible, but expert may not testify about victim’s credibility). ¶26 We have reached similar conclusions in rape eases.

In upholding a rape conviction based in part on psychiatric testimony regarding the way in which post-traumatic stress syndrome might have affected the victim’s behavior, we noted that courts in other states disagreed on the admissibility of so-called rape trauma syndrome to prove the rape occurred but nevertheless concluded: Although we might have some difficulty in upholding the admissibility of rape trauma syndrome to prove the existence of a rape, we believe, however, if properly presented by a person qualified by training and experience such as a psychiatrist or psychologist, that such evidence is admissible to show lack of consent.

This testimony would not invade the province of the jury. The expert would be subject to cross-examination and the jury could then determine what weight the evidence is to receive. State v. Huey, 145 Ariz. 59, 63, 699 P.2d 1290, 1294 (1985). ¶ 27 Other states have reached similar conclusions with regard to rape trauma syndrome. The California Supreme Court, for example, applied Frye and concluded that expert testimony was not admissible to prove that rape occurred.

If factually relevant, however, it would have been admissible to explain behavior following the incident and to rebut popular misconceptions that might have given credence to a defendant’s argument that the victim’s delayed reporting or other behavior would justify an inference that rape had not occurred. California v. Bledsoe, 36 Cal.3d 236, 203 Cal.Rptr. 450, 681 P.2d 291, 298-99 (1984); see also Colorado v.

Hampton, 746 P.2d 947, 949-52 (Colo.1987) (collecting eases and holding that Frye test inapplicable when behavioral testimony offered to explain ninety-day reporting delay). ¶28 These principles are not limited to criminal cases. The same rationale is applied in cases involving medical causation and techniques. Gilkey v. Schweitzer, 295 Mont. 345, 983 P.2d 869 (1999) (evidentiary standards applicable to novel scientific evidence should not have been applied to preclude anesthesiologist’s expert opinion that placement of catheter while patient was anesthetized increased risk of injury).

In a recent case in which the operative facts are quite similar to those in this case, the court was required to decide whether a physician’s testimony based on experience, observation, and study of literature was admissible on the question of whether stress could trigger otherwise asymptomatic multiple sclerosis. Colwell v. Mentzer Inv., Inc., 973 P.2d 631 (Colo.App.1998). Refusing to apply Frye and using a version of Rule 702 identical to Arizona’s, the court blended a number of theories but held the testimony should be admitted.

The admissibility of such testimony should be determined by balancing (1) the reliability of the scientific principles upon which the testimony rests, i.e., the potential to aid the jury in reaching an accurate resolution of a disputed issue, and (2) the likelihood that the introduction of the evidence may overwhelm or mislead the jury.

The reliability inquiry does not require a process of scientific “nose-counting.” Rather, a court should consider factors such as the degree of acceptance in the scientific community, the novelty of the scientific principle, and the existence of specialized literature on the subject. The expert’s qualifications and expertise in the area of MS were not disputed, and the trial court determined that his testimony would be helpful to the trier of fact. His testimony did not involve the application of any novel or newly developed scientific device or process, nor did it involve the manipulation of physical evidence.

Rather, it concerned his observations of thousands of cases of MS and review of studies by others. Plaintiffs expert, a board certified neurologist, testified that he has been in practice for over 40 years. At the time of the trial he taught at Harvard Medical School and ran the multiple sclerosis project at the Beth Israel Hospital in Boston, Massachusetts. He testified that over the course of his career he had seen between 5,000 and 6,000 MS patients.

In his opinion, certain kinds of stress in some patients with MS can trigger the appearance of symptoms in an asymptomatic patient____ The evidence presented at trial concerned the effect that stress could have in causing MS to become symptomatic. Such testimony would assist the trier of fact in understanding the evidence of what researchers in the field have discovered. Thus, the evidence satisfies the threshold inquiry. Id. at 636-37 (citations omitted). ¶29 Finally, a recent California case directly on point puts the matter quite well.

The plaintiffs claimed their memory of sexual abuse by their father and stepfather had been repressed and then fortuitously triggered. They offered expert evidence by a psychologist who specialized in the field of sexual abuse and memory. The California court refused to apply either Frye or Dau-bert and affirmed the trial judge’s refusal to hold a Frye hearing, holding the judge correctly admitted the expert’s opinion that the circumstances and plaintiffs’ behavior were “consistent with other individuals who had repressed their memories of childhood sexual abuse.” Wilson v.

Phillips, 73 Cal.App.4th 250, 86 Cal.Rptr.2d 204, 206 (1999). The court explained: California distinguishes between expert medical opinion and scientific evidence; the former is not subject to the special admissibility rule of Kelly-Frye. Kelly-Frye applies to cases involving novel devices or processes, not to expert medical testimony, such as a psychiatrist’s prediction of future dangerousness or a diagnosis of mental illness. Similarly, the testimony of a psychologist who assesses whether a criminal defendant displays signs of deviance or abnormality is not subject to Kelly-Frye.

Id. at 207 (quoting California v. Ward, 71 Cal.App.4th 368, 83 Cal.Rptr.2d 828, 833 (1999) (Frye inapplicable- to psychologist’s opinion of defendant’s propensity to repeat sexually violent behavior)). The Martone dissent labels Wilson a “renegade” case. Martone dissent at ¶ 81. In fact, it is simply the latest in a long line of California cases refusing to apply Frye to testimony like that offered from Doctor van der Kolk.

