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stating that, use of "magic language" is unnecessary to determine that the appropriate standard was applied
Summary of this case from In re KlionskyOpinion
No. 14 WAP 2019 No. 15 WAP 2019 No. 16 WAP 2019 No. 17 WAP 2019 No. 18 WAP 2019
07-21-2020
Richard Thomas WALSH, Executor of the ESTATE OF Thomas J. WALSH, Deceased v. BASF CORPORATION; Bayer Corporation d/b/a Bayer CropScience, L.P., and Bayer CropScience Holding, Inc., and/or Bayer CropScience, L.P. and Bayer CropScience Holding, Inc., in their own right; Biosafe Systems, L.L.C.; Chemtura Corporation; Cleary Chemical Corp. ; Dow Agrosciences, L.L.C.; E.H. Griffith, Inc. ; E.I. Du Pont De Nemours and Co., Inc.; G.B. Biosciences Corporation; John Deere Landscaping, Inc., Successor To Lesco, Inc.; Monsanto Company; Nufarm Americas, Inc.; Regal Chemical Co.; Scotts-Sierra Crop Protection Co. ; and Syngenta Crop Protection, Inc. Appeal of: Dow Agrosciences, LLC, Bayer CropScience, LP, Bayer Corporation, and Bayer CropScience Holding, Inc. Richard Thomas Walsh, Executor of the Estate of Thomas J. Walsh, Deceased v. BASF Corporation; Bayer Corporation d/b/a Bayer CropScience, L.P., and Bayer CropScience Holding, Inc., and/or Bayer CropScience, L.P. and Bayer CropScience Holding, Inc., in their own right; Biosafe Systems, L.L.C.; Chemtura Corporation; Cleary Chemical Corp. ; Dow Agrosciences, L.L.C.; E.H. Griffith, Inc. ; E.I. Du Pont De Nemours and Co., Inc.; G.B. Biosciences Corporation; John Deere Landscaping, Inc., Successor to Lesco, Inc.; Monsanto Company; Nufarm Americas, Inc.; Regal Chemical Co.; Scotts-Sierra Crop Protection Co. ; and Syngenta Crop Protection, Inc. Appeal of: Deere & Company Richard Thomas Walsh, Executor of the Estate of Thomas J. Walsh, Deceased v. BASF Corporation; Bayer Corporation d/b/a Bayer CropScience, L.P., and Bayer CropScience Holding, Inc., and/or Bayer CropScience, L.P. and Bayer CropScience Holding, Inc., in their own right; Biosafe Systems, L.L.C.; Chemtura Corporation; Cleary Chemical Corp. ; Dow Agrosciences, L.L.C.; E.H. Griffith, Inc. ; E.I. Du Pont De Nemours and Co., Inc.; G.B. Biosciences Corporation; John Deere Landscaping, Inc., Successor To Lesco, Inc.; Monsanto Company; Nufarm Americas, Inc.; Regal Chemical Co.; Scotts-Sierra Crop Protection Co. ; and Syngenta Crop Protection, Inc. Appeal of: Syngenta Crop Protection, Inc. Richard Thomas Walsh, Executor of the Estate of Thomas J. Walsh, Deceased v. BASF Corporation; Bayer Corporation d/b/a Bayer CropScience, L.P., and Bayer CropScience Holding, Inc., and/or Bayer CropScience, L.P. and Bayer CropScience Holding, Inc., in their own right; Biosafe Systems, L.L.C.; Chemtura Corporation; Cleary Chemical Corp. ; Dow Agrosciences, L.L.C.; E.H. Griffith, Inc. ; E.I. Du Pont De Nemours and Co., Inc.; G.B. Biosciences Corporation; John Deere Landscaping, Inc., Successor To Lesco, Inc.; Monsanto Company; Nufarm Americas, Inc.; Regal Chemical Co.; Scotts-Sierra Crop Protection Co. ; and Syngenta Crop Protection, Inc. Appeal of: Monsanto Company Richard Thomas Walsh, Executor of the Estate of Thomas J. Walsh, Deceased v. BASF Corporation; Bayer Corporation d/b/a Bayer CropScience, L.P., and Bayer CropScience Holding, Inc., and/or Bayer CropScience, L.P. and Bayer CropScience Holding, Inc., in their own right; Biosafe Systems, L.L.C.; Chemtura Corporation; Cleary Chemical Corp. ; Dow Agrosciences, L.L.C.; E.H. Griffith, Inc. ; E.I. Du Pont De Nemours and Co., Inc.; G.B. Biosciences Corporation; John Deere Landscaping, Inc., Successor to Lesco, Inc.; Monsanto Company; Nufarm Americas, Inc.; Regal Chemical Co.; Scotts-Sierra Crop Protection Co. ; and Syngenta Crop Protection, Inc. Appeal of: BASF Corporation
OPINION
Appellants, the manufacturers of various pesticides, appeal from the decision of the Superior Court reversing the trial court's grant of summary judgment in their favor following the trial court's determination that the testimony of the experts proffered by Appellee, the Executor of the Estate of Thomas J. Walsh ("Walsh"), failed to satisfy the test set forth in Frye v. United States , 293 F. 1013 (D.C. Cir. 1923). For the reasons set forth herein, we affirm the Superior Court's ruling, with instructions that on remand to the trial court, the Appellants should be given the opportunity to renew their Frye motions for the reasons addressed in this Opinion.
Factual and Procedural Background
For nearly forty years, Walsh served as a groundskeeper and golf course superintendent at several Pittsburgh area golf courses. His work involved the regular application of various pesticides (primarily insecticides and fungicides) on the golf courses. Over this time, Walsh kept a detailed record of his activities regarding the pesticides he used, including a detailed log of the specific products and the dates of their applications. In addition, a coworker, Blaise Santoriello, testified with regard to Walsh's activities, including how the pesticides were applied, the protective gear they wore when doing so, what pesticides were used and in what concentrations. In the early years, gloves were the only protective gear that they used, although in later years they also wore overalls, rubber boots and masks. Eventually they began wearing disposable protective gear. Even with these protections, Santoriello explained, exposure to the dust from the pesticide products would occur while opening the bags and mixing the chemicals.
On October 5, 2008, Walsh was suffering from fever, chills, and a cough when he arrived at an emergency room. A bone marrow biopsy resulted in a diagnosis of Acute Myelogenous Leukemia ("AML"). Cytogenetic testing revealed significant chromosomal aberrations. On February 2, 2009, Walsh died. His treating oncologist, James Rossetti, D.O., later opined that Walsh's extensive exposure to pesticides raised a high degree of suspicion that said exposure played a significant role in the development of his AML.
Walsh's executor commenced this wrongful death and survival action against the manufacturers of various pesticides that he had applied during his career, asserting claims in strict products liability, negligence, and breach of warranty. Based upon a lack of expert testimony identifying various pesticides as substantial contributing factors in Walsh's death, the trial court granted summary judgment in favor of a large number of manufacturers. Appellants, the remaining manufacturers, manufacture fifteen pesticides products to which Walsh was exposed.
Three of the current Appellants, Bayer CropScience LP, Bayer Corporation and Bayer CropScience Holdings, Inc. (collectively "Bayer"), filed a Frye motion to exclude the testimony of the Executor's expert witnesses, Nachman Brautbar, M.D ("Dr. Brautbar") and April Zambelli-Weiner, Ph.D. ("Dr. Zambelli-Weiner"). The remaining defendants either joined Bayer's Frye motion or filed their own. In these motions, the Appellants alleged that Drs. Brautbar and Zambelli-Weiner failed to apply methodologies generally accepted in the relevant scientific communities.
See Pa.R.C.P. 207.1 ("Motion to Exclude Expert Testimony Which Relies upon Novel Scientific Evidence").
In his original expert report, Dr. Brautbar explained that "[k]nowledgeable physicians approach the question whether a person's disease was caused by a particular chemical by considering two separate, but related, questions." Brautbar Initial Report, 2/17/2014, at 13. The first question is whether the chemical can cause "the particular condition the person has" (general causation), and the second question is "whether a chemical that is capable of causing the condition that the person has actually caused the person's condition." Id. For general causation, Dr. Brautbar described the generally accepted methodology he employed as follows:
In his original expert report, Dr. Brautbar discussed the methodologies he employed and gave an overview of what the nine Bradford Hill factors entailed (discussed infra). In a supplemental expert report, Dr. Brautbar provided a thorough analysis of his observations and conclusions with respect to each factor. Brautbar Supplemental Report, 10/22/2015, at 3-13.
(1) identify all relevant studies, (2) read and critically evaluate all the relevant studies, (3) evaluate all the data based upon recognized scientific factors (the Bradford Hill viewpoints) and other factors relevant to the chemical and the disease; (4) exercise best professional judgment in reaching a conclusion on the issue of whether a particular chemical or class of chemicals can cause a particular disease; and (5) explain the factual basis and the reasoning supporting the conclusion.
Id.
With respect to causality, Dr. Brautbar indicated that he utilized the "Bradford Hill criteria" or "viewpoints," a set of nine factors used to determine whether a recognized association is in fact a causal link. Id. at 13-15 (citing Sir Austin Bradford Hill, The Environment and Disease: Association or Causation , Section of Occupational Medicine, at 295 (January 1965)). In his 1965 article, Sir Bradford Hill indicated that his new methodology was necessary to decide whether an observed association between a potential toxin and a particular disease was in fact the outcome of an actual causal relationship.
Sir Bradford Hill's focus at the time was to determine whether there was a causal relationship between smoking and lung cancer.
[M]ore often than not we are dependent upon our observation and enumeration of defined events for which we then seek antecedents. In other words, we see that the event B is associated with the environmental feature A, that, to take a specific example, some form of respiratory illness is associated with a dust in the environment. In what circumstances can we pass from this observed association to a verdict of causality ? Upon what basis should we proceed to do so?
Id. (emphasis in original).
After an association between agent and disease has been identified, the nine factors are evaluated to determine the strength of that association, with a strong association pointing to a causal relationship. Sir Bradford Hill explained the process as follows:
Here then are nine different viewpoints from all of which we should study association before we cry causation. What I do not believe – and this has been suggested is that that we can usefully lay down some hard-and-fast rules of evidence that must be obeyed before we accept cause and effect. None of my nine viewpoints can bring indisputable evidence for and against the cause-and-effect hypothesis and none can be required as a sine qua non. What they can do, with greater or less strength, is help us to make up our minds on the fundamental question – is there any other way of explaining the set of facts before us, is there any other answer equally, or more, likely than cause and effect.
Id. at 299.
The nine criteria are (1) consistency of the observed association, (2) strength of the observed association, (3) specificity of the observed association, (4) temporal relationship of the observed association, (5) biological gradient, (6) biological plausibility, (7) coherence, (8) experimental evidence from human populations, and (9) analogy. Id. at 295-99. According to Dr. Brautbar, these criteria are widely accepted in the relevant scientific community, including by scientific bodies (e.g., the World Health Organization) and in modern textbooks on epidemiology, occupational and environmental medicine, and toxicology. Brautbar Initial Report, 2/17/2014, at 15-16. Dr. Brautbar stresses that there is no formula or algorithm for assessing the factors, but rather it requires judgment and scientific expertise to measure the weight and significance of each factor when conducting a particular evaluation. Id. at 16-17.
In his original expert report, Dr. Brautbar provided an overview of what the nine Bradford Hill factors entailed, and then a supplemental expert report filed after the reports of the Appellants’ experts had been received. In the supplemental report, Dr. Brautbar provided a detailed analysis of his observations and conclusions with respect to each factor, including "the facts and studies that I rely on [to] provide evidence supportive of causality under each of the Bradford Hill factors... ." Brautbar Supplemental Report, 10/22/2015, at 2. In this supplemental report, he observed that all of the experts in the case agreed that the Bradford Hill factors was the appropriate methodology to assess causation in this case. Id. He explained that the differing conclusions of the Appellants’ experts "is due to differences in professional judgment, rather than methodology," indicating that "different experts may reach differing conclusions based upon their best exercise of professional judgment, even though they may employ the same generally accepted methodology, they may rely on generally the same body of literature, and may base their opinion on the same facts relative to the patient and the workplace." Id.
Dr. Brautbar conducted his Bradford Hill factors analysis on the association between AML and pesticides. While conducting his analysis, he did not mention the pesticides manufactured by any of the Appellants or refer to any articles or studies relating to any specific pesticide or product. Having concluded that the Bradford Hill factors supported the existence of a causal link between AML and pesticides generally, he then acknowledged that because "some pesticides cause [AML] does not necessarily mean that all pesticides cause this disease." Id. He proceeded to conduct product-specific analyses of each product manufactured by the Appellants, including detailed tables attached to his report identifying every exposure that Walsh had to each product (including by date and specific product) (hereinafter "Exhibit B" ) as well as the carcinogenic potential for the active ingredients in each product (hereinafter "Exhibit C" ). He did not purport to present direct evidence of a causal link between AML and the Appellants’ specific products. Instead Dr. Brautbar opined that the causal link could be demonstrated indirectly. In particular, he identified studies that demonstrated that the active ingredients in these specific pesticides are genotoxic and thus cause chromosomal abnormalities. In what he refers to as the "fingerprint theory," he cited to studies showing that when exposure to pesticides or benzene causes AML, cytogenetic review identifies a unique set of chromosomal abnormalities (abnormalities of the fifth and seventh chromosomes), which in turn start the process to carcinogenicity. Brautbar Initial Report, 2/17/2014, at 22. According to Dr. Brautbar, this specific pattern of chromosomal abnormalities were identified in the cytogenetic testing performed on Walsh.
Exhibit B sets forth, in column form, the company and pesticide, toxicity per MSDS, Thomas Walsh exposure history per Complaint, pages of deposition, and a summary of testimony of co-worker (Santoriello).
Exhibit C sets forth, in column form, the company, product, composition, EPA cancer classification, human cancer, animal carcinogen, and cytogenicity, cytotoxicity, genotoxicity and immunotoxicity.
For specific causation, Dr. Brautbar utilized a differential diagnosis (or differential etiology) methodology, which he explained involves "ruling in all identifiable known causes of (and risk factors for) [the disease in question] and then ruling out those for which there is inadequate evidence." Id. at 61. According to Dr. Brautbar, "[t]he remaining cause(s) would then be deemed the probable cause(s) provided that substantial scientific and medical evidence exists for causality." Id .
Dr. Zambelli-Weiner conducted what she described as a critical review of "the published epidemiological literature on pesticide exposure and leukemia." Zambelli-Weiner Report, 7/18/2012, at 4. She indicated that in assessing the causal assessment, she employed a variety of methodologies, "including reviews, meth-analysis, weight-of-the-evidence analyses and application of the Bradford Hill criteria for causality." Id. at 5. She concluded that "exposure to organophosphate pesticide formulations, individually or in combination, is causally related to an increased risk of leukemia in humans exposed to them." Id. at 15.
