Jill MARSH, Petitioner, v. Robert Earl VALYOU, Jr., et al., Respondents, 977 So. 2d 543

PER CURIAM. In this case, we decide whether Frye v. United States, 293 F. 1013 (D.C.Cir.1923), applies to expert testimony causally linking trauma to fibromyalgia. We review Marsh v. Valyou, 917 So.2d 313 (Fla. 5th DCA 2005), which certified conflict with State Farm Mutual Automobile Insurance Co. v. Johnson, 880 So.2d 721 (Fla. 2d DCA 2004). In Marsh, the Fifth District Court of Appeal held that Frye does apply and, applying that test, held the testimony inadmissible. See Marsh, 917 So.2d at 327, 329. The. Second District Court of Appeal, on the other hand, concluded that Frye did not apply.

Johnson, 880 So.2d at 723. We have jurisdiction to resolve the certified conflict, see art. V, § 3(b)(4), Fla. Const., and granted review. See Marsh v. Valyou, 940 So.2d 1125 (Fla.2006) (granting review). We conclude that Frye does not apply to expert testimony causally linking trauma to fibromyalgia and that, even if it did, such testimony satisfies it. Therefore, we quash Marsh and approve the conflicting opinion in Johnson. I.

FACTS AND PROCEDURAL HISTORY After sustaining injuries in four separate car accidents between August 1995 and January 1998, the petitioner, Jill Marsh, filed a negligence action against a series of four defendants — the Valyous; the Burkes; PVC Holding Corp., d/b/a Avis Rent-a-Car (“Avis”); and Scott David Chilcut (no longer a party). Marsh, 917 So.2d at 315.

She claimed the accidents caused fibromyalgia, which is a “syndrome of widespread pain, a decreased pain threshold, and characteristic symptoms including non-restorative sleep, fatigue, stiffness, mood disturbance, irritable bowel syndrome, headache, paresthesias, and other less common features.” Id. (quoting Frederick Wolfe, et al., The Fibromyalgia Syndrome: A Consensus Report on Fibro-myalgia and Disability, 23 J. Rheumatolo-gy 534, 534 (1996) [hereinafter Consensus Report ]).

Avis moved to preclude Marsh from presenting expert testimony that the accidents caused her fibromyalgia, arguing that the testimony did not meet the Frye standard for admissibility because the premise that trauma can cause fibromyal-gia had not been generally accepted in the scientific community. Id. The trial court held a Frye hearing and, after reviewing numerous documents related to fibromyal-gia and hearing arguments of counsel, granted the motion. Id. at 315-17. It later became apparent that Marsh intended to introduce evidence that the accidents caused “myofascial pain syndrome” (MPS). Id. at 318.

Again, Avis challenged the testimony under Frye and the trial court precluded evidence of a causal link between trauma and MPS. Id. Marsh then announced she had no claims apart from fibromyalgia and MPS, and the trial court entered

summary judgment. Id. at 319. Petitioner appealed, arguing: (1) the evidence is “pure opinion testimony” not subject to Frye-, and (2) only the basis for an expert’s opinions is subject to Frye, not the opinions and deductions drawn from those principles. Id. The Fifth District rejected these arguments and affirmed'. Id. at 329. The district court likewise affirmed the order related to MPS.

During the pendency of the appeal, the Second District decided Johnson, holding that testimony that trauma from an automobile accident caused fibromyalgia is admissible as “ ‘pure opinion testimony’ based solely on the expert’s personal experience and training;” 880- So.2d at 723 (quoting U.S. Sugar Corp. v. Henson, 787 So.2d 3, 14 n. 10 (Fla. 1st DCA 2000), approved, 823 So.2d 104 (Fla.2002)).

The Fifth District disagreed, concluding that testimony that trauma caused the plaintiffs fibromyalgia requires “an underlying scientific assumption- — that trauma can canse fibromyalgia — which is not involved in pure opinion testimony eases,” and certified conflict with Johnson. Marsh, 917 So.2d at 327, 329. II. ANALYSIS For purposes of our review, the parties do not dispute Marsh’s diagnosis of fibro-myalgia, or that fibromyalgia is a legitimate condition. Instead, the issue is whether expert testimony causally linking trauma (the car accidents) to the onset of fibromyalgia is subject to the Frye test.

