[ J
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- Donohue, J.] IN THE SUPREME COURT OF PENNSYLVANIA

WESTERN DISTRICT

RICHARD THOMAS WALSH , EXECUTOR OF THE ESTA TE OF THOMAS J. WALSH, DEC EASED

v.

BASF CORPORATION; BAYER CORPORATION D/B/A BAYER CROPSCIENCE, L.P., A ND BAYER CROPSCIENCE HOLDING, INC., AND/OR BAYER CROPSCI ENCE, L.P. AND BAYER CROPSCIENC E HOLDING, INC., IN THEIR OWN R IGHT; BIOSAFE SYSTEMS, L.L.C.; CHE MTURA CORPORATION; CLEARY CHEMICAL CORP.; DOW AGROSCIEN CES, L.L.C.; E.H. GRIFFITH, INC.; E.I . DU PONT DE NEMOURS AND CO., INC .; G.B. BIOSCIENCES CORPORAT ION; JOHN DEERE LANDSCAPING, I NC., SUCCESSOR TO LESCO, INC.; MONSANTO COMPANY; NU FARM AMERICAS, INC.; REGA L CHEMICAL CO.; SCOTTS

- SIERRA C ROP PROTECTION CO.; AND SYNGENTA CROP PROTECTION, INC.
APPEAL OF: DOW AGROS CIENCES, LLC, BAYER CROPSCIEN CE, LP, BAYER CORPORATION, A ND BAYER CROPSCIENCE HOLDING, INC

. : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : No. 14 WAP 2019 Appeal from the Order of the Superior Court entered 6/20/18 at No. 1661 WDA 2016 vacating the order of the Court of Common Pleas of Allegheny County entered 10/14/16 at No. GD 10

- 018588 and remanding

ARGUED: October 16, 2019

RICHARD THOMAS WALSH , EXECUTOR OF THE ESTA TE OF THOMAS J. WALSH, DEC EASED : : : : : No. 15 WAP 2019 Appeal from the Order of the Superior Court entered 6/20/18 at No. 1661 WDA 2016 vacating the order of the Court of[J

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BASF CORPORATION; BAYER CORPORATION D/B/A BA YER CROPSCIENCE, L.P., A ND BAYER CROPSCIENCE HOLDING, INC., AND/OR BAYER CROPSCI ENCE, L.P. AND BAYER CROPSCIENC E HOLDING, INC., IN THEIR OWN R IGHT; BIOSAFE SYSTEMS, L.L.C.; CHE MTURA CORPORATION; CLEARY CHEMICAL CORP.; DOW AGROSCIEN CES, L.L.C.; E.H. GRIFFITH, INC.; E.I. DU PONT DE NEMOURS AND CO., INC .; G.B. B IOSCIENCES CORPORATI ON; JOHN DEERE LANDSCAPING, I NC., SUCCESSOR TO LESCO, INC.; MONSANTO COMPANY; NU FARM AMERICAS, INC.; REGA L CHEMICAL CO.; SCOTTS

- SIERRA C ROP PROTECTION CO.; AND SYNGENTA CROP PROTECTION, INC

. APPEAL OF: DEERE & COMPANY : : : : : : : : : : : : : : : : : : : : : : : : : : : Common Pleas of Allegheny County entered 10/14/16 at No. GD 10

- 018588 and remanding

ARGUED: October 16, 2019

RICHARD THOMAS WALSH , EXECUTOR OF THE ESTATE OF THOMAS J. WALSH, DEC EASED

v.

BASF CORPORATION; BAYER CORPORATION D/B/A BA YER CROPSCIENCE, L.P., A ND BAYER CROPSCIENCE HOLDING, INC., AND/OR BAYER CROPSCI ENCE, L.P. AND BAYER CROPSCIENC E HOLDING, INC., IN THEIR OWN R IGHT; BIOSAFE SYSTEMS, L.L. C.; CHEMTURA : : : : : : : : : : : : : : : : No. 16 WAP 2019 Appeal from the Order of the Superior Court entered 6/20/18 at No. 1661 WDA 2016 vacating the order of the Court of Common Pleas of Allegheny County entered 10 /14/16 at No. GD 10

- 018588 and remanding

ARGUED: October 16, 2019[J

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CORPORATION; CLEARY CHEMICAL CORP.; DOW AGROSCIEN CES, L.L.C.; E.H. GRIFFITH, INC.; E.I. DU PONT DE NEMOURS AND CO., INC .; G.B. BIOSCIENCES CORPORAT ION; JOHN DEERE LANDSCAPING, I NC., SUCCESSOR TO LESCO, INC.; MONSANTO COMPANY; NU FARM AMERICAS, INC.; REGAL CHEMICAL CO.; SCOTTS

- SIERRA C ROP PROTECTION CO.; AND SYNGENTA CROP PROTECTION, INC

. APPEAL OF: SYNGENTA CROP PROTECTION, INC. : : : : : : : : : : : : : : :

RICHARD THOMAS WALSH , EXECUTOR OF THE ESTA TE OF THOMAS J. WALSH, DEC EASED

v.