The trial court did not conduct a Frye hearing, but rather ordered the parties to conduct depositions and file briefs. Upon review of these materials and after oral arguments by counsel, the trial court granted the Appellants’ Frye motions by written opinion. It first concluded that Dr. Brautbar's expert report did not establish either general or specific causation for pesticides not containing benzene. Trial Court Opinion, 10/5/2016, at 2-13. With respect to pesticides containing benzene, the trial court determined that Dr. Brautbar's expert report demonstrated general causation, as it cited to numerous studies showing that exposure to benzene "at some level" may cause AML. Id. at 13-19. The trial court rejected Dr. Brautbar's specific causation analysis with regard to benzene products, however, because it concluded that the reports and studies he cited did not support the contention that low level exposures of benzene could cause AML. Id. at 13-17. The trial court also refused to credit Dr. Brautbar's alternative theory of specific causation, namely the "fingerprint theory" that Dr. Brautbar claimed resulted in no cases of idiopathic instances of AML (no known external cause). Id. at 18-19.
Because Dr. Brautbar's expert report did not establish specific causation for any of the Appellants’ products, the trial court decided that it was not necessary to consider Dr. Zambelli-Weiner's expert report (which was offered only for general causation purposes). Id. at 19. The trial court noted that it did not consider Dr. Zambelli-Weiner's "pesticides as a class" opinion to be in accordance with generally accepted scientific methodology "because it fails to account for variations in composition of the universe of chemicals, compounds, or the like that might be considered a pesticide." Id. The trial court did not cite to any authority or expert testimony of record in support of this conclusion.
In light of the trial court's grant of the Appellants’ Frye motions, the parties stipulated to the entry of summary judgment "in favor of all remaining defendants and against [Walsh] on all of [Walsh's] remaining claims, ... with all rights of appeal preserved." Stipulated Order of Court, 19/14/2016.
The Executor then appealed to the Superior Court and the trial court issued a Pa.R.A.P. 1925(a) opinion. The Superior Court reversed the trial court's grant of the Appellants’ Frye motions. Walsh v. BASF Corp. , 191 A.3d 838 (Pa. Super. 2018), appeal granted , ––– Pa. ––––, 203 A.3d 976 (2019). It began by denying the Executor's contention that the causal relationship "has crossed the threshold from novel science to general acceptance." Id. at 844. Despite acknowledging that there are more than 700 scholarly articles and studies examining this causal relationship, the Superior Court recognized that in Betz v. Pneumo Abex LLC , 615 Pa. 504, 44 A.3d 27 (2012), this Court indicated that "a reasonably broad meaning should be ascribed to the term ‘novel,’ " and that application of the Frye standard is necessary when a trial court has "articulable grounds to believe that an expert has not applied generally accepted scientific methodology in a conventional fashion in reaching his conclusions." Id. (citing Betz , 44 A.3d at 47 ). Because some of Appellants’ experts had opined that the Executor's experts had not applied generally accepted methodologies in a conventional way, the Superior Court concluded that the trial court did not abuse its discretion in conducting a Frye inquiry. Id.
However, the Superior Court held that the trial court, by making itself the arbiter of what research could be scientifically relied upon to support an expert's opinion, had overstepped its "gatekeeper" function because that is "not the proper role of the trial court in a Frye inquiry." Id. at 844. The Superior Court cited to this Court's decision in Commonwealth v. Topa , 471 Pa. 223, 369 A.2d 1277 (1977), in which we indicated that we adopted the Frye test to avoid having judges try to understand the complexities of modern science, as it is better to allow the scientists to do that to ensure reliability. Id. at 842-43 (citing Topa , 369 A.2d at 1282 ).
The Superior Court further rejected the trial court's determination that the research relied upon by Dr. Brautbar was not scientifically acceptable because, on some occasions, the conclusion of the study's author were contrary to those of Dr. Brautbar. Id. at 843. The court cited to a dissent by then-Chief Justice Castille in Blum v. Merrell Dow Pharma., Inc. , 564 Pa. 3, 764 A.2d 1 (2000), in which he noted that limiting an expert testifying to the conclusions of other scientists would conclusively set in stone the views of the first researcher. Walsh , 191 A.3d at 846 (citing Blum , 764 A.2d at 15 (Castille, J., dissenting)). Instead, any conclusion reached by application of generally acceptable methodologies meets the Frye test.
The Appellants argued that generally accepted methodologies do not permit a scientist to extrapolate from studies involving harm from a broad product class (pesticides) to a specific product (Appellant's chemicals) causing a specific harm (AML). In other words, the Appellants indicated that Dr. Brautbar needed to rely on studies identifying a causal link between their specific product and AML. The Appellants likewise insisted that it was inappropriate for Dr. Brautbar to rely upon animal studies or in vitro (test tube) experiments instead of epidemiology studies involving humans.
As to the first point, the Superior Court held that an expert need not rely on studies that mirror the exact facts under consideration. Id. at 848. It is sufficient if the synthesis of various legitimate studies reasonably permits the conclusion reached by the expert. Id. The absence of a treatise or study directly on point goes to the weight, not the admissibility, of expert opinion. Id. An expert's opinion will satisfy Frye when it is deduced from generally acceptable scientific principles and supported by studies or literature, even where the expert could not point to one study involving precisely parallel circumstances. Id. The Superior Court disagreed that studies of Appellant's particular products were required, as the EPA regularly conducts studies on the cumulative risk of broad classes of pesticides that share similar "mechanisms of toxicity or act the same way in the body." Id. at 847. Many of the articles/studies by the Executor's experts looked at multiple pesticide exposures in agricultural settings, based upon the notion that this approach presents a better picture of occupational exposure to various pesticides (which are typically used in combination rather than singularly). Id. Zambelli-Weiner's expert report indicated that most epidemiological studies are conducted on exposures to classes of pesticides because they are "additive, cumulative, and synergetic." Id.
As to the second point, the Superior Court noted that scientists routinely conduct and rely upon animal studies and/or in vitro testing. Id. at 847. Dr. Brautbar did not rely exclusively on such studies. Id. Dr. Brautbar also relied upon human studies of pesticide exposure by golf course superintendents (like Walsh), farmers, and other pesticide applicators subject to occupational pesticides. Id. According to the court, all of these studies, in the aggregate, support a causal link between pesticide exposure and leukemia (including AML).
Finally, the Superior Court responded to the trial court's rejection of Dr. Brautbar's opinion that medical science, in the form of cytogenetic studies of chromosomal aberrations, was proof of a causal link resulting in AML. The trial court indicated that these studies were not conclusive but the Superior Court disagreed, indicating that "we find the existence of these studies, together with the differential etiology methodology employed by Dr. Brautbar, sufficient to pass muster under Frye . Id. at 848".
In dissent, Judge Bender held that that the trial court's review of the studies relied upon by Plaintiff's experts was "necessary to prevent experts from ‘evad[ing] a reasoned Frye inquiry by making reference to accepted methods in the abstract.’ " Id. at 849 (Bender, J., dissenting). According to Judge Bender, "more particularity is necessary" than the pesticide class methodology deemed sufficient by the majority. Id . at 850.
On appeal, the Appellants raise three issues:
I. Did the Superior Court majority commit reversible error in concluding that, when evaluating scientific evidence under the Frye standard, trial courts are not permitted to act as "gatekeepers" to ensure the relevance and reliability of scientific studies offered by experts to support their opinions by scrutinizing whether those studies actually support their opinions?
II. Did the Superior Court majority commit reversible error in concluding that trial courts may not review experts’ opinions extrapolating from a broad class of products and injuries to a specific product and injury, thereby eliminating plaintiff's burden to show product-specific causation of plaintiff's specific injury?
III. Did the Superior Court majority commit reversible error in concluding that the trial court erred without explaining how it abused its discretion because of manifest unreasonableness, partiality, prejudice, bias, ill-will or such lack of support from the evidence or the record so as to be clearly erroneous?
Walsh v. BASF Corp. , ––– Pa. ––––, 203 A.3d 976 (2019). Although technically the trial court granted summary judgment by consent of the parties, its ruling was based upon its interlocutory decision on the Appellants’ Frye motions. The appropriate appellate standard of review is typically the one pertaining to the underlying ruling. See Gallagher v. PLCB, 584 Pa. 362, 883 A.2d 550, 559 n.11 (2005). When reviewing a trial court's grant or denial of a Frye motion, an abuse of discretion standard applies. Betz , 44 A.3d at 54. Accordingly, we will apply an abuse of discretion standard in our review of the trial court's grant of the Appellants’ Frye motions.
We begin our discussion with Rule 702 of the Pennsylvania Rules of Evidence. Rule 702, entitled "Testimony by experts," which controls the admissibility of expert testimony on scientific knowledge, states:
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: (a) the expert's scientific, technical, or other specialized knowledge is beyond that possessed by the average layperson; (b) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; and (c) the expert's methodology is generally accepted in the relevant field .
Pa.R.E. 702 (emphasis added).
The requirement that the expert's methodology be generally accepted is commonly referred to as the Frye test. First announced in Frye v. United States , 293 F. at 1013, it was adopted by this Court in Pennsylvania in Topa . In Grady v. Frito-Lay, Inc. , 576 Pa. 546, 839 A.2d 1038, 1047 (2003), we clarified that the Frye rule "applies to an expert's method, not his conclusions." As artfully stated by former Chief Justice Cappy,
The Frye standard is limited to an inquiry into whether the methodologies by which the scientist has reached her conclusions have been generally accepted in the scientific community... . It restricts the scientific evidence which may be admitted as it ensures that the proffered evidence results from scientific research which has been conducted in a fashion that is generally recognized as being sound, and is not the fanciful creations of a renegade researcher. Yet, such a standard is not senselessly restrictive for it allows a scientist to testify as to new conclusions which have emerged during the course of properly conducted research.
Blum , 764 A.2d at 9 (Cappy, C.J., dissenting) (emphasis in original). The proponent of the admission of expert scientific evidence bears the burden of establishing all of the elements supporting its admission, including the general acceptance of the methodology employed in the relevant scientific community. Grady , 839 A.2d at 1045 ; Betz , 44 A.3d at 54. While the methodologies employed by the expert must be generally accepted, the conclusions reached from those applications need not also be generally accepted. Trach v. Fellin , 817 A.2d 1102, 1112 (Pa. Super. 2003) (en banc).
The Court in Grady made clear that whether a methodology is generally accepted in the relevant scientific community is a determination that has to be made based on the testimony of the scientists in that community, not upon any scientific expertise of judges.
One of the primary reasons we embraced the Frye test in Topa was its assurance that judges would be guided by scientists when assessing the reliability of a scientific method. See Topa , 369 A.2d at 1281 (quoting
United States v. Addison , 498 F.2d 741, 744 (D.C.Cir. 1974) ). Given the ever-increasing complexity of scientific advances, this assurance is at least as compelling today as it was in 1977, when we decided that case. We believe now, as we did then, that requiring judges to pay deference to the conclusions of those who are in the best position to evaluate the merits of scientific theory and technique when ruling on the admissibility of scientific proof, as the Frye rule requires, is the better way of insuring that only reliable expert scientific evidence is admitted at trial.
Grady, 839 A.2d at 1044–45 ; see also id. at 1045 ("This does not mean, however, that the proponent must prove that the scientific community has also generally accepted the expert's conclusion. ... This, in our view, is the sensible approach, for it imposes appropriate restrictions on the admission of scientific evidence, without stifling creativity and innovative thought.").
In Betz , this Court described the trial court's role in a Frye hearing as deciding whether "an expert witness has ... applied accepted scientific methodology in a conventional way in reaching his or her conclusions." 44 A.3d at 53. As noted by the concurring Justice, this language could be viewed as interjecting an element of the Daubert standard into our otherwise steadfast adherence to Frye ’s teaching that the expert's methodology be "generally accepted in the relevant field." Concurring Op. at 472 n.13. The dissenting Justice outright disagrees with the notion that the "conventional fashion" language was used in Betz to redefine Frye ’s general acceptance standard. Instead, the dissenting Justice indicates that this terminology was used only to identify novel science for the purpose of determining whether to conduct a Frye hearing. Dissenting Op. at 481–82.
Accepting both the concurring Justice's view that the phraseology may be confusing and the dissenting Justice's opinion that its use was not intended to modify the Frye general acceptance standard, we will not use the "conventional fashion" language in our discussion. Here, the novelty of the science has been conceded by Appellee, who did not appeal the Superior Court's determination that the science was novel.
Relatedly, with respect to causation issues, the Superior Court has offered the following:
Judges, both trial and appellate, have no special competence to resolve the complex and refractory causal issues raised by the attempt to link low-level exposure to toxic chemicals with human disease. On questions such as these, which stand at the frontier of current medical and epidemiological inquiry, if experts are willing to testify that such a link exists, it is for the jury to decide whether to credit such testimony.
Trach, 817 A.2d at 1117 (emphasis added) (quoting Ferebee v. Chevron Chemical Co. , 736 A.2d 1529, 1534 (D.C. Cir. 1984) ).
Issue One: Did the Superior Court majority commit reversible error in concluding that, when evaluating scientific evidence under the Frye standard, trial courts are not permitted to act as "gatekeepers" to ensure the relevance and reliability of scientific studies offered by experts to support their opinions by scrutinizing whether those studies actually support their opinions?
For their first issue on appeal, the Appellants contend that the Superior Court erred in ruling that the trial court had improperly exceeded its boundaries by reviewing in detail the studies that Dr. Brautbar relied upon in reaching his expert opinions. The Appellants posit that the Superior Court improperly held that in Frye proceedings trial courts are not "gatekeepers," as that is precisely the role that they play. Appellants’ Brief at 21 (citing Blum ex rel. Blum v. Merrell Dow Pharmaceuticals, Inc. , 705 A.2d 1314, 1322 (Pa. Super. 1997) ("[T]he judge as gatekeeper decides whether the expert is offering sufficiently reliable, solid, trustworthy evidence.")), affirmed , 564 Pa. 3, 764 A.2d 1 (2000). According to the Appellants, in past cases this Court has approved of careful review of the studies and evidence relied upon by an expert to assess relevance and reliability. Appellants’ Reply Brief at 5-8 (citing, e.g., Betz ).
In contrast, the Executor supports the Superior Court's contention that trial courts are not "gatekeepers." The Executor claims that the Superior Court did not rule that a trial court may not review studies or other evidence relied upon by an expert. Instead, the Executor contends that rather than merely reviewing the studies cited by Dr. Brautbar, the trial court made a number of bald assertions regarding the relevance and validity of said studies to Dr. Brautbar's proposed scientific opinions. Executor's Brief at 4. The Executor insists that the trial court, by analyzing the scientific literature on its own, "delved into an area beyond the training and experience of judges and lawyers and substituted its analysis of the scientific literature for the analysis that was conducted by [Executor's] experts." Id. at 7, 764 A.2d 1.
Whether we refer to the role of the trial court in a Frye contest as that of a "gatekeeper" is not consequential. What is of consequence is the role that the trial court plays during Frye proceedings. A careful review of our prior Frye decisions makes clear that it is the trial court's proper function to ensure that the expert has applied a generally accepted scientific methodology to reach his or her scientific conclusions. To fulfill this function, the trial court must be guided by scientists in the relevant field, including the experts retained by the parties in the case and any other evidence of general acceptance presented by the parties (e.g., textbooks). Conversely, trial courts may not question the merits of the expert's scientific theories, techniques or conclusions, and it is no part of the trial court's function to assess whether it considers those theories, techniques and/or conclusions to be accurate or reliable based upon the available facts and data. As is plainly set forth in Rule 702(c), the trial court's role is strictly limited to determining whether "the expert's methodology is generally accepted in the relevant field." Pa.R.E. 702(c). The trial court may consider only whether the expert applied methodologies generally accepted in the relevant field, and may not go further to attempt to determine whether it agrees with the expert's application of those methodologies or whether the expert's conclusions have sufficient factual support. Those are questions for the jury to decide.