Below we first explain why the testimony is not subject to Frye; and then explain that, even if the testimony had to satisfy Frye, it does. A. Frye Does Not Apply Many years ago, the United States Court of Appeals for the District of Columbia Circuit established a test for admitting expert testimony that espoused new or novel theories. In Frye, 293 F. at 1013, the court considered the admissibility of expert testimony as to the result of a “systolic blood pressure deception test,” an early polygraph. The D.C.

Circuit held: 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 field in which it belongs.

We think the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made. Id. at 1014. Many state courts, as well as other federal courts, adopted the Frye test. See, e.g., 29 Charles Alan Wright & Victor James Gold, Federal Practice and Procedure § 6266 (1997) (recognizing that Frye was the “dominate [sic] standard for decades”); Alice B.

Lustre, Annotation, Post-Daubert Standards for Admissibility of Scientific and Other Expert Evidence in State Courts, 90 A.L.R. 5th 453, § 2 (2001) (“[Frye ] was quickly adopted by most states as well as the other federal courts.”). We expressly adopted Frye in Bundy v. State, 471 So.2d 9, 18 (Fla.1985), and Stokes v. State, 548 So.2d 188, 195 (Fla.1989). Seventy years after Frye, the United States Supreme Court held that the adoption of the Federal Rules of Evidence superseded the Frye test. See Daubert v. Merrell Dow Pharms., 509 U.S. 579, 587, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993).

Daubert adopted a different test for admissibility under which the Frye test— general acceptance in the scientific community — is simply one factor among several. Id. at 594, 113 S.Ct. 2786. Courts and commentators have since debated whether the Daubert standard is more lenient or more strict. See, e.g., Allison v. McGhan Med.

Corp., 184 F.3d 1300, 1312 (11th Cir. 1999) (“While Allison argues that the thrust of the Rules and of the Eleventh Circuit has been for liberal admissibility of evidence, she fails to appreciate the tempering qualities of Rules 403, 702 and 703 under Daubert and the fact that this Circuit has been twice overruled on Daubert decisions in precedent setting Supreme Court decisions in [General Electric Co. v] Joiner[, 522 U.S. 136, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997) ] and Kumho Tire [Co. v.

Carmichael, 526 U.S. 137, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999)], both of which imposed stricter admissibility standards than the Eleventh Circuit had deemed appropriate.”); Berry v. CSX Transp., Inc., 709 So.2d 552, 570 n. 16 (Fla. 1st DCA 1998) (“It is yet a matter of debate whether the Daubert test ... will be more liberal and allow more expert testimony than the Frye requirement. ...”); David E. Bernstein & Jeffrey D.

Jackson, The Daubert Trilogy in the States, 44 Jurimetrics J. 351, 352 (2004) (“Courts and commentators disagreed, however, regarding whether this ‘revolution’ in how judges were to go about deciding whether to admit scientific evidence would lead to more permissive or more restrictive admissibility rulings.”) (footnote omitted); Edward K. Cheng & Albert H. Yoon, Does Frye or Daubert Matter? A Study of Scientific Admissibility Standards, 91 Va.

L.Rev. 471, 471, 510 (2005) (questioning whether a state’s adoption of Frye or Daubert makes any practical difference, but noting that “[c]ommentators have extensively debated which is the stricter standard”). Some commentators have suggested that, in practice, it makes no difference which test is used. See, e.g., Cheng & Yoon, supra, at 510. Despite the Supreme Court’s decision in Daubert, we have since repeatedly reaffirmed our adherence to the Frye standard for admissibility of evidence. See, e.g., Ibar v.

State, 938 So.2d 451, 467 (Fla.2006) (“Florida courts do not follow Daubert, but instead follow the test set out in Frye.”), cert. denied, — U.S.—, 127 S.Ct. 1326, 167 L.Ed.2d 79 (2007); Brim v. State, 695 So.2d 268, 271-72 (Fla.1997) (“Despite the federal adoption of a more lenient standard in [Daubert ], we have maintained the higher standard of reliability as dictated by Frye.”)-, Hadden v.

State, 690 So.2d 573, 578 (Fla.1997) (“Our specific adoption of that test after the enactment of the evidence code manifests our intent to use the Frye test as the proper standard for admitting novel scientific evidence in Florida, even though the Frye test is not set forth in the evidence code.”); Flanagan v. State, 625 So.2d 827, 829 n. 2 (Fla.1993) (“We are mindful that the United States Supreme Court recently construed Rule 702 of the Federal Rules of Evidence as superseding the Frye test. However, Florida continues to adhere to the Frye test for admissibility of scientific opinions.”) (citation omitted).