See Wilson, 86 Cal.Rptr.2d at 206-08 (citing cases). ¶ 30 There are many more cases, with varying rationales and conclusions, but we extract and apply the same rule that our courts have previously applied in cases involving Ariz.R.Evid. 702. See, e.g., Huey, 145 Ariz. 59, 699 P.2d 1290; Lindsey, 149 Ariz. 472, 720 P.2d 73; and Moran, 151 Ariz. 378, 728 P.2d 248.

Opinion testimony on human behavior is admissible when relevant to an issue in the case, when such testimony will aid in understanding evidence outside the experience or knowledge of the average juror, and when the witness is qualified, as Ariz.R.Evid. 702 requires, by “knowledge, skill, experience, training, or education.” To put it simply, Frye is inapplicable when a qualified witness offers relevant testimony or conclusions based on experience and observation about human behavior for the purpose of explaining that behavior.

Of course, orn-eases forbid a witness from expressing an opinion on the alleged victim’s credibility or the truth of allegations of sexual abuse or rape. This principle applies as well in the present case to Doctor van der Kolk’s proposed testimony. Expert testimony is admitted to explain behavior that a party claims is consistent or inconsistent with the alleged event.

As we said in Hummert: Although compliance with Frye is necessary when the scientist reaches a conclusion by applying a scientific theory or process based on the work or discovery of others, under Rules 702 and 703 experts may testify concerning their own experimentation and observation and opinions based on their own work without first showing general acceptance. Such evidence need only meet the traditional requirements of relevance and avoid substantial prejudice, confusion, or waste of time. 188 Ariz. at 127, 933 P.2d at 1195; see also California v.

McDonald, 37 Cal.3d 351, 208 Cal.Rptr. 236, 690 P.2d 709 (1984). ¶ 31 This does not mean, as the dissenters argue, that we believe the practice of medicine, including psychiatry, is not based on science. See Martone dissent at ¶¶ 79, 87-88; McGregor dissent at ¶ 102. Rather, it means that expert evidence based on a qualified witness’ own experience, observation, and study is treated differently from opinion evidence based on novel scientific principles advanced by others. As in the past, Frye continues to apply only to the latter.

The June 11 Order applied Frye to prohibit observation- and experience-based expert testimony about recovered memory, no matter for what purpose offered. Insofar as it relied on Frye, the order was therefore overbroad and legally erroneous and must be vacated. See State v. Chapple, 135 Ariz. 281, 297 n. 18, 660 P.2d 1208, 1224 n. 18 (1983).

Because the evidence in question is not precluded by the Frye test, its admissibility is to be determined under Ariz.R.Evid. 702. ¶ 32 The Martone dissent misstates and exaggerates our holding by propheeying that our refusal to apply Frye to Doctor van der Kolk’s testimony means that “any expert” on human behavior can hereafter be allowed to testify to any theory, “however farfetched,” without any showing of scientific reliability. Martone dissent at ¶¶ 80-81. Doctor van der Kolk is not any expert testifying to farfetched theories.

As one glance at his curriculum vitae shows, he is a very experienced, well recognized, respected clinician with degrees in psychology and medicine. See Appendix A. He is asked to testify to his experience and observation in caring for patients, such as Plaintiff, who report repressed memory of sexual abuse. We hold simply that he can be asked to testify to his opinions based on the results of his experience, his observations, his own research and that of others with which he is familiar, and the care of his patients.

It is true that some or many research psychologists, including Defendant’s witness, disagree, mainly because repressed memory is “woefully short” of empirical verification. See 1 David L. Faigman, David H. Kaye, Michael J. Saks, & Joseph Sanders, Modern Scientific Evidence: The Law and Science of Expert Testimony § 13-1.5, at 534 (1997). But as the succeeding paragraph of the cited treatise points out, we must “also balance justice, fairness, efficiency, and other factors related to [the law’s] special role in American society.” Id, at 535.

In doing so, we must decide whether the judge or the jury should resolve the controversy between clinical psychiatrists and psychologists on the one hand and research psychologists on the other. This, of course, brings us back again to the application of Rule 702 and Daubert as interpreted by the cases that follow it. D. Rule 702 and Daubert ¶ 33 One method of interpreting Rule 702 of the Federal Rules of Evidence is that adopted by the United States Supreme Court in Daubert.

It was unclear at first whether Daubert applied only to the methodology used to reach scientific opinions or whether it applied to all opinion evidence offered under Rule 702. The Court subsequently held that a district judge’s reliability determination applied to both conclusions and methodology and was reviewable only on an abuse of discretion standard. General Electric Co. v. Joiner, 522 U.S. 136, 141, 118 S.Ct. 512, 517, 139 L.Ed.2d 508 (1997). Then in Kumho Tire Co., Ltd. v.

Carmichael, the Court applied Daubert’s gatekeeper concept to the testimony of a tire failure expert, explaining that the Daubert rule was applicable to all opinion evidence offered under Fed.R.Evid. 702. 526 U.S. 137, 147-51, 119 S.Ct. 1167, 1174-75,143 L.Ed.2d 238 (1999). ¶ 34 One treatise has summarized the effect of these three cases in the following words: The Kumho Court explained that the language of Rule 702 makes no relevant distinction between “scientific” knowledge and “technical” or “other specialized knowledge.” Moreover, such a distinction would be hard to draw, since there is no clear line that divides scientific from other types of expert knowledge.

Proposed amendments to Rule 702 also address the applicability of the Daubert principles. The Advisory Committee Note to the proposed amended rule states that expert testimony of all types presents questions of admissibility for the trial court in deciding whether the evidence is reliable and helpful. The proposed amendment would provide that all expert testimony must be based on reliable facts or data and be the product of reliable principles and methods, and requires the witness to have applied the principles and methods reliably to the facts of the case. Jack B. Weinstein & Margaret A.