To the extent that Pennsylvania trial courts conduct an "essential review for reliability," Dissenting Op. at 480, that review may consist only of establishing that the expert utilized generally accepted methodologies in reaching his or her scientific conclusions. Under Frye , requiring that an expert employ generally accepted methodologies is, in and of itself, the means by which Pennsylvania courts ensure that only reliable scientific evidence is presented to juries. See, e.g. , Topa , 369 A.2d at 1282 ("The requirement of general acceptance in the scientific community assures that those most qualified to assess the general validity of a scientific method will have the determinative voice."); Grady , 839 A.2d at 1045 ("We believe now, as we did then, that requiring judges to pay deference to the conclusions of those who are in the best position to evaluate the merits of scientific theory and technique when ruling on the admissibility of scientific proof, as the Frye rule requires, is the better way of insuring that only reliable expert scientific evidence is admitted at trial.").
Judges typically have no specialized training that qualifies them to weigh in on the expert's resolution of the highly complex issues involved in the determination of the causality of human disease resulting from exposure to specific toxins. By requiring the scientists addressing those issues to utilize generally accepted methodologies, the trial court conducting a Frye hearing ensures that the jury receives scientific opinion that is the result of sound research, while simultaneously leaving sufficient flexibility for new research to arrive at new conclusions previously uncredited.
Based upon our review, we must agree with the Superior Court's assessment that the trial court's Frye inquiry was at times "overly expansive." Walsh , 191 A.3d at 844. For example, the trial court rejected as scientifically unacceptable "animal studies, test-tube studies and studies that include significant limiting language as to the applicability of their results to causation theories." Trial Court Opinion, 10/5/2016, at 12-13. According to the trial court, it is not generally accepted methodology "to select portions of studies that favor a certain outcome while ignoring direct statements against that outcome within the same article." Id. In so ruling, however, the trial court did so unilaterally, without citation to any authority or to the voluminous expert deposition testimony in the certified record. Whether it was in accordance with generally accepted methodology to rely upon animal and/or test tube studies of the sorts cited on Dr. Brautbar's Exhibit C (evaluating the genotoxicity of the active ingredients in the Appellants’ products) constituted a scientific judgment that must be guided by the experts, not a trial court. Similarly, whether Dr. Brautbar could rely upon articles containing limiting language would depend upon the precise nature of that limiting language and the purpose for which Dr. Brautbar was relying upon it. Again, it was not the province of the trial court, but rather the scientists (including Dr. Brautbar), to guide this decision. The trial court's role was limited to determining whether Dr. Brautbar reached his scientific conclusions by applying generally accepted scientific methodologies.
The Appellants point out that this Court in Betz discounted the usefulness of these types of evidence in a substantial cause analysis. Betz , 44 A.3d at 55. That assessment was, however, obviously based upon the evidence of record (including expert deposition testimony) in that case, and the manner in which the expert was attempting to use such studies when formulating his conclusions. In baldly rejecting "animal studies, test-tube studies and studies that include significant limiting language," the trial court did not refer to the certified record in this case or to any other authority in support of its pronouncement.
The trial court likewise found it unacceptable for Dr. Brautbar to rely on studies that did not reach the same ultimate conclusion reached by Dr. Brautbar, rejecting studies that did not identify a direct causal link between AML and a particular pesticide manufactured by one of the Appellants. The trial court acknowledged that Dr. Brautbar's opinion relied upon an indirect link between pesticides and AML, specifically that pesticide exposures result in specific chromosomal abnormalities (abnormalities of the fifth and seventh chromosomes), which in turn start the process to carcinogenicity that leads to leukemia (including AML). Brautbar Initial Report, 2/17/2014, at 22. After reviewing the studies Dr. Brautbar cited in support of his conclusions, however, the trial court rejected, as unsupported, Dr. Brautbar's scientific conclusion that "[c]hromosomal changes are like fingerprints of prior exposure" to certain types of chemicals, including pesticides and/or benzene. Id. at 21.
Dr. Brautbar's conclusion that specific patterns of chromosomal aberrations are like "fingerprints" was an important component in his product specific analyses by demonstrating that Walsh's exposure to pesticides and benzene was a substantial contributing cause of his AML, as per the detailed information in Exhibits B and C of his report. It was also important to his differential diagnosis, as it is his contention that "fingerprints" in chromosomal aberrations excluded a finding that Walsh's’ AML was idiopathic (without any known external cause). The trial court noted that Dr. Brautbar had relied upon (among others) a study by Cuneo that provided some support for the chromosomal aberrations theory based upon a comparison of individuals with AML divided into two groups (those exposed to pesticides and those not exposed). Cuneo concluded that "patients exposed to pesticides had the same recurring chromosomal aberrations and cytological features, which were different from those found in the unexposed group." Brautbar Initial Report. 2/17/2014, at 24 (citing Ontario College of Family Physicians, Leukemia (Chapter 5), Pesticides Literature Review (April 23, 2004), 49-50) (reviewing Cuneo, A., et al., Morphologic, Immunologic and Cytogenetic Studies in Acute Myeloid Leukemia Following Occupational Exposure to Pesticides and Organic Solvents , Leuk Res. 16:789-796 (1992)).
The trial court, however, noted that Cuneo's study did not show that individuals with AML in the exposed group always showed chromosomal aberrations to the fifth and seventh chromosomes, as the cytogenetic results of a few members of the exposed group did not demonstrate the identified pattern of aberrations. Trial Court Opinion, 10/5/2016, at 18-19. According to the trial court, this proved that there was no "fingerprint" of AML caused by exposure to pesticides and/or benzene. Id. In reaching this conclusion, the trial court did not consider Dr. Brautbar's deposition testimony, in which he explained at some length that Cuneo had used an older methodology for the identification of members of the exposed and unexposed groups and that the use of a newer methodology in fact demonstrates a chromosomal fingerprint in Cuneo's exposed group. Brautbar Deposition, 5/13/2014, at 364-79.
Importantly, the trial court's rejection of Dr. Brautbar's "fingerprint" conclusion was based solely upon its own analysis of the scientific studies proffered by Dr. Brautbar and not on any review of the methodology that Dr. Brautbar was utilizing to reach his conclusion. A focus on his methodology would have included consideration of both Dr. Brautbar's deposition testimony as well as that of the Appellants’ experts. Dr. Marshall Lichtman, for example, testified at his deposition that up to 85% of AML cases are idiopathic and that about half of them have no distinct pattern of chromosomal aberrations. Lichtman Deposition at 28. Dr. Lichtman further testified that in comparison to the Cuneo study, in which 21 patients were in the exposed group, Dr. Brautbar had not considered at least four larger subsequent studies (with more than 5,500 patients) which found cytogenetic abnormalities are not present in about half of de novo AML cases, and that as a result one cannot use the appearance of chromosomal abnormalities to reach the conclusion that the AML case must have been externally caused (e.g., by exposure to pesticides or benzene). Id. at 49-50. According to Dr. Lichtman, Dr. Brautbar did not follow a generally accepted scientific methodology by relying only on those studies that supported his conclusions while ignoring much larger studies that did not do so. Id.
The Appellants contend that in past cases this Court has approved of trial courts conducting their own intensely granular reviews of the scientific evidence offered by experts in support of their opinions. The Appellants argue that in Betz , the Court recognized that the trial court had considered "the testimony of the witnesses, voluminous scientific literature, and numerous legal authorities proffered in support of the plaintiffs’ and defendants’ respective positions." Betz , 44 A.3d at 39 (citing In re Toxic Substance Cases , 2006 WL 2404008, at *2 (C.P.Allegheny, Aug. 17, 2006) ). In so doing, however, and in contrast to the trial court in the case before us, this Court emphasized that the trial court's systemic review of the evidence was for the express purpose of deciding whether the expert witness had utilized a generally accepted methodology . Id. at 39 ("Focusing upon methodology , Judge Colville found no support for the any-exposure theory of specific causation in any of the sources upon which Dr. Maddox relied.") (emphasis added); id. at 40 ("Rather, [the trial court] agreed with the defendants' experts that Dr. Maddox's methodology was plagued by unwarranted liberties and logical errors." (emphasis added); id. at 53 ) ("[The trial court] spent considerable time listening to the attorneys' arguments but was unable to discern a coherent methodology supporting the notion that every single fiber from among, potentially, millions is substantially causative of disease.") (emphasis added).
In their Frye motions filed in the trial court, the Appellants raised this issue – whether Dr. Brautbar applied a generally accepted methodology to arrive at his cytogenetic "fingerprint" conclusion. See Defendants’ Joint Brief in Support of Motions to Exclude Expert Testimony of April Zambelli-Weiner and Nachman Brautbar, 3/9/2016, at 2-5. The trial court issued no ruling on the issue. The Appellants also questioned whether Dr. Brautbar and/or Dr. Zambelli-Weiner utilized a generally accepted methodology when they applied the Bradford Hill criteria to establish causation to "pesticides-as-a-class" rather than to their individual products, by applying certain of the Bradford Hill factors contrary to the ways in which Sir Bradford Hill intended for them to be applied (and ignoring others entirely), and by failing to identify any epidemiological studies demonstrating a causal association between AML and their specific products before engaging in the Bradford Hill methodology at all. Id. The Appellants contested Dr. Brautbar's methodology of opining on specific causation without first establishing the specific dose at which their products could cause AML. Id. The Appellants contended that Drs. Brautbar and Zambelli-Weiner did not follow a generally accepted methodology by "cherry-picking" studies that supported their conclusions while ignoring other studies that did not. Id. Finally, the Appellants contested Dr. Brautbar's application of the differential diagnosis methodology when he failed to rule out a known cause of AML (obesity ). Id.
The trial court issued no rulings on any of these Frye challenges. To the contrary, in its initial opinion granting the Appellants’ Frye motions, the trial court did not even mention the Bradford Hill criteria or indicate that the Executor's experts (and at least one of the Appellants’ experts) were employing this methodology. In its subsequent Rule 1925(a) opinion, the trial court merely indicated that Dr. Brautbar's use of the Bradford Hill methodology required reliance upon peer-reviewed research, which it had already concluded "did not stand for the conclusions that Dr. Brautbar cited them for." Rule 1925(a) Opinion, 12/22/2016, at 5. By questioning the judgment of the Executor's experts and the reliability of their scientific conclusions, rather than focusing on whether the Executor satisfied his burden of proof that Drs. Zambelli-Weiner and Brautbar formed their opinions by application of methodologies that are generally accepted in the relevant fields of study, the trial court abused its discretion. Accordingly, we agree with the Superior Court's decision to vacate the trial court's orders granting the Appellants’ Frye motions and entering summary judgment. On remand, the Appellants should be afforded the opportunity to renew their Frye motions so that the relevant issues can be addressed. Issue Two: Did the Superior Court majority commit reversible error in concluding that trial courts may not review experts' opinions extrapolating from a broad class of products and injuries to a specific product and injury, thereby eliminating plaintiff's burden to show product-specific causation of plaintiff's specific injury?
For their second issue on appeal, the Appellants argue that the Superior Court held that experts can satisfy their burden under the Frye test by and through the unrestricted use of extrapolation. The Appellants insist that the Superior Court held that establishing a causal link between cancer and long-term exposure to "pesticides-as-a-class" is sufficient to support a causation decision regarding exposure to the specific pesticide products at issue in the case. The Appellants contend that under the Superior Court's analysis, if an expert can cite to literature suggesting that a class of products may cause a disease, then that expert has met his or her burden under Frye to opine that any particular product in that class caused the disease, regardless of the diversity between the various types of products within that class. According to the Appellants, the Superior Court's ruling ignores this Court's ruling in Betz , which established strong limitations on the use of extrapolation in substantial cause analyses and effectively eliminates the plaintiff's the burden to show product-specification.
The Appellants have misread the Superior Court's opinion, as it does not in any respect bless the unfettered use of extrapolation in a substantial cause analysis and it did not eliminate a plaintiff's burden to show product-specification. To the contrary, the Superior Court's principal focus was directed to the trial court's rejection of studies cited by Dr. Brautbar based upon its own conclusion that his reliance on them was not scientifically acceptable, either because the study did not identify a direct causal link between a particular Appellant's product and AML or because it reached a conclusion contrary to that ultimately reached by Dr. Brautbar. Walsh , 191 A.3d at 845-46. The trial court, in reviewing and analyzing the cited scientific articles, had "impermissibly set himself up ‘as a super expert in the field of medicine,’ " and had thus added an extra "layer to the generally accepted methodology requirement" that is not any part of a proper Frye analysis. Id. In response, the Superior Court properly indicated that the "absence of a treatise or study directly on point goes to the weight, not to the admissibility, of expert testimony," id. at 847, and further stated that "an expert is not required to parrot the conclusions of study authors." Id. at 846. The Superior Court likewise rejected any notion that a proper Frye causal analysis must include an epidemiological study demonstrating an increased incidence of AML after substantial exposures to their specific products (or the active ingredients in their specific products). Id. at 847-48 ("For purposes of Frye , an expert need not rely on studies that mirror the exact facts under consideration.").
In Trach , the Superior Court described extrapolation as a logical method used "to estimate the value of a variable outside its tabulated or observed range" or "to infer (that which is not known) from that which is known." Trach , 817 A.2d at 1114-16 (citing Donaldson v. Central Illinois Public Service Co. , 199 Ill.2d 63, 262 Ill.Dec. 854, 767 N.E.2d 314, 328–329 (2002) ("Extrapolation is commonly used by scientists in certain limited instances ..., for example, when the medical inquiry is new or the opportunities to examine a specific cause and effect relationship are limited; when the number of cases limits study of the disease; or ... when ethical considerations prevent exposing individuals to a toxic substance for research purposes.")). Given the breadth of these definitions of the term, except in those rare circumstances in which a perfectly comparable study supports a direct causal relationship between a particular agent and a disease, virtually every expert opinion on substantial causation will likely contain instances of the use of extrapolation. The Executor here does not contend that Drs. Zambelli-Weiner and Brautbar did not engage in the use of any extrapolation in formulating the opinions set forth in their expert reports. To the contrary, at his deposition Dr. Brautbar forthrightly admitted to his use of extrapolation in at least one respect, namely that "[e]xtrapolation from animal studies, extrapolation from cell studies, extrapolation from human cell studies to disease causation" are part of" the "mechanistic aspects to understanding causation of disease. (Brautbar Deposition, 5/13/2014, at 30-31).