Other states have adhered to Frye as well. See, e.g., Wright & Gold, supra, § 6266 (noting that many states have adopted Daubert, but others have declined to do so); Bernstein & Jackson, supra, at 356 (noting that Frye “remains the rule in a significant minority of states”); Cheng & Yoon, supra, at 473 (noting that a number of states have formally adopted Daubert, but many have chosen to retain the Frye standard).

Under Frye, “[t]he proponent of the evidence bears the burden of establishing by a preponderance of the evidence the general acceptance of the underlying scientific principles and methodology.” Castillo v. E.I. Du Pont De Nemours & Co., Inc., 854 So.2d 1264, 1268 (Fla.2003). We review Frye issues de novo, with general acceptance considered as of the time of the appeal. Id. “By definition, the Frye standard only applies when an expert attempts to render an opinion that is based upon new or novel scientific techniques.” U.S. Sugar Corp. v. Henson, 823 So.2d 104, 109 (Fla.2002) (emphasis added).

Therefore, we have recognized that Frye is inapplicable in the “vast majority” of cases. Id.; see also Rickgauer v. Sarkar, 804 So.2d 502, 504 (Fla. 5th DCA 2001) (“Most expert testimony is not subject to the Frye test.”). The expert medical causation testimony at issue here is not “new or novel.” The American College of Rheumatology published classification criteria for fibro-myalgia in 1990. Consensus Report, supra, at 534, 536 (“FM is widely accepted as a common generalized- pain syndrome associated with characteristic symptoms and the finding of generalized tenderness.

The 1990 ACR Criteria for the Classification of Fibromyalgia have been established and recommended for classification purposes in research studies.”) (footnote omitted). Marsh’s experts based their diagnoses and opinions about the cause of her fibromyalgia on a review of her medical history, clinical physical examinations, their own experience, published research, and differential diagnosis. Experts routinely form medical causation opinions based on their experience and training. See, e.g., Cordoba v.

Rodriguez, 939 So.2d 319, 322 (Fla. 4th DCA 2006) (“Medical expert testimony concerning the causation of a medical condition will be considered pure opinion testimony and admissible when it is based solely on the expert’s training and experience.”); Gelsthorpe v. Weinstein, 897 So.2d 504, 510 (Fla. 2d DCA 2005) (“[Mjedical expert testimony concerning the causation of a medical condition will be considered pure opinion testimony—and thus not subject to Frye analysis—when it is based solely on the expert’s training and experience.”); Fla. Power & Light Co. v.

Tursi 729 So.2d 995, 996 (Fla. 4th DCA 1999) (finding Frye inapplicable where the physician was qualified to testify about the cause of a cataract based on his knowledge and experience). And there is always the possibility that two experts may reach dissimilar opinions based on their individual experience. However, a disagreement among experts does not transform an ordinary opinion on medical causation into a new or novel principle subject to Frye.

See Gelsthorpe, 897 So.2d at 511 (recognizing that “a typical opinion on medical causation” should not be treated as a “new principle, subject to Frye analysis, simply because some other experts disagree with it and because the challenged expert does not rely on any specific authority to support his particular opinion”); Tursi, 729 So.2d at 997 (recognizing that an ophthalmologist’s opinion on causation was not based on “novel scientific evidence,” as “[i]t was no more novel than an orthopedist testifying that a neck injury, which did not manifest itself with symptoms until four years after a rear-end collision, was caused by the accident”); Berry, 709 So.2d at 571 (recognizing that the trial will be a battle of the experts and the fact that they derived their opinions from the same studies, but disagree on how to interpret them, is not a valid reason for excluding their testimony).

It is well-established that Frye is inapplicable to “pure opinion” testimony: [P]ure opinion testimony, such as an expert’s opinion that a defendant is incompetent, does not have to meet Frye, because this type of testimony is based on the expert’s personal experience and training. While cloaked with the credibility of the expert, this testimony is analyzed by the jury as it analyzes any other personal opinion or factual testimony by a witness. Flanagan, 625 So.2d at 828; see also Hadden, 690 So.2d at 579-80 (same); Herlihy v.