Berger, 4 Weinstein’s Federal Evidence § 702.05[2][b] (Joseph M. McLaughlin, ed., 2d ed.1997) (footnotes omitted). The reliability requirement is designed to exclude so-called “junk science” — conjuring up memories of the phrenology craze where the bumps on a person’s head were felt in order to determine character traits — from federal courts. At the very least, scientific opinions offered under Rule 702 must be based on sound scientific methods and valid procedures. The primary focus must be on the principles and methods used, not on the conclusions generated.

But conclusions’ and methodology are “not entirely distinct from one another.” District courts are not required to admit “opinion evidence which is connected to existing data only by the ipse dixit of the expert. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered.” Id. § 702.05[3] (footnotes omitted). ¶ 35 Both parties urge that this court adopt the Daubert

interpretation of Ariz. R. Evid. 702. Plaintiff urges that the record as it stands is sufficient to require admission of Doctor van der Kolk’s testimony, while Defendant argues that the present record permits us to affirm the trial judge’s preclusion ruling under Daubert or at least to remand so that the trial judge can reconsider his ruling under Daubert and its progeny. ¶ 36 In Daubert, the Court noted that Frye preceded adoption of the Rules of Evidence and concluded that those rules had been designed to liberalize the use and admission of opinion evidence. 509 U.S. at 587, 113 S. Ct. at 2794.

The result reached in Kumho, however, would seem directly opposed to the principle of liberalized admissibility that engendered the abolition of Frye. Michael N. Graham, The Daubert Dilemma — At Last A Viable Solution, 179 F.R.D. 1, 6 (1998) (criticizing Daubert and urging states to adhere to Frye). ¶ 37 Arizona adopted Frye in 1962. See State v. Valdez, 91 Ariz. 274, 371 P.2d 894 (1962) (precluding polygraph evidence for its failure to gain general acceptance). We adopted our version of the Rules of Evidence in 1977.

Many courts and commentators believed that Frye “could be read into the regulation of expert testimony in Rule 702.” 22 Charles Alan Wright & 'Kenneth W. Graham, Federal Practice and Procedure § 5168.1, at 85 (Supp.1998); see also McCormick on Evidence § 203, at 731 (John W. Strong, ed., 5th ed.1999). Unlike the United States Supreme Court, however, we have left no. doubt whether Ariz.R.Evid. 702 was intended to abolish the Frye doctrine, for we have continued to apply Frye since the adoption of Rule 702 and have faced these same questions before. ¶ 38 In State v.

Bible, we were asked to abandon Frye, adopt Daubert, and admit DNA statistical probability evidence. We held the statistical evidence inadmissible under Frye, pointing out that Daubert was a departure from Ariz.R.Evid. 702, that the “nature of [its] requirement is currently unknown, may vary from case to case and is to be fashioned by trial judges using an analytical framework as yet unspecified, ... leavpng] many questions unanswered.” 175 Ariz. 549, 580, 858 P.2d 1152, 1183 (1993). Recognizing the shortcomings in the Frye rule, we nevertheless decided to postpone deciding whether to adopt Daubert. Id.

Presented with the same question in a later ease, we came to the same conclusion: the “federal courts have not yet had a fair opportunity to apply Daubert; thus it is too early to properly evaluate it.” State v. Johnson, 186 Ariz. 329, 331, 922 P.2d 294, 296 (1996). But Joiner and Kumho now flesh out Daubert’s bare bones, the parties in the present case have argued the issue, and we must therefore address it to give our trial courts direction on the issues before them. ¶ 39 Daubert and its progeny have not been received with unanimous approbation.

The dissenters speak of Daubert as if it worked only a small change, if any, in the law for it only requires the trial judge to perform the ordinary “legal task of determining both the relevance and the reliability of scientific foundation.” Martone dissent at ¶ 91; McGregor dissent at 11103. But Daubert’s “shift in perspective is subtle yet profound. Whereas Frye required judges to survey the pertinent field to assess the validity of the proffered scientific evidence, Daubert calls upon judges to assess the merits of the scientific research supporting an expert’s opinion.” 1 Faigman, et al., supra, at viii.

Thus, leading commentators and authorities in the field of evidence have criticized it. See, e.g., 29 Charles Alan Wright & Victor J. Gold, Federal Practice and Procedure § 6266, at 266 n. 15 (Supp.1998) (“Any relevant conelu-sions supported by a qualified expert witness should be received unless there are distinct reasons for exclusion. These are the familiar ones” already contained in the rules.) (citations omitted). Professor Wright’s criticism is thought-provoking: Additionally, the Daubert opinion offers no convincing rationale for a special test for the admissibility of expert scientific testimony.

Many writers have thought that it was enough to abolish Frye and leave the supposed problems of “junk science” to the normal rules of relevance. While the Court’s opinion does suggest that the adversary system is better than exclusion as a method of dealing with neo-phrenologists, the opinion also suggests that motions for

summary judgment or directed verdicts may be employed by judges who don’t trust jurors to treat anti-corporate science with the appropriate disdain. Since those remedies are only effective against those who bear the burden of proof, this suggests that the Court supposes that the persons most deserving of special protection from spurious expertise are corporations and other wealthy defendants — the very parties most capable of manufacturing or purchasing questionable scientific opinions.

Finally, the Daubert opinion appears politically naive about the “methods and procedures” of both science and evidentiary admissibility. As to the first, students of science have commented on the fact that peer review and other techniques of scientific validation suffer from a lack of political sophistication. This is a serious flaw in relying on those methods to determine evidentiary admissibility because this politicized science is prevalent in litigation. The Daubert case is itself a good example.