Importantly for present purposes, however, our review of the expert reports of Drs. Zambelli-Weiner and Brautbar does not reflect that either of them used extrapolation in the manner now complained of by Appellants. Specifically, while both experts employed the Bradford Hill criteria to establish a causal link between cancer (or AML) and long-term exposure to pesticides, neither expert opined that this link wholly constituted product-specific causation between cancer and long-term exposure to the Appellants’ specific pesticide products. In her expert report, Dr. Zambelli-Weiner offered no opinions with regard to any of the Appellants’ specific products. To the contrary, at her deposition she expressly refused to answer questions about whether any of the Appellants’ specific products cause cancer /AML. Zambelli-Weiner Deposition, 9/23/2014, at 107-08; ("I was not charged with evaluating the association of any particular product ... with leukemia."); Id. , 9/24/2014, at 355 ("I wasn't tasked with studying chlorpyrifos specifically.").
Dr. Zambelli-Weiner's expert report sets forth three opinions:
1. Mr. Walsh had cumulative lifetime exposure days to pesticides consistent with exposure levels associated with increased risk of leukemia, and AML specifically, in published peer-reviewed literature.
2. It is my opinion, to a reasonable degree of medical certainty, that exposure to pesticide formulations, individually or in combination, is causally related to an increased risk of cancer in humans exposed to them.
3. It is my opinion, to a reasonable degree of scientific certainty, that exposure to organophosphate pesticide formulations, individually or in combination, is causally related to an increased risk of leukemia in humans exposed to them.
Zambelli-Weiner Report, 7/18/2012, at 13-15.
With respect to the Appellants’ Frye motions, we note that the trial court issued no ruling with respect to whether Dr. Zambelli-Weiner's failure to opine on whether the Appellants’ specific products may cause leukemia precludes her use as an expert on general causation at trial, and the Superior Court likewise did not address this issue. As a result the Superior Court's opinion, contrary to the assertions of Appellants, did not eliminate the plaintiff's burden to show product-specification. See Rost v. Ford Motor Co., 637 Pa. 625, 151 A.3d 1032, 1044 (2016) (Pennsylvania law requires that "to create a jury question, a plaintiff must adduce evidence that exposure to defendant's [product] was sufficient ... to support a jury's finding that defendant's product was substantially causative of the disease.").
The trial court stated that "I find that Dr. Zambelli-Weiner's general causation opinion regarding pesticides as a class is not in accordance with generally accepted scientific methodology because it fails to account for variations in composition of the universe of chemicals, compounds, or the like that might be considered a "pesticide." Trial Court Opinion, 10/5/2016, at 19. The trial court offered this observation as its own opinion, however, as it was not accompanied by citation to any scientific authority in the record in its support. Moreover, the remark must be considered to be mere dicta, as the trial court offered it only after having rejected Dr. Brautbar's opinion on specific causation opinions. Id. ("Because Dr. Brautbar's specific causation opinions are not formed using generally accepted scientific methodology, the viability of Dr. Zambelli-Weiner's general causation opinions is not material.").
As indicated, Dr. Brautbar also applied the Bradford Hill criteria to establish a causal link between AML and long-term exposure to pesticides. He did not extrapolate from this finding that because pesticides increase the risk of contracting AML that Appellants’ specific products likewise increase this risk. To the contrary, he disclaimed any use of this type of extrapolation, stating in his initial expert report "that some pesticides cause [AML] does not necessarily mean that all pesticides cause this disease." Brautbar Initial Report, 2/17/2014, at 18. He then proceeded to conduct product-specific analyses of each product manufactured by the Appellants, evaluating the chemical components of each of the pesticides individually and concluding that each of them contained chemicals that were genotoxic or caused DNA damage, and thus are carcinogenic. Id. at 21-23 and Exhibits B and C.
The Superior Court neither blessed the indiscriminate use of extrapolation nor adopted the Appellants’ contention that its opinion may fairly be read to hold that establishing a causal link between cancer and long-term exposure to pesticides is sufficient to support a causation decision regarding exposure to a defendant's specific product; rather, the Superior Court properly indicated that an expert need not rely on studies mirroring the exact facts under consideration, as a synthesis of various legitimate studies which reasonably permits experts’ conclusions may be sufficient for purposes of Frye. Walsh , 191 A.3d at 847-48. In our decision in Rost , this Court reaffirmed that the plaintiff has a burden to show product-specification. See Rost, 151 A.3d at 1044. The Superior Court's opinion may not be fairly read to alter that burden in any respect.
Issue Three: Did the Superior Court majority commit reversible error in concluding that the trial court erred without explaining how it abused its discretion because of manifest unreasonableness, partiality, prejudice, bias, ill-will or such lack of support from the evidence or the record so as to be clearly erroneous?
The Appellants argue that although the Superior Court found that the trial court erred, "it never actually stated that he abused his discretion." Appellants’ Brief at 59. The Appellants insist that the Superior Court failed to identify how the trial court erred and further allege that the Superior Court, rather than applying the abuse of discretion standard, instead substituted its own judgment for that of the trial court. Id.
We disagree. It is unnecessary for an appellate court to use any "magic language" when ruling that a lower court abused its discretion. It is enough for the appellate court to explain how the lower court abused its discretion. In our view, the Superior Court plainly set forth numerous abuses of discretion by the trial court, including its review of the scientific literature at a granular level to make its own bald judgments about which studies relied upon by Dr. Brautbar were scientifically acceptable, relevant and/or supportive of his conclusions. Walsh , 191 A.3d at 844-45. As the Superior Court correctly recognized, "[t]hat is not the proper role of the trial court in a Frye inquiry." Id. at 844.
As such, the Superior Court found the trial court's consideration of the Appellants’ Frye motions to be flawed in multiple respects and vacated the trial court's decision on that basis. We thus conclude that the Superior Court properly applied its standard of review.
The order of the Superior Court is affirmed. On remand to the trial court, the Appellants should be afforded the opportunity to renew their Frye motions for the reasons addressed in this Opinion.
Justices Dougherty, Wecht and Mundy join the opinion.
Justice Wecht files a concurring opinion.
Justice Baer files a concurring and dissenting opinion.
Chief Justice Saylor files a dissenting opinion in which Justice Todd joins.
CONCURRING OPINION
JUSTICE WECHT
The Majority's opinion, which I join, explains well the mischief that arises when trial judges overestimate their role as keepers of the gate through which expert evidence must pass. Pursuant to Pennsylvania's application of the Frye standard, a trial court determining whether to admit expert testimony may consider only whether the expert arrived at his opinion by employing principles and methods "generally accepted" in the relevant community of experts. Conversely, under the Daubert standard, the prevailing rubric in federal courts and in a majority of state courts, the trial court also may consider whether the expert "reliably applied" the methodology in question and whether the opinions and the conclusions that he or she reached are supported by "sufficient facts or data." See F.R.E. 702(d), (b) (respectively). For nearly thirty years, Pennsylvania has rejected Daubert ’s broader grant of authority—despite repeated invitations to adopt it. In my view, Frye continues to present the superior approach. I write separately because I am concerned that this Court's decision in Betz v. Pneumo Abex L.L.C. , 615 Pa. 504, 44 A.3d 27 (2012), in its reliance upon potentially misleading terminology, so muddied the waters that this Court should stabilize its characterization of the Frye standard as distinct from Daubert , leaving no unnecessary doubt regarding the limitations upon a trial court's discretion in assessing the admissibility of expert evidence. Because the lower court and Appellants alike relied upon Betz ’ problematic terminology, I would take this opportunity to set matters straight.
See Frye v. United States , 293 F. 1013 (D.C. 1923).
The deposition of Dr. Brautbar spanned four days, but the pagination for the transcript was continuous. For convenience, the deposition is referred to hereinafter as "N.B. at __."
See Daubert v. Merrell Dow Pharm., Inc. , 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). Daubert is the first in a "trilogy" of cases on the subject, consisting of Daubert and the United States Supreme Court's subsequent 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., Ltd. v. Carmichael , 526 U.S. 137, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999). See generally David E. Bernstein & Jeffrey D. Jackson, The Daubert Trilogy in the States , 44 Jurimetrics . J. 351 (2004).
See, e.g. , McClain v. Metabolife Int'l, Inc. , 401 F.3d 1233, 1241-42 (11th Cir. 2005) (relating that an expert's failure to lay a reliable groundwork for assessing the dose-response relationship in a toxic tort case "signals a methodological problem"); Burleson v. Tex. Dep't of Criminal Justice , 393 F.3d 577, 587 (5th Cir. 2004) (highlighting that a causation opinion where the expert "fail[s] to conduct a dose assessment" produces "too great an analytical gap between the data and the opinion proffered" (citation omitted)); Mitchell v. Gencorp, Inc. , 165 F.3d 778, 781 (10th Cir. 1999) ("[A] plaintiff must demonstrate the levels of exposure that are hazardous to human beings generally as well as the plaintiff's actual level of exposure to the defendant's toxic substance before he or she may recover."); Allen v. Pa. Eng'g Corp. , 102 F.3d 194, 199 (5th Cir. 1996) ("Scientific knowledge of the harmful level of exposure to a chemical, plus knowledge that the plaintiff was exposed to such quantities, are minimal facts necessary to sustain the plaintiffs’ burden in a toxic tort case."); Yates v. Ford Motor Co. , 113 F. Supp. 3d 841, 861 (E.D.N.C. 2015) ("Rather than engage in any specific, meaningful comparison of the scientific data with [the plaintiff's] exposures, [the expert's] opinions essentially attempt to overwhelm with statistics and studies, lacking guidance as to how a juror ought to apply them[, which] is not a reliable method, and it will not assist a jury.").
I acknowledge that -- from my point of view at least -- a majority of this Court has previously sanctioned the admissibility of an expert opinion pertaining to substantial-factor causation on terms that would not meet (or even approach) the standards maintained in these other courts. See Rost v. Ford Motor Co. , 637 Pa. 625, 666-76 & n.6, 151 A.3d 1032, 1057-63 & n.6 (2016) (Saylor, C.J., dissenting) (explaining, inter alia , that the relevant expert "made no attempt to even roughly quantify either the dose experienced by [the decedent at his place of employment] or his cumulative exposure or dose."). That decision, however, arose in the discrete setting of an asbestos-mesothelioma case, and it remains to be seen whether, or to what extent, the position will be transported beyond that unique arena.
As noted in his Dissenting Opinion, Chief Justice Saylor has in the past suggested some affinity for Daubert . See Diss. Op. at 476–77 (citing Commonwealth v. Smith , 606 Pa. 127, 995 A.2d 1143, 1177 (2010) (Saylor, J., concurring and dissenting)). In keeping with that, excepting Pennsylvania cases, virtually every case Chief Justice Saylor cites to support his substantive view in this case comes from a jurisdiction that adheres directly or in practice to the Daubert standard.
In terms of Dr. Brautbar's approach to the scientific studies, epidemiologist David H. Garabrant, M.D., testified that "scientists have an obligation to consider all relevant evidence and to weigh it." Deposition of David H. Garabrant, M.D., dated Jan. 7, 2016, at 42. Consistent with Judge Wettick's assessment, Dr. Garabrant explained that Dr. Brautbar neglected to do so and further failed to apply the Bradford Hill viewpoints which he invoked in a reliable manner. See id. at 101. Rather, Dr. Garabrant testified that Dr. Brautbar "cherry pick[ed]." Id. at 127. In particular, Dr. Brautbar "never mentions the absence of dose-response relationship in the studies that have examined it for the pesticides at issue. And so his claim that the dose-response data tends to support a causal relationship is not true for the pesticides at issue in this case and for leukemia." Id. at 131; see also id. at 134 (asserting that Dr. Brautbar "misinterpreted a number of the [Bradford Hill viewpoints], he's failed to support others, and he has invoked chemicals not at issue in this case and diseases not at issue in this case in support of his views"). Judge Wettick's close review of some of the studies involved parallels this line of criticism.
This Court's preference for the Frye test is embodied in Pennsylvania Rule of Evidence 702, which provides:
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: (a) the expert's scientific, technical, or other specialized knowledge is beyond that possessed by the average lay person; (b) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; and (c) the expert's methodology is generally accepted in the relevant field.
Pa.R.E. 702. Thus, when a party seeks to introduce an expert's testimony, the trial court must determine whether the principles and methodology employed by the expert in developing his or her opinion are generally accepted in the relevant field. By doing so, the court "ensures that the proffered evidence results from scientific research which has been conducted in a fashion that is generally recognized as being sound, and is not the fanciful creation[ ] of a renegade researcher." Blum ex rel. Blum v. Merrell Dow Pharm., Inc. , 564 Pa. 3, 764 A.2d 1, 9-10 (2000) (Cappy, J., dissenting).
As the Majority observes, the proponent bears the burden of establishing that the proffered testimony satisfies all three prongs of Rule 702. See Maj. Op. at 456 (citing Grady v. Frito-Lay, Inc. , 576 Pa. 546, 839 A.2d 1038, 1045 (2003) ).
Although he repeatedly denied it, much of the purport of Dr. Brautbar's testimony was that, because he found there to have been an effect on Mr. Walsh's chromosomes that in his judgment could only be attributed to benzene or pesticides, Mr. Walsh must have experienced a sufficient dose from the defendants’ pesticides to have caused it. See, e.g. , N.B. at 511-512. As Appellants explain at length, this represents another example of circularity in Dr. Brautbaur's reasoning. See, e.g. , Joint Brief for Appellants Bayer CropScience LP, Bayer Corp., Bayer CropScience Holding Inc. & Dow Agrosciences LLC at 28.
Critically, this restriction "applies to an expert's methods, not his conclusions." Grady v. Frito-Lay, Inc. , 576 Pa. 546, 839 A.2d 1038, 1047 (2003) ; accord Maj. Op. at 456 ("While the methodologies employed by the expert must be generally accepted, the conclusions reached from those applications need not also be generally accepted."). The Frye court itself explained:
Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.
Frye , 293 F. at 1014 (emphasis added).
While we can agree with the United States Supreme Court that, in assessing the admissibility of an expert's testimony, a court should not turn a blind eye when an expert connects his method to his conclusion only by the because-I-said-so of his "ipse dixit ," Gen. Elec. Co. v. Joiner , 522 U.S. 136, 146, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997), the Frye standard provides the complementary restriction that the court may not rely upon its own ex cathedra appraisal of the expert's methods to exclude such evidence. The balance is struck by requiring the court to rule based solely upon its assessment of the evidence and argument submitted by the parties to establish or contradict such acceptance. See Grady , 839 A.2d at 1045 ("[R]equiring judges to pay deference to the conclusions of those who are in the best position to evaluate the merits of scientific theory and technique when ruling on the admissibility of scientific proof, as the Frye test requires, is the better way of [e]nsuring that only reliable expert scientific evidence is admitted at trial."). How effectively and convincingly an expert employs a given methodology is a matter for the jury to assess. Our belief in the importance of the methods/conclusions distinction animates this Court's continued adherence to Frye . In a passage often cited by this Court, the United States Court of Appeals for the District of Columbia Circuit explained:
The requirement of general acceptance in the scientific community assures that those most qualified to assess the general validity of a scientific method will have the determinative voice. Additionally, the Frye test protects [both parties] by assuring that a minimal reserve of experts exists who can critically examine the validity of a scientific determination in a particular case. Since scientific proof may in some instances assume a posture of mystic infallibility in the eyes of a jury of laymen, the ability to produce rebuttal experts, equally conversant with the mechanics and methods of a particular technique, may prove to be essential.