State, 927 So.2d 146, 148 (Fla. 1st DCA 2006) (“[A] diagnosis based on an expert’s opinion and experience, versus a specific scientific test, would not be subject to a Frye hearing.”); Gelsthorpe, 897 So.2d at 510-11 (finding Frye inapplicable to “pure opinion testimony based upon clinical experience” where the “testimony did not rely on any study, test, procedure, or methodology that constituted new or novel scientific evidence,” but instead was based on an analysis of medical records and differential diagnosis).

Because testimony causally linking trauma to fibromyalgia is based on the experts’ experience and training, it is “pure opinion” admissible without having to satisfy Frye. See Johnson, 880 So.2d at 723. Marsh’s experts did not base their opinions on new or novel scientific tests or procedures, and Respondents did not challenge the patient history, examination methods, clinical practices, or other methodologies upon which they did rely.

In fact, Respondents could not challenge the underlying methodology, as we have previously held that differential diagnosis is a generally accepted method for determining specific causation. Castillo, 854 So.2d at 1271; U.S. Sugar, 823 So.2d at 110 (“[TJhere is no question that the differential diagnosis technique ... is generally accepted in the scientific community.”); see also Johnson, 880 So.2d at 723 (recognizing that a challenge to the underlying methodology would be unsuccessful because differential diagnosis is a “standard scientific technique”).

Instead, Respondents challenged the experts’ conclusions that trauma caused Marsh’s fibromyalgia. However, as we stated in U.S. Sugar, 823 So.2d at 110: [Ujnder Frye, the inquiry must focus only on the general acceptance of the scientific principles and methodologies upon which an expert relies in rendering his or her opinion. Certainly the opinion of the testifying expert need not be generally accepted as well.

Otherwise, the utility of expert testimony would be entirely erased, and “opinion” testimony would not be opinion at all — it would simply be the recitation, of recognized scientific principles to the fact finder.... We reaffirm our dedication to the principle that once the Frye test is satisfied through proof of general acceptance of the basis of an opinion, the expert’s opinions are to be evaluated by the finder of fact and are properly assessed as a matter of weight, not admissibility.

See also Castillo, 854 So.2d at 1276 (holding that the district court erred in considering “not just the underlying science, but the application of the data generated from that science in reaching the expert’s ultimate conclusion”); Berry, 709 So.2d at 567 (“[Wjhen the expert’s opinion is well-founded and based upon generally accepted scientific principles and methodology, it is not necessary that the expert’s opinion be generally accepted as well.”).

Trial courts must resist the temptation to usurp the jury’s role in evaluating the credibility of experts and choosing between legitimate but conflicting scientific views. See Castillo, 854 So.2d at 1275 (“[I]t is important to emphasize that the weight to be given to stated scientific theories, and the resolution of legitimate but competing scientific views, are matters appropriately entrusted to the trier of fact.”) (quoting Berry, 709 So.2d at 569 n. 14); Rodriguez v. Feinstein, 793 So.2d 1057, 1060 (Fla. 3d DCA 2001) (same).

A challenge to the conclusions of Marsh’s experts as to causation, rather than the methods used to reach those conclusions, is a proper issue for the trier of fact. See U.S. Sugar, 823 So.2d at 110; Castillo, 854 So.2d at 1270, 1272, 1276; Rodriguez, 793 So.2d at 1060 (recognizing that “to involve judges in an evaluation of the acceptability of an expert’s opinions and conclusions would convert judges into fact-finders” to an extent not contemplated by Florida’s Frye jurisprudence). For these reasons, we hold that Frye does not apply to testimony of a causal link between trauma and fibromyal-gia. B.

The Testimony Satisfies Frye Even if subject to Frye, testimony linking trauma to fibromyalgia satisfies it. The purpose of Frye is to ensure the reliability of expert testimony. See, e.g., Hadden, 690 So.2d at 578 (“Reliability is fundamental to issues involved in the admissibility of evidence.”); Berry, 709 So.2d at 568 (“At this admissibility stage of the proceedings, under Frye the court is asked to decide whether the basis of the evidence upon which plaintiffs’ experts rely has a sufficient indicia of reliability.”).