Whether or not Benedictin is capable of causing cancer may be a scientific question but it is one of a different order from whether birds are descended from dinosaurs or the Big Bang theory is “true.” Broad questions, such as whether AIDS is caused by the HIV virus, are likely to benefit from the scientific “adversary system”; narrower questions, such as the efficacy of the Daikon shield, are of less general interest and thus escape more rigorous scientific scrutiny. Similarly, the Daubert opinion seems naive about the politics of procedure.

Multi-factored, “flexible” tests of the sort announced in Daubert are more likely to produce arbitrary results than they are to produce nuaneed treatment of complex questions of admissibility. All the Court would have had to do to appreciate this was to look at the history of Evidence Rule 403. Similarly, the Court’s suggestion that questions of the validity of scientific evidence be handled by motions for

summary judgment or directed verdicts may be read as an invitation to kill off disfavored causes of action in comparative secrecy rather than assassinate them by evi-dentiary rulings in open court. 22 Wright & Graham, supra § 5168.1, at 86-87 (emphasis added). ¶ 40 While Professor Wright’s supplement was written before Kumho, that case significantly heightens the problems. In Kumho, the Court held the district judge properly acted as a reliability gatekeeper in finding insufficient indications of the reliability of the methodology used by a tire failure expert.

The judge has broad discretion, the Court said, to determine and apply standards of reliability on a case-by-case basis. 526 U.S. at 149-53,119 S.Ct. at 1175-76. With all due respect, the argument that follows and affirms the trial judge’s unreliability finding reads more like a jury argument than an application of legal principle. Id. at 151-59, 119 S.Ct. at 1176-79. ¶41 It is impossible, indeed, to reconcile Kumho with the Court’s earlier decision in Barefoot v.

Estelle, a capital case in which the prosecution presented psychiatric opinion evidence predicting the possibility of the defendant’s future dangerousness if not sentenced to death. 463 U.S. 880, 103 S.Ct. 3383, 77 L.Ed.2d 1090 (1983).

Rejecting the position of the amicus, the American Psychiatric Association, that psychiatrists “are incompetent to predict [such future behavior] with any acceptable degree of reliability,” the Court said: In the second place, the rules of evidence generally extant at the federal and state levels anticipate that relevant, unprivileged evidence should be admitted and its weight left to the factfinder, who would have the benefit of cross-examination and contrary evidence by the opposing party.

Psychiatric testimony predicting dangerousness may be countered not only as erroneous in a particular case but also as generally so unreliable that it should be ignored. If the jury may make up its mind about future dangerousness unaided by psychiatric testimony, jurors should not be barred from hearing the views of the State’s psychiatrists along with opposing views of the defendant’s doctors. Id. at 898, 103 S.Ct. at 3397.

The Court was confident “that the factfinder and the adversary system” would be “competent to uncover, recognize and take due account of [the] shortcomings” of possibly unreliable expert opinion. Id. at 899,103 S.Ct. at 3398. ¶42 Daubert does not mention Barefoot. Perhaps the Court intends to interpret Fed. R.Evid. 702 differently in criminal cases. But as the earlier survey of our cases shows, in criminal prosecutions we have not subjected testimony seeking to explain human behavior to any preliminary gatekeeping test of reliability.

We do not believe different tests should apply in civil cases; to the contrary, rules determining the competency of evidence should apply across the board, whether the case is on the civil or criminal calendar. We find it hard to believe that evidence deemed admissible in prosecutions resulting in imposition of death or long terms of imprisonment should be held unreliable and therefore inadmissible in tort cases based on the same type of act that leads to many criminal prosecutions. ¶ 43 Perhaps the Court had reason to see things differently in the ten years that elapsed between Barefoot and Kumho.

Nothing in Daubert or Kumho indicates this, but perhaps history permits us to “identif[y] the unarticulated reasons that [may] explain this erratic journey.” Michael H. Gottes-man, From Barefoot to Daubert to Joiner: Triple Play or Double Error?, 40 Ariz. L.Rev. 753, 753 (1998). Professor Gottes-man’s

article traces the unhappiness of some federal appellate judges with what they perceived-as the “phenomenon of venal experts saying anything the parties paying their fees wanted.” Id. at 756, 119 S.Ct. 1167. He mentions also Judge Posner’s comments, in a similar vein, in Chaulk by Murphy v. Volkswagen of America, Inc., 808 F.2d 639, 644 (7th Cir.1986) (Posner, J., dissenting), and Peter Huber’s book, Galileo’s Revenge: Junk Science in the Courtroom (1991), both advocating a judicial reliability screen.

Then, in 1991 there was an effort by the Civil Rules Advisory Committee to change- the Federal Rules of Evidence to incorporate such a screen. Gottesman, supra, 40 Ariz. L.Rev. at 757. The proposal was first withdrawn, then resubmitted with the backing of the Bush administration and Solicitor General Starr, who acknowledged that the Federal Rules of Evidence were not intended to and did not provide for such a screen. See Dan Quayle, Agenda for Civil Justice Reform in America, 60 U.Cinn.L.Rev. 979, 999 (1992); see also Paul C.