United States v. Addison , 498 F.2d 741, 744-45 (D.C. Cir. 1974) ; see Commonwealth v. Dengler , 586 Pa. 54, 890 A.2d 372, 381 (2005) (quoting Addison ); Commonwealth v. Topa , 471 Pa. 223, 369 A.2d 1277, 1282 (1977) (same).
Simply put, the trial court should ensure that a "renegade researcher" does not appear before the jury robed in the implicit authority of an expertise that his or her methodology calls into question. But once the court determines, with the assistance of the proponent's proofs and the accounts of fellow experts in the discipline, that the analysis proceeds from generally accepted principles and methods, the court may proceed no further. Questions concerning the quality and persuasiveness of the applications and conclusions must be resolved by the collective judgment of the jury. Aided by the crucible of the parties’ adversarial presentations, the jury is just as capable as the average judge of weighing the parties’ competing accounts, identifying and rejecting particular applications of generally accepted principles and methods that either depart from standard practice in the field or lack a sufficient evidentiary foundation.
Daubert jurisdictions generally grant trial courts substantially broader discretion to stop expert testimony at the courtroom door. Federal Rule of Evidence 702 provides:
In the interim between the enactment of Rule 702 in 1975 and the Daubert decision in 1993, the advent of toxic tort litigation engendered concerns about the overly permissive admission of what some have called "junk science." During that spell, courts applied increasingly disparate principles to determine the admissibility of expert evidence. According to one commentator, "[b]y 1993, the year of Daubert , ‘the Supreme Court got the message: [s]omething needed to be done.’ " Jim Hilbert, The Disappointing History of Science in the Courtroom: Frye, Daubert, and the Ongoing Crisis of "Junk Science" in Criminal Trials , 71 Okla. L. Rev. 759, 779 (2019) (quoting Barbara Pfeffer Billauer, Daubert Debunked: A History of Legal Retrogression and the Need to Reassess "Scientific Admissibility," 21 Suffolk J. Trial & App. Advoc. 1, 27 (2015-16) ).
There is also ample evidentiary support for Judge Wettick's rejection of Dr. Brautbar's "fingerprints" theory, as lacking any grounding in appropriate scientific methodology. For example, and as the majority recognizes, a defense expert testified, consistent with Judge Wettick's opinion, that this theory is wholly unsupported by the scientific literature. See Deposition of Marshall Lichtman, M.D., dated December 18, 2015, at 33-34 ("I did not see any accepted methodology and I could not find any support for the statement in the material that Dr. Brautbar used to arrive at his opinions."); id. at 35; id. at 45 (explaining that "there is [scientific] agreement that there is no cytogenetic pattern that can allow you to determine if a patient was exposed to a chemical that might have played a role in causing their case of acute myelogenous leukemia" (emphasis added)); id. at 49-50 ("That's a novel concept and, as far as I can tell, it's pulled out of the air."); id. at 76; accord Deposition of Michael I. Greenberg, M.D., dated Jan. 15, 2016, at 42-43 (reiterating that there is no support in the published literature for Dr. Brautbar's "fingerprints" opinion).
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.
F.R.E. 702. Subparagraphs (b) and (d) have no counterpart in Pennsylvania's corresponding rule, and it is there that the "gatekeeping" mandate in its strongest sense lives.
The Court observed that Rule 702 "displaced" the Frye test. Daubert , 509 U.S. at 589, 113 S.Ct. 2786 ; accord Joiner , 522 U.S. at 142, 118 S.Ct. 512.
As reflected above, I respectfully disagree with the majority's pronouncement that Dr. Brautbar's analysis was free from extrapolation in relevant regards. See Majority Opinion, at 463. Indeed, it is very difficult to understand Dr. Brautbar's testimony as anything else besides extrapolation from a class to particular products when he had no idea of the dose-response threshold associated with any specific product, see e.g. , N.B. at 798, nor any appreciation of the dose experienced by Mr. Walsh for any product, see, e.g. , id. at 300-301, 552, 798.
Dr. Zambelli-Weiner also extrapolated severely, since her opinion that pesticides as a class cause leukemia, see, e.g. , Deposition of April Zambelli-Weiner, Ph.D., dated Sept. 23, 2014, at 74, can only be understood to apply to Appellees’ discrete products since they are pesticides, accord id. at 105 (reflecting Dr. Zambelli-Weiner's explanation that her opinions "are related to pesticides as a class" and "to the extent that a product is a pesticide, it is included in that opinion"). And I agree with Judge Wettick that such a gross form of extrapolation lacks any basis in accepted scientific methodology. See Walsh , No. GD-10-018588, slip op. at 19 (C.P. Allegheny Oct. 16, 2016).
Interestingly, the Daubert Court evidently deemed it necessary, or at least beneficial, to address concerns that its interpretation of Rule 702 would loosen the standard for admissibility relative to the Frye test, rather than empowering judges to guard the courtroom more stringently than Frye allowed. Thus, while it underscored the Federal Rules’ of Evidence "approach of relaxing the traditional barriers to ‘opinion’ testimony," and emphatically disagreed that Rule 702 implicitly preserved Frye ’s "austere" general acceptance requirement, the Court commented that Frye ’s displacement "[did] not mean ... that the Rules themselves place no limits on the admissibility of purportedly scientific evidence." Daubert , 509 U.S. at 588-89, 113 S.Ct. 2786.
In keeping with this expectation, in a passage I embrace even though I reject the rule it was formulated to support, the Daubert Court persuasively explained why courts should apply a more permissive rather than unduly strict standard. In rejecting concerns that abandoning the "general acceptance" criterion as such would leave "befuddled juries ... confounded by absurd and irrational pseudoscientific assertions," the Daubert Court deemed the argument "overly pessimistic about the capabilities of the jury and of the adversary system generally. 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 595-96, 113 S.Ct. 2786.
Even several years later, the Joiner Court professed to believe that the Daubert standard was more permissive in favor of the admission of expert evidence than the Frye standard. See Joiner , 522 U.S. at 142, 118 S.Ct. 512 ("[W]hile the Federal Rules of Evidence allow district courts to admit a somewhat broader range of scientific testimony than would have been admissible under Frye , they leave in place the ‘gatekeeper’ role of the trial judge in screening such evidence." ). But in dismissing the Frye -based argument that the court may consider only the general acceptance of methods while avoiding the reasoning overlain upon that methodological foundation, the Court ensured otherwise, explaining:
The Majority and Chief Justice Saylor disagree over the pertinence of the "gatekeeping" terminology endemic to the law concerning the admissibility of evidence in both Frye and Daubert jurisdictions. Compare Maj. Op. at 458 ("Whether we refer to the role of the trial court in a Frye contest as that of a "gatekeeper" is not consequential."), with Diss. Op. at 476–77 (noting that gatekeeping "is the clear purport of most of this Court's decisions on the subject"). As the quotation from Joiner makes clear, the gatekeeper terminology is a commonplace in both Frye and Daubert case law. Moreover, it is not inapt to say that the trial court acts as a gatekeeper in determining the admissibility of evidence generally. Nonetheless, I generally avoid the gatekeeper terminology, because at least colloquially it suggests a more jealously guarded portal than the Frye test calls for.
The "conventional fashion" language taken from Betz was also used in this manner in each of the remaining decisions and responsive opinions in this Court cited by the concurrence. See Mitchell v. Shikora , ––– Pa. ––––, –––– n.12, 209 A.3d 307, 319 n.12 (2019) ; Commonwealth v. Walker , 625 Pa. 450, 489, 92 A.3d 766, 790 (2014) ; Commonwealth v. Treiber , 632 Pa. 449, 538, 121 A.3d 435, 488 (2015) (Saylor, C.J., dissenting).
Parenthetically, the majority opinion in Jacoby does manifest an idiosyncrasy in its own right, since it characterizes unconventionality in methodology as the exclusive measure for novelty. See Jacoby , 642 Pa. at 667, 170 A.3d at 1091. On the novelty issue, however, Betz only decided the issue that was before the Courti.e. , whether the concept of novelty subsumed generally-accepted methodology applied in an unconventional fashion. There should never have been any doubt that Frye also extends to "novel science" -- for example, a new scientific test for truth-telling -- in the first instance. See Betz , 615 Pa. at 545, 44 A.3d at 53 (citing Grady , 576 Pa. at 557, 839 A.2d at 1045 ).
[C]onclusions and methodology are not entirely distinct from one another. Trained experts commonly extrapolate from existing data. But nothing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence that 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 . at 146, 118 S.Ct. 512.
Daubert ’s and Joiner ’s protestations soon proved unwarranted. As Professor Bernstein observed less than a decade after the decision issued, " Daubert , particularly as extended by Joiner and Kumho Tire ,[ ] ha[d] become a far broader and stricter test than Frye ever was." David E. Bernstein, Frye, Frye, Again: The Past, Present, and Future of the General Acceptance Test , 41 JURIMETRICS . J. 385, 404 (2001) (hereinafter "Frye, Frye, Again "); cf. Hilbert, supra n.5, at 791-92 (noting continuing dispute about whether Daubert in fact increased the frequency with which expert evidence was excluded in federal courts).
See Kumho Tire Co., Ltd. v. Carmichael , 526 U.S. 137, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999). The Court in Kumho Tire extended application of the Daubert test to all expert testimony, not just "scientific" testimony. See id. at 141, 119 S.Ct. 1167.
In this regard, the issue was raised and developed -- and discussed extensively -- by the parties and their amici . Compare Betz , 615 Pa. at 530-31, 44 A.3d at 43-44 (reflecting that the defendant-appellants contended that a Frye hearing was warranted because, while the challenged expert "ostensibly accepted the applicability of" conventional scientific methodology, his opinion "in substance, nevertheless disregards this elemental precept in its entirety"), with id. at 542-43, 44 A.3d at 51 (summarizing the plaintiff-appellees’ argument that there was "no justification for conducting a Frye hearing," since their expert's methodology was "utterly mainstream").
To some extent, the tension between the Court's stated impression that Frye was more stringent than Daubert and the fact that Daubert emerged as the stricter test of the two may be explained by differences in the forms each takes in various jurisdictions. Merely citing Frye or Daubert as the governing standard furnishes no assurance of consistency of application. See generally Frye, Frye, Again , 41 JURIMETRICS . J. at 397-98 (observing that Frye jurisdictions were ruling inconsistently on the question of whether a court may only examine methodology for general acceptance or also consider the relative acceptance of the expert's conclusions). More recently, one commentator counted twenty-five states that have a rule of evidence that mirrors Federal Rule 702 and purport to follow Daubert , fifteen states that apply Frye in more or less its original form, another half-dozen states that do not reject Frye outright but apply Daubert factors in practice, and four states that follow a test somewhat of their own devising. See Samuel D. Hatch, Where Are the Gatekeepers? Challenging Utah's Threshold Standard for Admissibility of Expert Witness Testimony , 2018 UTAH L. REV. 1123, 1140 (2018). And as far back as 2001, Professor Bernstein observed what he identified as a convergence in practice of the Frye and Daubert tests. See Frye, Frye, Again , 41 JURIMETRICS J. at 385.
Regardless, in my view what the Daubert Court characterized as Frye ’s "austerity" manifests in Pennsylvania practice not in an overly exclusionary effect, but rather in its assurance that the trial court does not adopt too expansive a view of its important but limited role in ensuring that only qualified expert evidence reaches a jury. And it should surprise no one that a test that asks only whether a given "expert's methodology is generally accepted in the relevant field," Pa.R.E. 702(c), will result in the admission of more evidence than one that requires the court to assess whether the expert's "principles and methods" are "reliable" (a criterion I read as similar in practice to general acceptance), and determine for itself whether the "testimony is based on sufficient facts or data," and assess whether "the expert has reliably applied the principles and methods to the facts." F.R.E. 702 (emphasis added).
As though that were not enough, the Daubert Court cited four additional considerations as relevant: (1) whether the theory or technique at issue "can be (and has been) tested"; (2) "whether the theory or technique has been subjected to peer review and publication"; (3) "in the case of a particular scientific technique, ... the known or potential rate of error ... and the existence and maintenance of standards controlling the technique's operation"; and (4) "general acceptance," because "[w]idespread acceptance can be an important factor in ruling particular evidence admissible, and a known technique which has been able to attract only minimal support within the community may properly be viewed with skepticism." Daubert , 509 U.S. at 593-94, 113 S.Ct. 2786 (cleaned up). In theory, each factor presents a distinct basis for exclusion, and thus each factor, too, exponentially increases the likelihood of inconsistent application.
Later, the Court observed:
[W]e can neither rule out, nor rule in, for all cases and for all time the applicability of the factors mentioned in Daubert , nor can we now do so for subsets of cases categorized by category of expert or by kind of evidence. Too much depends upon the particular circumstances of the particular case at issue.
Kumho Tire, 526 U.S. at 150, 119 S.Ct. 1167 ; see id. at 151, 119 S.Ct. 1167 ("[Daubert ] made clear that its list of factors was meant to be helpful, not definitive."). Highlighting just one potential concern, Professor Hilbert notes "profound disparities in how Daubert has been applied, both between civil and criminal contexts, and between parties in each context," including "a double standard" favoring respectively civil defendants and prosecutors. See Hilbert, supra n.5, at 796.
Betz relates that Pennsylvania courts tend to downplay access to other rule-based tools for trial judges to screen scientific evidence, such as the ability to refuse to admit evidence to avoid unfair prejudice, confusion of the issues, or misleading the jury. See Betz , 615 Pa. at 544, 44 A.3d at 52 (citing Pa.R.E. 403, as well as the helpfulness consideration of Rule of Evidence 702). This, of course, tends to elevate the importance of appropriate screening under Frye. Additionally, the Court reasoned as follows:
Various reasons underlie the preference to limit the courts' involvement in determining the admissibility of scientific evidence. There is the concern that liberality in allowing challenges would substantially increase the number of challenges (and cases in which lengthy pre-trial proceedings would ensue). The competency of trial judges to accept or reject scientific theories remains a legitimate subject of controversy. Additionally, a claim or defense in many cases may rise or fall based upon expert testimony and, therefore, there is some reluctance on the part of courts to deprive litigants of their day in court.
On the other hand, this Court has recognized the influential nature of expert testimony on complex subjects, and the potential that distortions have to mislead laypersons. See [Grady , 576 Pa.] at 558, 839 A.2d at 1045 ; Topa, 471 Pa. at 231–33, 369 A.2d at 1281–82. It would be naïve, in this regard, to assume that the possibility for distortion is limited to the very newest realms of science. Cf. Grady, 576 Pa. at 557, 839 A.2d at 1045 (explaining that Frye applies not only to novel science, but also where scientific methods are utilized in a novel way).
We therefore agree with Appellants that a reasonably broad meaning should be ascribed to the term "novel."
Betz , 615 Pa. at 545, 44 A.3d at 53.