BASF CORPORATION; BAYER CORPORATION D/B/A BA YER CROPSCIENCE, L.P., A ND BAYER CROPSCIENCE HOLDING, INC., AND/OR BAYER CROPSCI ENCE, L.P. AND BAYER CROPSCIENC E HOLDING, INC., IN THEIR OWN R IGHT; BIOSAFE SYSTEMS, L.L.C.; CHE MTURA CORPORATION; CLEARY CHEMICAL CORP.; DOW AGROSCIEN CES, L.L.C.; E.H. GRIFFITH, INC.; E.I. DU PONT DE NEMOURS AND CO., INC .; G.B. BIOSCIE NCES CORPORATION; JO HN DEERE LANDSCAPING, I NC., SUCCESSOR TO LESCO, INC.; MONSANTO COMPANY; NU FARM AMERICAS, INC.; REGA L CHEMICAL CO.; SCOTTS

- SIERRA C ROP PROTECTION CO.; AND SYNGENTA CROP PROTECTION, INC

. : : : : : : : : : : : : : : : : : : : : : : : : : : : : No. 17 WAP 2019 Appeal from the Order of the Superior Court entered 6/20/18 at No. 1661 WDA 2016 vacating the order of the Court of Common Pleas of Allegheny County entered 10/14/16 at No. GD 10

- 018588 and remanding

ARGUED: October 16, 2019[J

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APPEAL OF: MONSANTO COMPANY : :

RICHARD THOMAS WALSH , EXECUTOR OF THE ESTATE OF THOMAS J. WALSH, DEC EASED

v.

BASF CORPORATION; BAYER CORPORATION D/B/A BA YER CROPSCIENCE, L.P., A ND BAYER CROPSCIENCE HOLDING, INC., AND/OR BAYER CROPSCI ENCE, L.P. AND BAYER CROPSCIENC E HOLDING, INC., IN THEIR OWN R IGHT; BIOSAFE SYSTEMS, L.L. C.; CHEMTURA CORPORATION; CLEARY CHEMICAL CORP.; DOW AGROSCIEN CES, L.L.C.; E.H. GRIFFITH, INC.; E.I. DU PONT DE NEMOURS AND CO., INC .; G.B. BIOSCIENCES CORPORAT ION; JOHN DEERE LANDSCAPING, I NC., SUCCESSOR TO LESCO, INC.; MONSANTO COMPANY; NU FARM AMERICAS, INC.; REGAL CHEMICAL CO.; SCOTTS

- SIERRA C ROP PROTECTION CO.; AND SYNGENTA CROP PROTECTION, INC

. APPEAL OF: BASF CORPORATION : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : No. 18 WAP 2019 Appeal from the Order of the Superior Court entered 6/20/18 at No. 1661 WDA 2016 vacating the order of the Court of Common Pleas of Allegheny County entered 10/14/16 at No. GD 10

- 018588 and remanding

ARGUED: October 16, 2019

DISSENTING OPINION

CHIEF JUSTICE SAYLOR DECIDED: JULY 21, 2020

The majority deems it inconsequential whether or not this Court should denominate trial judges as gatekeepers relative to the admission of novel scientific[J

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evidence in Pennsylvania courtrooms. See Majority Opinion, slip op. at 20. Personally, however, I find this to be the clear purport of most of t his 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 r eliability 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 t he 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. , 191 A.3d 560, 589 (N.J. 2018) (explaining that “the gatekeeping function prev ents 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 i nterposed 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[J

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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 de gree 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, slip op. at 17

- 18, I respectfully disassociate myself from that view. Accord Grady v. Fri to

- Lay, Inc. , 576 Pa. at 570 , 839 A.2d at
10 52 (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 favo r 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 main stream 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 refinemen t 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 liter ature 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.[J

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Indeed, the record support for Judge Wettick’s conclusion includes the tes timony 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 , R EFERENCE M ANUAL ON S CIENTIFIC E VIDENCE 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,
howev er, 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

1 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 __.”

2 See, e.g. , McClain v. Metabolife Int’l, Inc. , 401 F.3d 1233, 1241

- 42 (1 1 th 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 (5 th Cir. 20 04) (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. , 1 02 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 (continued...)[J

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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 toxico logist 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. 1 3, 2016, at 4 9 (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
(...continued) 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 admiss ibility 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 (20 16) (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, howev er, 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.