Giannelli, Daubert: Interpreting the Federal Rules of Evidence, 15 Cardozo L.Rev.1999, 2017 (1994). ¶44 One problem with this agenda for reform was that the Federal Rules of Evidence were enacted by Congress. Act of January 2, 1975, Pub. Law 93-595, 88 Stat. 1926; Giannelli, supra, 15 Cardozo L.Rev. at 2003. See a description of the general rule-making process in Beech Aircraft Corp. v. Rainey, 488 U.S. 153, 163-65, 109 S.Ct. 439, 447-48, 102 L.Ed.2d 445 (1988), which also comments on the rules’ “general approach” of “relaxing the traditional barriers to opinion testimony.” Id. at 169, 109 S.Ct. at 450.

Thus, any modification of Fed.R.Evid. 702 and 703 could be accomplished only through congressional action on whatever recommendation might come from the rules committee. Gottesman, supra, 40 Ariz.L.Rev. at 757.

It was at this stage that the Supreme Court mooted the issue in 1993 with Daubert’s holding that the existing rule incorporated a reliability screen, authorizing the trial judge to determine reliability (and eventually, in Kumho, essential credibility) of a qualified expert’s testimony as a prerequisite for the jury’s determination of the same issues. ¶45 In erecting this hurdle for opinion evidence, the Court found a reliability standard inherent in the 1972 formulation of Fed.

R.Evid. 702, although neither the federal rules committee nor the congressional judiciary committees even discussed such a standard or the Frye issue. Giannelli, supra, 15 Cardozo L.Rev. at 2000-01. Nor had such a standard been considered in prior efforts at evidentiary codification, such as the Uniform Rules of Evidence and the Model Code of Evidence. Id. at 2017. The issue of scientific reliability as a prerequisite for admission of scientific evidence actually arose in the 1991 recommendations of the Civil Rules Advisory Committee.

Id.; Gottesman, supra, 40 Ariz.L.Rev. at 757. ¶46 Turning to our rules, nothing in the comments of this court or its committees indicated that a reliability standard was contemplated by our adoption of Ariz.R.Evid. 702.

Given the rule’s text and cases such as Hummert, 188 Ariz. 119, 933 P.2d 1187; Johnson, 186 Ariz. 329, 922 P.2d 294; and Bible, 175 Ariz. 549, 858 P.2d 1152 — all decided after we adopted Ariz.R.Evid. 702 — we could not now discover such a standard implicit in the language of the rule, phrased as it is in terms of “specialized knowledge” that will assist the jury “to understand the evidence or to determine” the facts and permitting expert testimony when a witness is “qualified ... by knowledge, skill, experience, training, or education.” Nor do we believe we should interpret the rule to include such a standard. ¶47 There are a number of reasons for this.

First, our experience with the Frye rule has not been bad. It is true, as the Supreme Court indicated in Daubert and the commentators note, Fed.R.Evid. 702 did not purport to adopt the Frye principle. Dau-bert, 509 U.S. at 588, 113 S.Ct. at 2794. See ¶ 37, supra. But the rules did contemplate “further common law development,” which would not, of course, exclude the “vitality of the general acceptance standard” for certain types of testimony. McCormick on Evidence § 203, at 731.

Review of our cases leads us to conclude that our formulation of the Frye rule, limiting it, as we have in our case law, to a witness’ opinion based on application of novel scientific principle or technique formulated by another, has been strict enough to enable our trial judges to reject the truly questionable while enabling them to admit those principles and techniques based on generally accepted scientific theory. And our trial and appellate judges have been commendably able in making prompt and accurate Frye determinations in even the most difficult and arcane disciplines.

Thus, although we recognize that Frye is not perfect, we believe it is a necessary and generally helpful rule. Bible, 175 Ariz. at 578-80, 858 P.2d at 1181-83. We have not yet seen any reason to conclude that the rule, as limited and applied in our ease law, needs liberalizing; nor, as explained in

section C supra, do we believe its application should be broadened to apply to behavioral or experience-based testimony.

To change the law in that manner would call into question a large number of criminal convictions or at least raise profound questions of why a rule good enough for criminal cases carrying draconian penalties is not good enough for what Justice Blackmun described in Barefoot as “routine lawsuits for money damages.” See note 5, supra. ¶48 One of the arguments for adopting Daubert is to allow trial judges to put a halt to improper verdicts from jurors misled by junk science and experts ready at the drop of a'hat (or a dollar) to say anything for any party.

This, of course, is a two-edged sword — plaintiffs’ lawyers do not have a monopoly on venal or inaccurate experts. But we do not believe Daubert/Kumho will prove to be a perfect or even a good antidote. Implicit in Joiner and Kumho is the assumption that trial judges as a group will be more able than jurors to tell good science from junk, true scientists from charlatans, truthful experts from liars, and venal from objective experts.

But most judges, like most jurors, have little or no technical training “and are not known for expertise in science,” let alone in the precise discipline involved in a particular case. 1 Faigman, et al., supra, at vii. ¶ 49 Nor do our trial judges have time for Kumho hearings in each case in which expert testimony is to be offered. Those hearings require the equivalent of a Frye hearing, for general acceptance is one of the Daubert factors, and also require findings in a variety of other matters, changing from case to case. Kumho, 526 U.S. at 149-53, 119 S.Ct. at 1175-76.

As Judge Kozinski noted, applying Daubert will be a “complex and daunting task.” Daubert v. Merrell Dow Pharmaceuticals, 43 F.3d 1311, 1316 (9th Cir.1995). The dissenters have an optimistic view of Daubert and Kumho, but that view is quite premature. See Martone dissent at ¶ 90-92; McGregor dissent at ¶ 104.