With thirty or more states applying Daubert , Pennsylvania remains a Frye stalwart. In Grady , we expressed clearly why we prefer Frye :
One of the primary reasons we embraced the Frye test in Topa was its assurance that judges would be guided by scientists when assessing the reliability of a scientific method. Given the ever-increasing complexity of scientific advances, this assurance is at least as compelling today as it was in 1977, when we decided that case. We believe now, as we did then, that requiring judges to pay deference to the conclusions of those who are in the best position to evaluate the merits of scientific theory and technique when ruling on the admissibility of scientific proof, as the Frye rule requires, is the better way of [e]nsuring that only reliable expert scientific evidence is admitted at trial.
We also believe that the Frye test, which is premised on a rule—that of "general acceptance"—is more likely to yield uniform, objective, and predictable results among the courts, than is the application of the Daubert standard, which calls for a balancing of several factors. Moreover, the decisions of individual judges, whose backgrounds in science may vary widely, will be similarly guided by the consensus that exists in the scientific community on such matters.
Grady , 839 A.2d at 1044-45.
In Betz , however, our fidelity to these principles was undermined in a subtle but potentially important manner. Specifically, Betz introduced into Pennsylvania law a "conventionality" requirement, suggesting that expert testimony in a scientific discipline is admissible only when the expert has "applied accepted scientific methodology in a conventional fashion in reaching his or her conclusions." Betz , 44 A.3d at 53 (emphasis added). This conventional application requirement, however, cannot be found in Topa , Grady , or the Pennsylvania Frye cases that followed, and it sounds very much like Federal Rule 702 ’s direction that the court assess whether "the expert has reliably applied the principles and methods to the facts of the case." F.R.E. 702(d) (emphasis added). This at least gestures toward the more probing, credibility-inflected Daubert inquiry, which we squarely rejected in Grady . I fear that Betz ’ conventional application overlay purports or operates to require a court to assess something beyond the general acceptance of a given expert's methods.
I can find in Pennsylvania law no pre- Betz source for the conventional application formulation. But this Court has recycled Betz ’ language on numerous occasions since then. See Mitchell v. Shikora , ––– Pa. ––––, 209 A.3d 307, 319 n.12 (2019) ; Commonwealth v. Jacoby , 642 Pa. 623, 170 A.3d 1065, 1090-91 (2017) ; Commonwealth v. Walker , 625 Pa. 450, 92 A.3d 766, 790 (2014) ; see also Commonwealth v. Treiber , 632 Pa. 449, 121 A.3d 435, 488 (2015) (Saylor, C.J., dissenting). I believe that repeating Betz ’ Daubert -esque language can only erode this Court's commitment to Frye ’s narrow focus upon the expert's underlying principles and methodology.
As my authorship in Jacoby attests, I am not blameless in uncritically repeating Betz’ formulation.
In this regard, since unscientific methodology is also unconventional, there is a great deal of overlap between the terms. And I would submit that the greater range of cases in which scientific evidence is excluded, as this one, address evidence that is both unconventional and unscientific. See supra note 2.
Certainly, the substantive Frye test shouldn't be applied so stringently as to absolutely forbid scientific methodology applied in a unique way, so long as the new manner itself can reasonably be viewed as scientific (or as being sufficiently grounded in generally-accepted principles). This is why the Betz Court chose the "unconventional" litmus solely to identify situations where the courts should take a close look (i.e. , conduct a Frye hearing) to screen against unscientific lapses in the methodology, such as analytical gaps and abstractions.
As related above and below, the particular strain of "unconventionality" embedded in Dr. Brautbar's opinionsi.e. material analytical gaps and abstractions -- is and should be excluded from courtrooms. See infra .
The Superior Court has followed our lead in precedential opinions, including in this case, see Walsh v. BASF Corp. , 191 A.3d 838, 844 (Pa. Super. 2018) ; Commonwealth v. Nevels , 203 A.3d 229, 237-38 (Pa. Super. 2019) ; Commonwealth v. Freeman , 128 A.3d 1231, 1246 (Pa. Super. 2015), and in several non-precedential memoranda.
As a separate matter, during the course of his critique of Betz , without citation, Justice Wecht restates the holding as follows:
In Betz , ... the Court appeared to hold, and unquestionably implied, that when an expert testifies that any exposure to a toxic substance enhances the risk that the exposed party will suffer injury as a consequence of that particular exposure, the expert inadmissibly suggests that the exposure in question, even when de minimis , is a substantial cause of the injury.
Concurring Opinion, at 474. In Betz , however, there simply was no reason for the Court to infer anything about substantial-factor causation from discussions by the challenged expert about increased risk in the abstract. Rather, the case concerned the challenged expert's explicit opinion that was offered as the sole evidence to address the plaintiff-appellees’ burden to prove substantial-factor causation. In this regard, the specific opinion at issue was that de minimus exposurei.e. , breathing a single asbestos fiber from a defendant's product -- was a substantial factor in causing any given instance of asbestos-related disease in any individual who was so exposed. See Betz , 615 Pa. at 510, 44 A.3d at 31.
Along these lines, I find the concurrence's assertion that Rost appropriately overruled the above rationale attributed to Betz to be equally misplaced. See Concurring Opinion, at 474–75.
I have acknowledged nonetheless, that the majority decision in Rost did work a distinct retrenchment relative to Betz , at least insofar as concerns asbestos-mesothelioma cases. See supra note 2.
Chief Justice Saylor is correct that in Betz , as in this Court's cases that have quoted its formulation since, the conventional application terminology was used narrowly as a basis to identify novel science for purposes of determining whether to conduct a Frye inquiry in the first instance. But I disagree that Daubert -esque terminology presents no risk of "confusi[on], at all." Diss. Op. at 482. To confirm that the Chief Justice's optimism is misplaced, one need look no further than the sentence that introduces Appellants’ brief in this case: "Recognizing that any causation opinion must be premised on a generally accepted methodology applied in a conventional fashion , [the trial court] excluded Plaintiff's experts for failing to meet Pennsylvania's Frye standard." Appellants’ Brief at 1. Appellants later add that "[a]ny methodology, even if generally accepted , must be applied ‘in a conventional fashion’ to satisfy Frye ." Appellants’ Reply Brief at 12 (quoting Betz , 44 A.3d at 53 ) (emphasis added). These "conventionality" usages do not recognize or embody the Dissent's proffered limitation, especially given the pervasiveness of their recurrences with and without citation to Betz . See , e.g. , Appellant's Brief at 21 (citing Betz , incorrectly by the Majority's lights), 34 (same), 35 (ascribing the conventional application requirement to Blum , supra ) ; see also Appellants’ Reply Brief at 5, 8 (ascribing the conventional application requirement to Mitchell , supra ). In its published decision, the court below manifested precisely the same confusion. See Walsh , 191 A.3d at 844 ("Frye requires that a proponent of novel scientific testimony demonstrate that the expert relied upon and conventionally applied a scientific method generally accepted in the relevant scientific community.").
The notion of bright lines in the Frye approach has always been somewhat fanciful. The Frye court observed that, "while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs." Frye , 293 F. at 1014. But reading Frye and Betz in tandem, to find this enterprise as straightforward as the Dissent suggests it is or should be, we would need to clearly distinguish the "application" of a given principle (relevant to whether to conduct a Frye inquiry in the first instance) from the expert's "deduction" from that principle (relevant to whether the deduction passes Frye test), which strikes me as a quixotic aspiration. Courts seeking tidiness and clarity will search the Frye /Daubert morass in vain; all we can hope to do is avoid excess confusion where possible.
The conventional application requirement encourages litigation tactics familiar to Daubert jurisdictions and rewarded by the trial court in this case. In denying the admission of all causation testimony, the trial court all but erased the defining distinction between Frye and Daubert . Although the trial court did not cite Betz ’ formulation of the Frye standard, the court's detailed review of the many studies and sources cited by Nachman Brautbar, M.D., was replete with the court's own disagreements regarding the application of the methods and data delineated in the studies themselves. Nowhere in the court's two supporting opinions did it rely substantially upon the expert evidence that Defendants adduced to challenge the general acceptance of Plaintiff's experts’ methods. Thus, we have no reason to believe that the trial court was persuaded by Defendants’ Frye evidence rather than by its own unbounded frolic through the literature.
In this regard, the Chief Justice seeks both to validate this aspect of the trial court's approach and to buttress it with a handful of references to Defendants’ countervailing Frye evidence. See Diss. Op. at 477–82. But the trial court never cited anything but its own independent survey of Plaintiff's expert evidence as a basis for excluding that evidence. This calls into question the degree to which the trial court concerned itself with the competing evidentiary showings on general acceptance, and it is not an appellate court's function to fill that critical void in the trial court's account of its own reasoning. Furthermore, I disagree with the Dissent's suggestion that constraining the court to consider only the parties’ competing presentations regarding general acceptance "imposes an unreasonable constraint on the trial courts’ ability to perform the essential review for reliability." Id . at 480. The very invocation of a trial court assessment of "reliability" hearkens back to the Federal Rule and Daubert considerations, and what concerns me is precisely the risk of that sort of Daubert -ization of our Frye standard. Nothing about our law to date precludes a trial court from looking to the documentation submitted in support of a given scientific method. But the court's review must be channeled by the adversarial presentations of the parties’ Frye experts, not limited only by the scope of the trial court's intellectual ambition and willingness to pursue the matter independently.
To the extent that the trial court acknowledged the methods/application argument at all, it did so only by dispatching a strawman. The court unfairly reduced Plaintiff's position to the proposition that the mere introduction of any literature, no matter how inapt, takes the admissibility determination from the court's hands. According to the trial court's account of Plaintiff's argument, "Dr. Brautbar may cite a study regarding traffic patterns in New York City for the proposition that Chemical A causes [disease] in humans." Tr. Ct. Supp. Memo., 12/27/2016, at 6. But the specter of a court powerless to exclude evidence once any literature is introduced, however irrelevant, is absurd on its face; one need not plumb the depths of that literature to discern patent irrelevance. Indeed, if such irrelevance were at issue here, the trial court's opinion would not be so voluminous in characterizing and parsing and finding wanting or inapplicable Dr. Brautbar's supporting materials. Some of our Commonwealth's fine trial judges may well have the wisdom of Solomon; certainly we aspire. But even Solomon did not have a medical degree or a doctorate, and wisdom is no substitute for subject matter expertise. A trial court should not deny a litigant the benefit of a chosen expert because, after the court's unilateral and "intensely granular" screening, see Maj. Op. at 460 n.9, something about the sources upon which the expert relies triggers the court's doubt. Our judges are appointed or elected from the ranks of lawyers whose knowledge and experience span the gamut of legal specialties, but seldom involve ever-increasingly esoteric areas of technical and scientific inquiry. In our adversarial system, judges are generalists, whom we ask to manage, but not to drive, jury trials. In France's inquisitorial system, jurists are selected to undergo a rigorous, multi-year training program, culminating for some in the completion of a thirty-one-month course of study in legal topics as well as sociology, psychology, psychiatry, forensic science, pathology, and accounting, which is in keeping with the greater degree to which French judges actively participate in the truth-determining process. But this is not France.
The Chief Justice pummels the same strawman when he presents the false choice between "permitting trial courts to consider whether experts actually adhere to the methodology that they only facially espouse" or "accept[ing] the sort of expert self-validation which is of great concern to most courts." Diss. Op. at 483. By no means do I believe, nor would I hold, that a court cannot identify and discard inferences and conclusions wholly divorced from their purported basis. Rather, I merely underscore the proposition, long-embraced by this Court, that trial courts should exercise considerable restraint in doing so. They do so foremost by focusing upon the Frye evidence adduced by the parties rather than deputizing themselves—as the trial court did in this case—to do the sort of sua sponte deep dive into the literature that the trial court performed in this case. Cf. Maj. Op. at 458 ("The trial court may consider only whether the expert applied methodologies generally accepted in the relevant field, and may not go further to attempt to determine whether it agrees with the expert's application of those methodologies or whether the expert's conclusions have sufficient factual support. Those are questions for the jury to decide." (footnote omitted)). Trial courts further advance this principle in close cases by erring in favor of admitting the contested evidence.
See Kelly Buchanan, The French National School for the Judiciary , In Custodia Legis: Law Librarians of Congress (Jan. 26, 2011), https://blogs.loc.gov/law/2011/01/the-french-national-school-for-the-judiciary/.
Our necessary reliance upon judges who lack the expertise to determine what evidence should reach a jury creates certain risks that are exacerbated by the Daubert standard. Thus, commentators have expressed reservations about jurists’ ability to apply Daubert consistently, noting, for example, that " Daubert places a greater epistemic burden [than Frye ] on judges tasked with determining the reliability of proposed expert testimony." James R. Dillon, Expertise on Trial , 19 COLUM. SCI . & TECH. L. REV . 247, 262 (2018). Indeed, Prof. Steiner-Dillon submits "that judges generally cannot apply the Daubert test with a level of competence necessary to satisfy intellectual due process." Id. at 272. By contrast, "[t]he Frye test delegates the question of reliability to a community of recognized experts. The court's task consists only in identifying the relevant community and determining whether it generally accepts the methodology at issue." Id . at 260. Anticipating this concern, Chief Justice Rehnquist commented in Daubert : "I do not doubt that Rule 702 confides to the judge some gatekeeping responsibility in deciding questions of the admissibility of proffered expert testimony. But I do not think it imposes on them either the obligation or the authority to become amateur scientists in order to perform that role." Daubert , 509 U.S. at 600-01, 113 S.Ct. 2786 (Rehnquist, C.J., concurring in part and dissenting in part). In keeping with Frye , I would relieve trial courts of the burden of trying.
A doctoral candidate when he published the cited article, Prof. Steiner-Dillon, née Dillon, joined the faculty of the University of Dayton School of Law in 2018, the same year the article appeared.
Professor Steiner-Dillon notes that Frye is not without its own difficulties:
[T]he knottiest problem posed by Frye is the definition of the relevant community: if the reliability inquiry is a matter of nose counting, whose noses are to be counted? This is a problem of great practical import because domains or sub-disciplines often have disciplinary axioms and epistemic norms that lead them to view the reliability of a particular methodology quite differently. Closely related to the problem of identifying the relevant community is the problem of identifying its boundaries. Should the community be defined broadly or narrowly? As Cole and Edmond observe, "[c]ontestation over whether the [reference community] should be construed narrowly or broadly is endemic to a Frye analysis. ... [N]arrow interpretations tend to favor proponents of contested evidence whereas broad interpretations tend to favor opponents and exclusion."
Dillon, 19 Colum. Sci. & Tech. L. Rev . at 262 (footnotes omitted) (quoting Simon A. Cole & Gary Edmond, Science without Precedent: The Impact of the National Research Council Report on the Admissibility and Use of Forensic Science Evidence in the United States , 4 BRIT. J. AM. LEGAL STUD . 586, 606 (2015)).
The Chief Justice observes that Prof. Steiner-Dillon expresses similar concerns regarding the ability of jurors to digest scientific evidence. Diss. Op. at 485. He further notes that Prof. Steiner-Dillon proposes that courts appoint a sort of scientific ombudsman to take on the expert evidence screening function and conduct independent research, measures more consistent with the inquisitorial system noted above than with our adversarial system, flawed though it may be. Id. at 485–86; cf. Gerald Walpin, America's Adversarial & Jury Systems: More Likely to Do Justice , 26 Harv. J. Law & Pub. Policy 175, 175-76 (2003) (observing, pace Winston Churchill, that "the adversarial system may be the worst form of judicial procedure except for all others than have been tried from time to time"). But that he identifies similar infirmities in both judges and juries attempting to assess the credibility and merit of expert presentations does not detract from my view that, when in doubt, we must trust juries to glean the more convincing expert account through our time-honored adversarial process.