Numerous published articles and studies recognize an association between trauma and fibromyalgia. Respondents’ own expert testified that he has seen situations where he thought trauma indirectly led to fibromyalgia. A lack of studies conclusively demonstrating a causal link between trauma and fibromyalgia and calls for further research do not preclude admission of the testimony.

See Castillo, 854 So.2d at 1270 (“While epidemiology is considered generally accepted in the scientific community as a way of studying causal links between disease and chemicals, these types of studies are not necessarily required for a party to meet its burden of showing a causal link by a preponderance of the evidence.”); U.S.

Sugar, 823 So.2d at 110 (“[I]t is well settled that a lack of epidemiological studies does not defeat submission of expert testimony and opinions as expressed in this ease.”); Berry, 709 So.2d at 568 n. 12 (“[T]he fact that an epidemiological study calls for further research does not indicate uncertainty on the part of the researchers.”). Frye does not require unanimity. Brim, 695 So.2d at 272. While the precise etiology of fibromyalgia may not be fully understood, we hold that Marsh has sufficiently demonstrated the reliability of her experts’ testimony, and the trial court erred in excluding it.

See Berry, 709 So.2d at 568 (“While ... there continues to be scientific debate ... we find the epidemiological science and methodology underlying [the expert’s] testimony to be established, reliable, and well-founded.”). III. CONCLUSION For the reasons explained above, we hold that Frye does not apply to expert testimony causally linking trauma to fibro-myalgia. We further hold that, even if applicable, the testimony satisfies Frye. Therefore, we quash the Fifth District’s decision in Marsh, 917 So.2d at 313, and approve the Second District’s conflicting decision in Johnson, 880 So.2d at 721. It is so ordered.

LEWIS, C.J., and ANSTEAD, PARIENTE, and QUINCE, JJ., concur. ANSTEAD, J., specially concurs with an opinion, in which PARIENTE, J., concurs. CANTERO, J., dissents with an opinion, in which WELLS and BELL, JJ., concur. . Marsh apparently has abandoned the MPS issue, as it was not addressed at oral argument and was largely ignored in her briefs. Because the issue is beyond the scope of the certified conflict, we decline to address it. See Borden v. East-European Ins. Co., 921 So.2d 587, 596 n. 8 (Fla.2006) (recognizing an issue as beyond the scope of the certified conflict); Kelly v. Cmty.

Hosp. of the Palm Beaches, Inc., 818 So.2d 469, 470 n. 1 (Fla.2002) (declining to address issues beyond the basis for the Court’s conflict jurisdiction). . Differential diagnosis is “an established scientific methodology in which the expert eliminates possible causes of a medical condition to arrive at the conclusion as to the actual debilitating factor.” U.S. Sugar, 823 So.2d at 106. . See, e.g., A.W.

Al-Allaf et al., A Case-Control Study Examining the Role of Physical Trauma in the Onset of Fibromyalgia Syndrome, 41 Rheumatology 450, 452 (2002) (concluding that the results of the study suggested "that physical trauma was significantly associated with the onset” of fibromyalgia); Dan Buskila et al., Increased Rates of Fibromyalgia Following Cervical Spine Injury, 40 Arthritis & Rheumatism 446, 451 (1997) (concluding that "trauma to the neck is associated with a higher incidence of FMS”); Anil Kumar Jain et al., Fibromyalgia Syndrome: Canadian Clinical Working Case Definition, Diagnostic and Treatment Protocols' — A Consensus Document, 11 J.

Musculoskeletal Pain 3, 44 (2003) ("There is strong consistency in documentation that physical trauma such as a fall or motor vehicle accident, particularly a whiplash or spinal injury, can trigger FMS in some patients.”); Samuel A.

McLean et al., Fibromyalgia After Motor Vehicle Collision: Evidence and Implications, 6 Traffic Injury Prevention 97, 99 (2005) ("There is no disagreement regarding a close temporal association between [a motor vehicle collision] and the development of [fibromyalgia].”); Roland Staud, Fibromyalgia Pain: Do We Know the Source?, 16 Current Opinion in Rheumatolo-gy, 157, 158 (March 2004) (recognizing physical trauma as one of the "triggers” associated with fibromyalgia); Muhammad B. Yunus et al., Fibromyalgia Consensus Report: Additional Comments, 3 J.

Clinical Rheumatology 324, 325 (1997) ("[I]t seems more than 51% likely that trauma does play a causative role in some FMS patients....”).