The co-author of what the Martone dissent describes as the “preeminent treatise” on scientific evidence acknowledges that it will take at least the “next several years [to] determine whether Daubert was an enlightened step forward in the way the law uses science or a stumble backward into the darkness of a ‘Kafkaesque nightmare.’ ” David L. Faigman, Legal Alchemy 61 (1999). ¶ 50 The present case, with its proliferation of paper, is the paradigm of the problem Kumho would present. Unlike Frye, Kumho applies to all cases involving expert testimony, not just those involving a specific novel scientific principle.

Further, while a Frye order establishes general acceptance of a theory for all cases, under Daubert/Kumho each trial judge in any case involving disputed expert testimony would have to review the eight or nine Daubert/Kumho factors so far revealed to us in ease-specific pretrial testimonial hearings to determine reliability of the expert’s techniques, experience, observation, methodology, and conclusions — subjectively inquiring into and determining not only general acceptance but all the factors so far identified and any others that appellate courts may yet deem appropriate to save us from juries that have been led or misled down the garden path.

See Joseph T. Walsh, Keeping the Gate, 83 Judicature 140, 143 (1999). Of course, no one can quantify how many times juries have been fooled by junk science, though it undoubtedly has occurred, or how many times this has favored the prosecution or the defense, the plaintiff or the defendant.

Nor can anyone say how much more or truer justice would have been or will be attained if judges get the first crack at the evidence, together with the hitherto unprecedented power to preclude the jury from hearing contested, relevant evidence from a qualified witness. ¶ 51 But let us assume, as does Justice Martone, that given the power conferred by Kumho, our trial judges would do better than juries. See Martone dissent at ¶¶ 93-94. Even then we would not follow Daubert as interpreted in Kumho.

Our constitution preserves the “right to have the jury pass upon questions of fact by determining the credibility of witnesses and the weight of conflicting evidence.” Burton v. Valentine, 60 Ariz. 518, 529, 141 P.2d 847, 851 (1943). The framers’ intent does not contemplate giving judges the power to determine reliability and credibility of a qualified expert as a prerequisite to submission of the expert’s conclusions to a jury for its determination of the weight to be given to the testimony.

One other feature of the constitution might fairly be described as a device to allow for direct popular control of governmental action — the right of trial by jury. Consistent with their overall philosophy, the Arizona framers not only provided that the right shall “remain inviolate” (Article II,

section 23) but took further steps to guard against encroachments on the independence of juries. Judges were forbidden to charge juries with respect to “matters of fact” and were prohibited from commenting on the evidence (Article VI,

section 27). In the case of lawsuits to recover damages for death or injury, defenses of assumption of risk and contributory negligence were “in all cases whatsoever [and] at all times, [to] be left to the jury” (Article XVIII,

section 5). John D. Leshy, The Arizona State Constitution, A Reference Guide 12 (1993). It would be strange that a judge forbidden to comment on the reliability or credibility of testimony would be empowered to preclude the jury from hearing the testimony at all because the judge believes it to be unreliable or not worthy of belief. Reduction or obliteration of the jury function may be seen by some as the ultimate tort reform, but it is one prohibited by our organic law. ¶ 52 We believe Joiner and Kumho approach that result.

The judge is made the gatekeeper, empowered to make preliminary determinations of reliability and credibility of qualified witnesses and to exclude the testimony of such witnesses if the judge concludes there is not a “valid connection” between the testimony and the “pertinent inquiry.” Kumho, 526 U.S. at 149, 119 S.Ct. at 1175. Judges, of course, have the responsibility to exclude irrelevant evidence, but the valid connection to which Kumho refers goes far beyond determining relevancy.

It includes the judge’s determination of the “testimony’s factual basis, data, principles, methods, or their application” to ascertain “whether the testimony has ‘a reliable basis in the knowledge and experience of [the relevant] discipline.’ ” Id. (quoting Daubert, 509 U.S. at 592, 113 S.Ct. at 2786). Questions about the accuracy and reliability of a witness’ factual basis, data, and methods go to the weight and credibility of the witness’ testimony and are questions of fact. The right to jury trial does not turn on the judge’s preliminary assessment of testimonial reliability.

It is the jury’s function to determine accuracy, weight, or credibility. ¶ 53 Arizona’s constitutional right to a jury trial does not, of course, forbid the trial judge from ruling on admission of evidence. The judge may certainly do so, and when the testimony is based on a novel scientific principle that the witness has taken from others and applied to the case at hand, the judge may, as a matter of foundation, require a showing of general acceptance.

The Daubert/Joiner/Kumho trilogy of cases, however, puts the judge in the position of passing on the weight or credibility of the expert’s testimony, something we believe crosses the line between the legal task of ruling on the foundation and relevance of evidence and the ■jury’s function of whom to believe and why, whose testimony to accept, and on what basis. Kumho’s rationale illustrates the point. For example: [S]ome of Daubert’s questions can help to evaluate the reliability even of experience-based testimony.

In certain cases, it will be appropriate for the trial judge to ask, for example, how often an engineering expert’s experience-based methodology has produced erroneous results, or whether such a method is generally accepted in the relevant engineering community. Likewise, it will at times be useful to ask even of a witness whose expertise is based purely on experience, say, a perfume tester able to distinguish among 140 odors at a sniff, whether his preparation is of a kind that others in the field would recognize as acceptable. 526 U.S. at 151, 119 S.Ct. at 1176.

Such undoubtedly pertinent questions are better left to counsel, and the authority to decide them constitutionally left to jurors. We have no doubt that jurors will be as able as judges, if not more so, to evaluate the testimony of the perfume sniffer who prepares by a method unacceptable to most testers. ¶ 54 This opinion does not lessen the trial judge’s authority to determine the admissibility of evidence. See Ariz.R.Evid. 104(

a) and (b). Rule 702 conditions admission of opinion evidence in part on the judge’s determination that the evidence will “assist the trier of fact to understand the evidence or to determine a fact in issue.” This, of course, pertains to the nature of the subject on which the opinion is to be given rather than the credibility of the witness expressing the opinion. Lindsey, 149 Ariz. at 495, 720 P.2d at 96; see also Cynthia H. Cwik, Guarding the Gate: Expert Witness Admissibility, 25 Litigation 6 (1999).