Betz and this Court's subsequent, related decision in Rost v. Ford Motor Co. , 637 Pa. 625, 151 A.3d 1032 (2016), are most notable for their contribution to the law governing the use and effect of "any exposure" causation testimony in toxic torts, and with respect to asbestos specifically. In Betz , applying the above-reproduced standard, the Court appeared to hold, and unquestionably implied, that when an expert testifies that any exposure to a toxic substance enhances the risk that the exposed party will suffer injury as a consequence of that particular exposure, the expert inadmissibly suggests that the exposure in question, even when de minimis , is a substantial cause of the injury. In Rost , this Court carefully limited that holding, observing that it applied only where the expert in question rested its opinion regarding substantial causation entirely on that de minimis exposure in reliance upon the any-exposure theory. Conversely, where an expert testifies to that theory, which is not controversial as a general principle, but also testifies that the plaintiff's exposure to a given toxic substance was greater than de minimis and substantially causative based upon an individualized application of the frequency, regularity, and proximity test, the testimony suffices to create a jury question regarding substantial causation. Thus, Rost served as a bulwark against the potential for overbroad application of Betz ’ very narrow ruling. In effect, Rost solidified what was best from Betz and distanced the Court from an unduly broad understanding of what remained.
See Diss. Op. at 478 n.2 (noting that Rost has yet to be applied outside the asbestos context).
See generally Gregg v. V-J Auto Parts, Co. , 596 Pa. 274, 943 A.2d 216 (2007).
I fail to see how anything in this discussion indicates that I view Rost as overruling Betz , or even deviates much from the Chief Justice's previously-stated view. See Diss. Op. at 483–84 n.11; cf. Rost , 151 A.3d at 1057 (Saylor, C.J., dissenting) (characterizing the Majority as "cabin[ing]" Betz ). I simply believe that Betz ’ utility is substantially diminished in the wake of Rost , which Chief Justice Saylor accurately observes "work[ed] a distinct retrenchment relative to Betz ." Diss. Op. at 483–84, n.11. I further believe that Betz ’ jurisprudential value is substantially undermined by its introduction of the "conventional application" formulation.
The only distinctive, indeed singular, aspect of Betz that remains—the only thing in Betz that cannot be conveyed more effectively by citing Rost —is the "conventional application" language, which threatens to smuggle Daubert ’s more expansive ideas about judges’ role in determining the admissibility of expert evidence into Pennsylvania law. Among the most worrisome potential effects of Betz ’ conventional application requirement is that it casts into doubt the proponent's ability to bring rigorous scientific innovation to the matter, leaving the law—and more importantly jurors—behind as science passes it by. Thus, our law has retained Frye ’s focus upon the general acceptance of the theory or technique underlying expert testimony, rather than how or what an expert extrapolates from it, keeping the door open to innovative applications of accepted principles and methodologies.
While the point may seem finely drawn, when we hold the line at conventional application, we suggest that there is no more room for novelty than an expert venturing a novel final opinion or conclusion, and even that only if the expert arrived there using entirely "conventional" means—all as assessed by a judge who, more likely than not, is not conversant enough in the relevant discipline to confidently opine on conventionality at all. Because I do not agree that it is jurisprudentially sound or consistent with Pennsylvania law to risk usurping the role of the jury by overzealous application of Betz ’ "conventional application" criterion, I believe that this terminology unnecessarily complicates Pennsylvania's Frye jurisprudence and should be avoided in this and future Frye cases.
Even the Kumho Tire Court recognized a species of this concern, noting that "[i]t might not be surprising in a particular case, for example, that a claim made by a scientific witness has never been the subject of peer review, for the particular application at issue may never previously have interested any scientist." Kumho Tire , 526 U.S. at 151, 119 S.Ct. 1167.
As the Majority explains, the trial court wandered far afield of interrogating Dr. Brautbar's methods, clearly rendering its own sua sponte judgment with regard to the worth of the studies Dr. Brautbar cited in support of his methods and conclusions, as well as its apparently independent judgments as to abstruse questions concerning the postulates, inferences, and conclusions Dr. Brautbar gleaned from these numerous sources and the record in this case. In doing so, the court did far more than rely solely upon the competing accounts provided by the parties’ experts, and so it exceeded the bounds of its discretion. Accordingly, I join the Majority's analysis.
CONCURRING AND DISSENTING OPINION
JUSTICE BAER
I join the majority opinion as to Issues One and Three, subject to the clarifications set forth below. I likewise agree with the majority's mandate, remanding the case to the trial court to afford Appellants the opportunity to reassert their challenges to Appellee's expert scientific evidence pursuant to Frye v. United States , 293 F. 1013 (D.C. Cir. 1923). I respectfully dissent, however, from Issue Two, as I agree that Appellee's experts engaged in improper extrapolation for the reasons ably set forth by the Chief Justice in his dissenting opinion.
While I join the majority as to Issue One, I write separately to express my view that this case involves closer questions as to whether the trial court abused its discretion, given the analytical gaps identified by the trial court that call into question the methodology employed by Appellee's experts, as summarized by the Chief Justice, see id. at 450–53. Indeed, some of these failings are also detailed in the majority's recitation of the Appellants’ experts’ testimony, see Majority Opinion, at 460–61.
Nevertheless, I ultimately agree with the majority that the trial court abused its discretion in concluding that Appellee's experts’ testimonies were inadmissible under Frye by utilizing its own assessment of the scientific evidence rather than specifically relying upon Appellants’ experts’ analysis. While a case may involve such a blatant failure of an expert to apply generally accepted methodologies that a trial court need not rely upon the opposing party's expert, trial courts in most cases should be guided by the experts offered by the parties rather than determining scientific validity on their own, especially considering the diversity of individual judges’ scientific knowledge. See Grady v. Frito-Lay, Inc. , 576 Pa. 546, 839 A.2d 1038, 1045 (2003) (recognizing the need for "individual judges, whose backgrounds in science may vary widely" to be "guided by the consensus that exists in the scientific community"). Indeed, the risk of trial courts assuming the role of scientific experts in determining what is "generally accepted" is more pronounced as the science becomes more complex, as demonstrated by the case at bar. Accordingly, I conclude that the trial court sub judice abused its discretion and remand is appropriate.
I additionally write to distance myself respectfully from the majority opinion to the extent it declines to recognize the trial court as "gatekeeper" in Frye challenges. Majority Opinion, at 458. As expressed by Judge Beck in Blum v. Merrell Dow Pharmaceuticals, Inc. , 705 A.2d 1314, 1325 (Pa. Super. 1997), aff'd , 564 Pa. 3, 764 A.2d 1 (2000), "the gatekeeping role of the court, far from detracting from the jury's function, is in fact essential to it [as it ensures] that what might appear to the jury to be science is not in fact speculation in disguise."
Finally, I join Part II of the Chief Justice's dissent, addressing this Court's prior decision in Betz v. Pneumo Abex LLC , 615 Pa. 504, 44 A.3d 27 (2012).
DISSENTING OPINION
CHIEF JUSTICE SAYLOR
The majority deems it inconsequential whether or not this Court should denominate trial judges as gatekeepers relative to the admission of novel scientific evidence in Pennsylvania courtrooms. See Majority Opinion, at 458. Personally, however, I find this to be the clear purport of most of this Court's decisions on the subject. My response to the majority opinion is set forth below. Since Justice Wecht has taken the opportunity, from a side position, to respond to my present remarks -- as well as to criticize the opinion that I authored in Betz v. Pneumo Abex LLC , 615 Pa. 504, 44 A.3d 27 (2012) -- I have also included my reply to his opinion.
I. Reply to the Majority Opinion
On an appropriate motion, trial judges in Pennsylvania bear the obligation to screen novel scientific evidence for reliability before permitting such evidence to be put before jurors. See, e.g. , Grady v. Frito-Lay, Inc. , 576 Pa. 546, 557, 839 A.2d 1038, 1044-45 (2003). This Court, like most others, has implemented this particular gatekeeping responsibility in light of the influential nature of expert testimony on complex subjects and the potential that distortions have to mislead laypersons. See Betz , 615 Pa. at 544-47, 44 A.3d at 52-54 ; see also id. at 532 n.15, 44 A.3d at 44 n.15 (quoting a cogent encapsulation by the Honorable Phyllis W. Beck in Blum v. Merrell Dow Pharms., Inc. , 705 A.2d 1314, 1325 (Pa. Super. 1997), aff'd , 564 Pa. 3, 764 A.2d 1 (Pa. 2000) ); accord In re Accutane Litig. , 234 N.J. 340, 191 A.3d 560, 589 (2018) (explaining that "the gatekeeping function prevents the jury's exposure to unsound science through the compelling voice of an expert" and "[d]ifficult as it may be, the gatekeeping role must be rigorous").
For these reasons, I have previously expressed the concern that the Frye standard should not be interposed in a way that deprives trial judges of the ability to screen expert opinions for sufficient reliability. See Commonwealth v. Smith , 606 Pa. 127, 186, 995 A.2d 1143, 1177 (2010) (Saylor, J., concurring and dissenting) ("[I]f the Court is going to interpret Frye so narrowly as to justify the admission of speculative opinions, or opinions falsely couched in scientific literature, I believe the time has come for Pennsylvania to move to the Daubert standard.").
In this regard, to the degree that the majority opinion advocates that the Frye standard is superior to approaches taken by other courts in the modern litigation environment, see, e.g. , Majority Opinion, at 456–57, I respectfully disassociate myself from that view. Accord Grady v. Frito-Lay, Inc. , 576 Pa. at 570, 839 A.2d at 1052 (Saylor, J., concurring) ("Concerning the Frye / Daubert debate, I take the position that the Frye rule is and remains the law of the Commonwealth, unless and until informed advocacy is presented that would favor a new direction, with due reference to the substantial body of information that has developed concerning the experience of the federal courts and others under Daubert ."). Significantly, I believe that there are benefits and drawbacks to each of the mainstream approaches, and I would reserve any assessment of the comparative merits to a setting in which the Court has the benefit of a developed analysis. See, e.g. , Accutane , 191 A.3d at 583-95 (reflecting the Supreme Court of New Jersey's recent refinement of the state's standard governing the admissibility of novel expert opinions, upon close consideration of the available options).
In my view, Judge Wettick properly discharged his gatekeeping function in the present case. Upon review of scientific literature relied upon by Dr. Brautbar, Judge Wettick found that there were extensive, unexplained analytical gaps between the expert's opinions and the material upon which he relied. See Walsh v. BASF Corp. , No. GD-10-018588, slip op. at 2-19 (C.P. Allegheny Oct. 16, 2016); see also Walsh v. BASF Corp. , No. GD-10-018588, slip op. at 2-6 (C.P. Allegheny Dec. 27, 2016). And that finding is amply supported by the record.
Indeed, the record support for Judge Wettick's conclusion includes the testimony of Dr. Brautbar himself. For example, Dr. Brautbar acknowledged that dose response is a fundamental tenet of toxicology. See, e.g. , See Deposition of Nachman Brautbar, M.D., dated May 15, 2014 at 836; accord Joseph V. Rodricks, Reference Guide on Exposure Science , REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 507 (Fed. Judicial Center 3d ed. 2011) ("Ultimately the dose incurred by populations or individuals is the measure needed by health experts to quantify the risk of toxicity.").1 He proceeded, however, to render opinions about substantial-factor causation relative to Mr. Walsh, while repeatedly conceding that he was both unable to identify any dose-response threshold for any of the fourteen products at issue in this case, see, e.g. , N.B. at 798, and that he had no idea of the quantity of the dose experienced by Mr. Walsh for any particular product, see, e.g. , id. at 300-301, 552. At least in many other courts, such testimony would plainly be regarded as unscientific and insufficient to establish substantial-factor causation.2
In this regard, Dr. Brautbar's notion of substantiality, in terms of the duration of exposure, doesn't conform at all to the legal standard, in that he defined the conception as merely being "not ridiculous, theoretical, or infinitesimal." Id. at 776. Furthermore, numerous defense experts highlighted the unscientific nature of Dr. Brautbar's analysis. See, e.g. , Deposition of Scott D. Phillips, M.D., dated Jan. 12, 2016, at 32 (reflecting the testimony of a medical toxicologist that Dr. Brautbar's methodology violated basic principles of toxicology in that he "simply stated that the dose was sufficient to cause his AML, which creates a circular logic reasoning kind of pathway"); Deposition of John Ross, Ph.D., dated Jan. 13, 2016, at 49 (remarking that Dr. Brautbar "repeated over and over again that it was the proximity, duration and frequency of exposure that allowed Mr. Walsh to be overexposed without providing a shred of evidence on what those were.").3 The circularity inherent in Dr. Brautbar's opinions is demonstrated throughout his deposition testimony. For example, after repeatedly asserting that the amount of exposure to each of the defendants’ products was substantial, the following interchange ensued between counsel for an appellant and Dr. Brautbar:
Q. [I]n terms of duration and the proximity and frequency, you don't know how much of the chemical -- the pesticide he was exposed to for the duration or for how close he was to it or how frequently?
A. No. I don't know.
* * *
Q. How -- how much [chlorothalonil] was Mr. Walsh exposed to during his work -- during his occupation?
A. He was exposed to a substantial dose, sufficient to contribute to his genotoxicity.
* * *
Q. But you can't tell me how much besides saying substantial?
A. Well, substantial is how much. And it is based on the duration, proximity, and frequency.
Q. But you don't know the dose.
A. That's a dose.
* * *
Q. Don't you have to know the amount of the chemical for the duration and the proximity and the frequency to calculate the dose for an individual?
A. Are you asking me general, or are you asking --
Q. I'll ask -- chlorothalonil specifically. For any of the pesticides involved in this case.
A. No.
Q. No? You don't need to know the amount?
A. Well, the amount was substantial based on what I have described.
300-303.4
The record is replete with this sort of exchange, which is along the lines of what courts have denominated as unscientific ipse dixit (or assertions which are made but not proven). Cf. Gen. Elec. Co. v. Joiner , 522 U.S. 136, 146, 118 S. Ct. 512, 519, 139 L.Ed.2d 508 (1997) ("[N]othing in ... the Federal Rules of Evidence requires a district court to admit opinion evidence that is connected to existing data only by the ipse dixit of the expert."). Ultimately, Dr. Brautbar resorted to faulting the appellant companies for the lack of data underlying his opinions concerning substantial-factor causation. See, e.g. , N.B. at 900 (reflecting Dr. Brautbar's response to an appellant's attorney that, an "[e]xposure model can be made if I'm provided with some data from all of you of air monitoring, which wasn't provided. So I'm going to throw this back to you."). There is, of course, no suggestion on this record that this sort of burden-shifting rationale reflects a generally accepted scientific methodology.5
The majority's holding appears to be that a trial judge must hew more closely to crediting or discrediting the competing expert testimony about what any particular study or studies say, rather than actually looking at the studies themselves in the Frye context. See, e.g. , Majority Opinion, at 460–61, 464–65. Respectfully, I believe this imposes an unreasonable constraint on the trial courts’ ability to perform the essential review for reliability. In this regard, I fail to see how judges can be expected to test competing opinions from experts while being constrained in their ability to review the opinions’ underpinnings. Accord Walsh v. BASF Corp. , 191 A.3d 838, 849-50 (Pa. Super. 2018) (Bender, P.J.E., dissenting). And, upon such consideration, where the judge discerns a lack of appropriate scientific methodology, I cannot agree that it is inappropriate for him to so hold.