Kumho elevates the concept of assistance to impermissible heights by allowing the trial judge to reject opinion testimony based on his or her views about the reliability and accuracy of the data relied on, the credibility of the witness, or the weight that should be given that witness’ testimony. Of course, the line is difficult to draw, but in this ease the judge’s ruling on admissibility crossed the line and intruded on the jury’s function. ¶ 55 We do not lessen trial judges’ authority.

We do not reject Kumho on a constitutional basis but because the authority over the admission of evidence given to trial judges by Kumho is much different from the authority long recognized by the Federal Rules of Evidence and the common law of evidence. Daubert and Kumho give the judge authority to preclude evidence because the judge disagrees with the methodology used by the witness or believes the methodology is unreliable or the witness is less credible than the witness produced by the other side. Kumho, in other words, permits the judge to engage in the weighing factor.

Neither the common law of evidence nor the Federal Rules of Evidence permitted this type of judicial activism. The trial judge had authority to exclude evidence when it violated some rule of law, such as the best evidence rule or the hearsay rule. See Richard O. Lempert, The Jury and Scientific Evidence, IX Kan. J.L. & Pub. Pol’y 22 (1999). The trial judge was empowered to weigh and make judgments whether otherwise admissible evidence was to be excluded because its prejudicial value outweighed its probative value.

But until Kumho, nothing in the rules or the common law permitted the judge to exclude evidence based on his or her conclusions as to the credibility of a qualified witness’ conclusions. ¶ 56 We thus conclude that we should not and cannot adopt the Joiner and Kumho

interpretation of Daubert but will continue to apply Ariz.R.Evid. 702 as written. Our conclusion is not, as the Martone dissent suggests, based on a lack of confidence in or appreciation for trial judges but instead an appreciation for the different functions of the trial judge and the jury. Justice McGregor’s dissent points out that there are only seventeen states that have not adopted Daubert and expresses concern that we are overreacting to Kumho so that today’s decision will possibly isolate Arizona from the “mainstream of judicial analysis.” McGregor dissent at ¶ 99.

These are matters of concern, but we believe we adopt the better rule and that in the long run the dangers of Kumho will be perceived and the mainstream of judicial decision will either shift or Kumho’s reach will be confined and Daubert applied as it should be — to questions of novel scientific evidence. ¶ 57 Our holding does not open the doors of our courthouses to false science and charlatans. The Frye rule remains as a barrier to offers of novel scientific and possibly pseudoscientific theory.

The Rules of Evidence, and Rule 702 itself, erect barriers to admission of all opinion evidence: the evidence must be relevant, the witness must be qualified, and the evidence must be the kind that will assist the jury. See Washington v. Greene, 139 Wash.2d 64, 984 P.2d 1024,1028-30 (1999) (even though Frye was satisfied and witness qualified, testimony on multiple personality-dissociative identity disorder properly excluded in criminal prosecution because diagnosis was incapable of forensic application to Washington’s

definitions of legal insanity or diminished capacity; evidence therefore would not have assisted jury in performing its function); see also Oregon v.

Brown, 297 Or. 404, 687 P.2d 751 (1984) (abandoning Frye rule, Oregon Supreme Court holds expert opinion evidence admissible under traditional standards of relevancy, and factors identified in Rule 702 — qualified witness and testimony assisting jury; latter factors satisfied if testimony is within witness’ field, witness is qualified, and opinion foundation intelligibly relates testimony to facts; even so, exclusion still possible under Rule 403). ¶ 58 As Brown points out, the rules also permit trial judges to reject even relevant evidence that meets the Rule 702 test if the probative value is “substantially outweighed by the danger of unfair prejudice, confusion ... or misleading the jury, or by considerations of undue delay, waste of time----” Ariz.R.Evid. 403.

One could thus hypothesize that trial judges would not exceed their authority in excluding evidence based on theories of the Flat Earth Society, the Aristotelian concept of cosmology, astrology, or other false or pseudoscience. But our system provides even better tools to save us from junk scientists and charlatans. As the Supreme Court itself acknowledged, “vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.” Daubert, 509 U.S. at 596, 113 S.Ct. at 2798.

For those who truly believe in the jury system, this, although imperfect, should be enough. ¶ 59 Thus, we address the problems inherent in false opinion evidence without permitting trial judges to encroach on the province and independence of the jury under the guise of acting as gatekeepers. We have armed trial judges with the ability to take the case from the jury even when there is a bare scintilla of evidence to support the claim. Orme School v. Reeves, 166 Ariz. 301, 802 P.2d 1000 (1990). But it is one thing to permit trial judges to grant

summary judgment or direct a verdict when there is no more than a scintilla of evidence supporting a claim and a wholly different thing to give them the power to reduce the evidence to a scintilla by excluding otherwise admissible testimony from qualified witnesses simply because they disagree with the opinion’s basis or believe the expert untrustworthy or unreliable. ¶ 60 Finally, there, are other solutions available if a judge believes there is a substantial possibility that a jury might be misled or fooled by plausible but very untrustworthy testimony from a dubious expert witness.

Rule 706, Ariz.R.Evid., for instance, permits a judge in such an extraordinary situation to appoint an expert and sets forth the procedure to be followed. See also McCormick on Evidence § 203, at 733-34. ¶ 61 We therefore reject the Joiner and Kumho

interpretations of Rule 702. In doing so, we do not close the door to continuing common-law evolution or refinement of either Frye or Rule 702 and will continue to be responsive and receptive to evolving methods of addressing any abuses in the use of expert testimony. See, e.g., Rule 26(b)(4)(D), Arizona Rules of Civil Procedure (limiting number of expert witnesses); Rule 1(D)(4), Arizona Uniform Rules of Practice for Medical Malpractice Cases (same).

SUMMARY AND CONCLUSION ¶ 62 It is no doubt tempting, but potentially quite harmful, to exaggerate the breadth and scope of this decision to support erroneous predictions of the dire consequences that will follow. See Martone dissent at ¶¶ 79-81. To compare the repressed memory controversy between clinical psychiatrists and psychologists on the one hand and research psychologists on the other to a debate over astrology is, to put it tactfully, quite a stretch. So is the fear that “any expert” can testify to any conclusion, no matter how scientifically unreliable.

Our decision, like Kumho, does not turn on an attempt to determine whether repressed memory is “scientific” or “unscientific.’’ Plaintiff does not claim her memories are proved true as a matter of scientific fact. Frye is applicable when an expert witness reaches a conclusion by deduction from the application of novel scientific principles, formulae, or procedures developed by others. It is inapplicable when a witness reaches a conclusion by inductive reasoning based on his or her own experience, observation, or research.

In the latter case, the validity of the premise is tested by interrogation of the witness; in the former case, it is tested by inquiring into general acceptance. ¶ 63 This case turns on a non-scientific issue. As the Martone dissent concedes: In many respects, the phenomenon of repressed memory, whatever its validity, presents a classic problem for the law and science relationship____ [I]t remains woefully short of being empirically verified and, indeed, heralds from a non-rigorous school of psychology in which empirical validation is not a core tenet.

The theory of repressed memories has its roots in clinical therapy, a domain in which validity is not a factor of overriding concern---- Martone dissent at ¶ 86 (quoting 1 Faigman, et al. § 13-1.5, at 534). We believe the jury must decide what to do about the lack of empirical support. The June 11 Order would not even let the jury hear of the controversy and would, in effect, throw it and the case out of the courthouse, thus letting the judge decide the dispute if Frye were applied, and perhaps even if Daubert were applied. But what is gained by that?

The need, as Professor Faigman describes it, is this: Repression, in short, is a testable hypothesis, but it has not yet been appropriately tested. Pending satisfactory studies, therefore, the most reasonable scientific position is to maintain skepticism. Martone dissent at ¶ 88 (quoting 1 Faigman, ET al. § 13-2.4, at 150 (Supp.1999)). ¶ 64 We agree. The most reasonable position, scientific or unscientific, is to maintain skepticism about Plaintiffs claims. Justice Martone also suggests this case should be tested “under some heightened form of evi-dentiary scrutiny.” Martone dissent at ¶ 88. Again we agree.

But we have no doubt there will be very stringent scrutiny by the time able defense counsel finishes cross-examining Plaintiff and her witnesses, including Doctor van der Kolk. We are quite sure also that the nature of the ease and the evidence produced by Defendant may well engender some skepticism in the minds of the jurors, just as it did with the trial judge. But as able as this trial judge is, and no matter how well founded his skepticism or ours, we believe the evidentiary testing should come from the adversary system and be decided by the jury. We make no constitutional pronouncement.

We simply differ from the dissenters in this: having faith in the jury system, we believe jurors can handle the problem. Whether or not the jury finds Plaintiffs claims well founded, we are willing to indulge the presumption that the jurors will probably be right, or at least as right as the trial judge, and we, might be on this and the many other difficult issues of fact that come before our courts.

More important, we believe the result we reach is in keeping with our system of justice and its preference for trial by jury on issues of fact. ¶ 65 Thus, we retain the Frye rule but continue to apply it as described in Hum-mert. We reject the Joiner/Kumho

interpretation of Fed.R.Evid. 702 and continue to apply Ariz.R.Evid. 702 as written and interpreted by our eases. The trial judge’s June 11, 1998 Minute Entry Order is vacated. The case may proceed in conformance with this opinion. CONCURRING: THOMAS A. ZLAKET, Chief Justice, and CHARLES E. JONES, Vice Chief Justice. . The second question accepted was whether, assuming Frye applied, the trial judge abused his discretion by concluding the theory of repressed memory, post-traumatic stress disorder, or dissociative amnesia did not meet the general acceptance test. The cases have split on that question.

See Martone dissent at ¶81. From the record. one might conclude that in finding a lack of general acceptance, the judge gave undue weight to the views of research psychologists and too little to those of clinicians — psychiatrists and psychologists — who work in the field. But we need not resolve the problem because we conclude that Frye was inapplicable. . That literature is quite conservative, consisting of a long list of references to articles written by qualified authorities and published in authoritative texts such as the DSM-IV, peer-reviewed American journals such as Comprehensive Psychiatry (an

article on post-traumatic stress disorder in Vietnam veterans) and Harvard Review of Psychiatry. Listed also were authoritative foreign publications such as Revue Generale des Sciences (France), Lancet (Britain), and the Proceedings of the Royal Society of Medicine (Britain). . The trial judge was probably referring to lack of corroboration in some of the cases reported in the literature; however, there may be corroborative evidence in the present case. Following publication of a newspaper

article about this case, two women came forward and reported other acts allegedly committed by Defendant. Defendant moved to preclude th

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