I also agree with Judge Wettick and Appellants that both of Appellee's experts inappropriately extrapolated from "pesticides" as a product class -- including numerous pesticides that Mr. Walsh never used -- to Appellees’ specific products, with no analysis of whether the products were chemically, functionally, or toxicologically similar. Accord McClain , 401 F.3d at 1245-46 (explaining that ignoring differences in chemical structure "does not make for reliable opinions in toxic tort cases"). There is also abundant record evidence confirming that this form of extrapolation lacks general acceptance in the scientific community. See, e.g. , Deposition of David H. Garabrant, M.D., dated Jan. 7, 2016, at 36-37 (analogizing Dr. Zambelli-Weiner's opinion to the rendering of a homogenous opinion with respect to the toxic effects of such diverse substances as "a shot of bourbon, purified water, sugar-sweetened beverages like soda, beer," simply because all are beverages).6
With regard to Dr. Zambelli-Weiner specifically, I find Judge Wettick's assessment to be compelling that:
Dr. Zambelli-Weiner's opinion regarding pesticides as a class is not in accordance with generally accepted scientific methodology because it fails to account for variations in composition of the universe of chemicals, compounds, or the like that might be considered a "pesticide." I find that failure to account for such an important variable is not in accordance with generally accepted scientific methodology.
Walsh v. BASF Corp. , No. GD-10-018588, slip op. at 19 (footnote omitted); accord Joint Brief for Appellants Bayer CropScience LP, Bayer Corp., Bayer CropScience Holding Inc. & Dow Agrosciences LLC at 35 ("There was no evidence, including from Plaintiff's experts, that, for example, citing studies about completely different products to support a causation opinion is conventional."); see also id. at 43 (remarking that the class of pesticides encompasses such substances as cayenne pepper, chlordane, canola oil, baking soda, and wood preservatives). As Judge Wettick aptly observed, Dr. Zambelli-Weiner herself recognized that "[p]esticides represent a heterogenous [, or diverse,] group of formulated products that contain active ingredients and additives." Walsh v. BASF Corp. , No. GD-10-018588, slip op. at 19 n.17 (citing Deposition of April Zambelli-Weiner, Ph.D., dated September 23, 2014, at 104-107) (emphasis in original).
In other cases, and along with other Justices, I have recognized the difficulties facing plaintiffs in toxic tort cases involving exposure to multiple products and long latency periods. See, e.g. , Gregg v. V-J Auto Parts, Inc. , 596 Pa. 274, 291-92, 943 A.2d 216, 226 (2007). Again, I would permit a fair degree of latitude, for example in terms of estimating exposure and dose. See, e.g. , Rost , 637 Pa. at 676 n.13, 151 A.3d at 1063 n.13 (Saylor, C.J., dissenting). However, the proffer -- before a jury of laypersons --- of expert witnesses whose methodologies are replete with ungrounded extrapolations and other analytical gaps, large-scale abstractions, and patent circularity goes far beyond any reasonable conception of appropriate leeway. Accord Accutane , 191 A.3d at 589 (emphasizing that the court's function on review of novel scientific opinions "is to distinguish scientifically sound reasoning from that of the self-validating expert, who uses scientific terminology to present unsubstantiated personal beliefs").
For the above reasons, I would reverse the order of the Superior Court.
II. Response to the Concurring Opinion by Justice Wecht
According to Justice Wecht, the opinion that I authored in Betz suffers from a "reliance upon potentially misleading terminology" and "so muddied the waters that this Court should stabilize its characterization of the Frye standard[.]" Concurring Opinion, at 465. In this regard, he intimates that Betz "introduced into Pennsylvania law a ‘conventionality’ requirement, suggesting that expert testimony in a scientific discipline is admissible only when the expert has ‘applied accepted scientific methodology in a conventional fashion in reaching his or her conclusions.’ " Id. at 470 (emphasis in original; citation omitted). Justice Wecht further cites, inter alia , to Commonwealth v. Jacoby , 642 Pa. 623, 170 A.3d 1065 (2017), as a decision evidencing the same deficiency which he attributes to Betz . See Concurring Opinion, at 470–71 & n.10.
As an initial matter, Justice Wecht's opinion demonstrates a misunderstanding of the Betz decision, in that the "conventional fashion" language simply wasn't used to redefine Frye ’s general-acceptance standard. Rather, the phrase appears, in Betz , solely in a section entitled, "The Decision to Conduct a Frye Hearing." Consistent with this heading, the passage discusses only the concept of the novelty of scientific evidence, which serves as the threshold to the entitlement to a Frye hearing. See Betz , 615 Pa. at 544-46, 44 A.3d at 52-53 ("We conclude that a Frye hearing is warranted when a trial judge has articulable grounds to believe that an expert witness has not applied accepted scientific methodology in a conventional fashion in reaching his or her conclusions." (emphasis added)).
Notably, this is the same limited context in which conventionality was considered in the Jacoby decision referenced by Justice Wecht. See Jacoby , 642 Pa. at 667, 170 A.3d at 1091. Indeed, the novelty threshold was the only tier of a Frye analysis that the Jacoby Court was able to review, given that the trial court had denied the defendant's motion for a Frye hearing, and accordingly, no application of the Frye general-acceptance test whatsoever had occurred in the case. See id. at 640, 170 A.3d at 1075.7
Viewing the contested phraseology in its appropriate setting, I do not find it to be confusing, at all, to say that scientific methodology applied in an unconventional fashion fairly translates into novel scientific evidence (particularly since novelty and unconventionality are often used as synonyms). And the Court's unanimous determination on this subject, in Betz , didn't stray off course. Instead, the question of whether the concept of novelty extended to novel (or unconventional) applications of otherwise-accepted scientific methodology was squarely presented by the litigants as a main, contested issue in the case.8 Furthermore, contrary to Justice Wecht's characterization, the matter was decided on amply-developed reasoning.9
In any event, the digression about passages from Betz dedicated to novelty seems to me to be of little relevance to this case, since the claim that prevailed before Judge Wettick was that Dr. Brautbar's methodology was not only unconventional, but it was wholly unscientific.10 One of the pillars of the Betz opinion is that trial judges are authorized -- and obliged upon proper challenge -- to screen against expert witnesses who profess to apply accepted scientific methodology but instead, present analyses suffering from material analytical gaps. See Betz , 615 Pa. at 553, 44 A.3d at 57-58. The alternative to permitting trial courts to consider whether experts actually adhere to the methodology that they only facially espouse is to accept the sort of expert self-validation which is of great concern to most courts.11
One need look no further than the FBI's recent revelation that, for decades, the government engendered the presentation of faulty forensic-science evidence -- in the form of microscopic hair analysis -- potentially impacting tens of thousands of criminal cases across the nation. See FBI Press Release, FBI Testimony on Microscopic Hair Analysis Contained Errors in at Least 90 Percent of Cases in Ongoing Review , at 2 (Apr. 2, 2015). Of course, the misuse of science in courtrooms tends to impugn the integrity of the judicial system. See, e.g. , Commonwealth v. Chmiel , 643 Pa. 216, 225, 173 A.3d 617, 622 (2017) (referencing a Washington Post article charging that the FBI's review was "a watershed in one of the country's largest forensic scandals, highlighting the failure of the nation's courts for decades to keep bogus scientific information from juries" (emphasis added)). See generally Edward J. Imwinkelreid, The Best Insurance Against Miscarriages of Justice Caused By Junk Science: An Admissibility Test That Is Scientifically and Legally Sound , 81 ALB. L. REV. 851, 851 (2018) ("Inaccurate expert testimony is a ‘recurrent theme[ ]’ in wrongful conviction studies.").
Accordingly, courts that look beyond mere acceptance of an expert's own personal claim to adherence to an accepted scientific methodology quite appropriately seek to protect the integrity of the judicial process.
Notably, other jurisdictions adhering to Frye ’s general-acceptance litmus have approved judicial screening against the admission of faulty expert analyses in a fashion very similar to that required under Betz . See, e.g. , Goeb v. Tharaldson , 615 N.W.2d 800, 816 (Minn. 2000) (applying a Frye analysis to require a proponent of scientific evidence to show that the "methodology used [by the expert] is reliable and in the particular instance produced reliable results ," and affirming the exclusion of testimony from an expert whose analysis made "too great a leap" from the data gathered (emphasis added)). See generally Blackwell v. Wyeth , 408 Md. 575, 971 A.2d 235, 254 (2009) ("The ‘analytical gap’ concept also has been employed by some of our sister states in a Frye analysis." (citing, inter alia , the Minnesota Supreme Court's decision in Goeb )).
Maryland maintains a variant of the Frye test which distinguishes between generally accepted methodology and generally accepted analysis, while clarifying that both are required "to avoid the pitfalls of an ‘analytical gap.’ " Blackwell , 971 A.2d at 255. In my view, it is largely a semantic issue whether an expert who professes to have applied a generally accepted scientific methodology -- but who has in fact failed to do so -- hasn't applied that methodology as a factual matter, or has been deficient in his applied reasoning. Under either understanding, the expert's unscientific and misleading testimony presents precisely the same danger associated with its misuse in a courtroom.
In this regard, a constant and contested theme, in this line of cases, is that one party's expert will say that he or she followed generally-accepted scientific methodology, and the adversary's expert will say this is not so. There would be no reason for a Frye hearing if a neutral judicial official were not interposed to resolve such a material factual dispute.
Nor was Betz ’s review of a scientist's actual methodology a novelty in Pennsylvania. In Blum v. Merrell Dow Pharmaceuticals, Inc. , the challenged expert testified at a Frye hearing that his opinions "were based on generally accepted methods." Blum by Blum v. Merrell Dow Pharmaceuticals, Inc. , 705 A.2d 1314, 1321 (Pa. Super. 1997), aff'd , 564 Pa. 3, 764 A.2d 1 (2000). Nevertheless, the Superior Court concluded that such self-validating testimony was "not enough" to carry the proponent's burden at a Frye hearing. Id. Significantly, in affirming this conclusion, this Court reviewed the record and explained that the expert "engaged in a selective review of the data from several" studies; "detached the underlying data from the controls set up by the studies"; and "worked backwards through the science, from the statistical results back to the studies in the first place." Blum , 564 Pa. at 7 n.5, 764 A.2d at 4 n.5. As such, and as in Betz , the Court concluded that "[t]his procedure cannot be fairly described as generally accepted methodology for purposes of the Frye standard." Id .
As I have previously explained, I don't believe the present case presents an appropriate vehicle for engaging in a merits defense of either the Frye or Daubert criteria or any other existing or proposed standard, since there is no present advocacy on the subject. I observe, however, that some of the authorities that Justice Wecht discusses in his defense of Frye depart greatly from his central thesis. For example, the concurrence references an article by law fellow and Ph.D. candidate James R. Dillon to support the propositions that judges lack the expertise to address scientific evidence in the courtroom, and that Frye more appropriately delegates the question of the reliability of the actual methodology or reasoning employed to experts selected by the litigants. See Concurring Opinion at 473–74 (citing James R. Dillon, Expertise on Trial , 19 COLUM. SCI. & TECH. L. REV. 247, 260, 272 (2018) ).
Relative to the comment about judicial expertise, however, the article also espouses the view that jurors lack the necessary competence to assess the reliability of scientific evidence. See, e.g. , Dillon, Expertise on Trial , 19 COLUM. SCI. & TECH. L. REV. at 278 (opining that "[j]urors often fail to understand and apply scientific testimony correctly, even when the underlying science itself is relatively clear," and that jurors tend to rely on "cognitive shortcuts," such as a focus upon "perceived expertise"). Moreover, the theme runs throughout the Dillon article that judges must implement an effective gatekeeping function to keep faulty science out of courtrooms, at the risk of compromising the integrity of the judicial system. In this regard, the author departs roundly from Justice Wecht's position concerning the effectiveness of traditional adversarial tools of common-law adjudication, including cross-examination, the introduction of competing evidence, and argumentation by counsel. Compare Concurring Opinion, at 467, with Dillon, Expertise on Trial , 19 COLUM. SCI. & TECH. L. REV. at 280 ("The empirical literature also casts doubt on the effectiveness of the traditional tools of the adversarial model ... in mitigating jurors’ cognitive fallibilities.").
The author further submits that the Frye approach, devised in 1923, had failed to counteract a "sporting theory" associated with the use of partisan expert witnesses in courtrooms, which was appalling to the public and produced a crisis of confidence in the judicial system, at least until courts began to "apply Frye more stringently in the 1970s." Id. at 259. Ultimately, the author proposes the appointment of a "scientific adjunct with expertise in each relevant scientific domain," in every civil and criminal case, who would have the authority to engage in sua sponte gatekeeping; to conduct and implement independent research and analyses, respectively; and to overturn jury verdicts which the adjunct finds to be contrary to scientific fact. Id. at 297-300.
Plainly, this article does not comport with Justice Wecht's position that Pennsylvania should remain "a Frye stalwart" with no further consideration of any other alternative. Compare Concurring Opinion, at 470, with Dillon, Expertise on Trial , 19 COLUM. SCI. & TECH. L. REV. at 312 ("Maintaining the status quo is not a viable option.").
Personally, at this point in time, I wouldn't endorse the Dillon article any more than I would subscribe to Justice Wecht's sua sponte defense of Frye . Instead, I reiterate my belief that very serious and difficult questions remain that would be better addressed by this Court upon developed argumentation and with due consideration of the many concerns arising out of the ongoing experience with the misuse of faulty science in courtrooms.
I note that there are other proposals for improvement that may also merit serious consideration. See, e.g. , Imwinkelreid, The Best Insurance Against Miscarriages of Justice Caused By Junk Science: An Admissibility Test That Is Scientifically and Legally Sound , 81 ALB. L. REV. at 865-66.
Notably, as well, the Betz Court never made a definitive ruling as to whether trial courts could separately enforce Rule of Evidence 702's requirement that expert opinion must assist the trier of fact to understand the evidence or determine a fact in issue, or Rule 403 ’s screening requirement against unfair prejudice, confusion of the issues, or misleading of the jury. See Pa.R.E. 403, 702. From my point of view, close consideration also should be accorded to empowering trial courts to separately enforce these material requirements in the expert-testimony arena. But see Majority Opinion, at –––– n.7 ("To the extent that Pennsylvania trial courts conduct an ‘essential review for reliability,’ that review may consist only of establishing that the expert utilized generally accepted methodologies in reaching his or her scientific conclusions." (internal citation omitted)).
Justice Todd joins this dissenting opinion.