3 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 (continued...)[J

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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 coun sel 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 muc h besides saying substantial?

A. Well, substantial is how much. And it is based on the duration, proximity, and frequency.

(...continued) which he invoked in a reliable manner. See id. at 101. Rather, Dr. Garabrant testified that Dr. Brautbar “cherry pick[ed].” Id. at 127. I n 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.[J

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- 10 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 dur ation 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 w hich are made but not proven). Cf. G en. Elec. Co. v. Joiner , 522 U.S. 136, 146, 118 S. Ct. 512, 519 (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 th e ipse dixit of the expert

. ” ).

4 Although he repeatedly denied it, much of the purport of Dr. Brautbar’s testimony was t hat, 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 Agroscienc es LLC at 28.[J

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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 ap pellant’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

o r studies say, rather than actually looking at the studies themselves in the Frye
context. See, e.g. , Majority Opinion, slip op. at 25

- 26, 32. 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, 8 49

- 50 (Pa.

5 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 a s the majority recognizes , a defense expert t estified, consistent with Judge Wettick’s opinion, that this theory is wholly un supported 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 f ind 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).[J

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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 Appe llants 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 resp ect 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

6 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, slip op. at 29. 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

- 3 01, 552, 798.

Dr. Zambelli

- Weiner also extrap olated 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, acc ord 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)

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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 th e 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 1 9 (footnote omitted); acc ord 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 1 9 n.17 (citing Deposition of Ap ril 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 l ong 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, 15 1 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 circ ularity[J

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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 reason ing 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 , slip op. at 5. 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 meth odology in a conventional fashion in reaching his or her conclusions.’” Id. at 14 (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, slip op. at 14 & 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 scien tific 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 h as not[J

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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 accordi ngly, 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 subjec t, in Betz , didn’t stray off course. Instead, the question of

7 The “conventional fashion” language taken from Betz was also used in this manner in each of the remaining d ecisions 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); Com monwealth v. Walker , 625 Pa. 450, 489, 92 A.3d 766, 790 (2014) ; Com monwealth 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. S ee Jacoby , 642 Pa. at 667, 170 A.3d at 1091. On the novelty issue, however, Betz only decided the issue that was before the Court

-- i.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).[J

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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

8 In th is regard, the issue was raised and developed

-- and discussed extensively

-- by the parties and their amici

. C ompare 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 (s ummariz ing the plaintiff

- appellees’ argument that there was “no justification for conducting a Frye hearing,” since their expert’s methodology was “utterly mainstream” ).

9 Betz relates that Pennsylvania courts tend to downplay access to oth er 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 cour ts'

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 par t 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 5 58, 839 A.2d at 1045; Topa, 471 Pa. at 231

– 33, 369 A.2d at 1281

– 82. It would be naïve, in this (continued...)[J

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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 cha llenge

-- 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.

(...continued) 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

.

10 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, t he 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 hearin g) 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 opinions

-- i.e. material analytical gaps and abst ractions

-- is and should be excluded from courtrooms. See infra

.[J

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The alternative to permitting trial court s 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, fo r 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 M icroscopic Hair Analysis Contained Errors in at Least 90 Percent of Cases in Ongoing Review , at 2

11 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 qu estion, even when de minim i s , is a substantial cause of the injury. Concurring Opinion, slip op. at 20. In Betz , however, there simply was no reason for the Court to infer anything about substantial

- factor causation from discussions by the challenged exp ert 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 spec ific opinion at issue was that de minimus exposure -- i.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, slip op. at 20

- 21. I have acknowledged nonet heless, 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.[J

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(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 scien tific 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 A LB

. L. R EV

. 851, 851 (2 018) (“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 requir e a proponent of scientific evidence to show that the “methodology used [by the expert] is reliable and in the particular inst

ance 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 , 971 A.2d 235, 254 (Md. 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 )). 12

12 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 p rofesses to have applied a (continued...)[J

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Nor was Betz

’s review of a scientist’s actual methodology a novelty in Pennsylvania. In Blum v. Merre ll 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 explaine d 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 f irst 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, h owever, that some of the authorities that Justice Wecht (...continued) 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 un scientific 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.[J

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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 propositio ns 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 Concurr ing Opinion at 19 (citing James R. Dillon, Expertise on Trial , 19 C OLUM

. S CI

. & T ECH

. L. R EV

. 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 C OLUM

. S CI

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. 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 sc ience 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, i ncluding cross

- examination, the introduction of competing evidence, and argumentation by counsel. Compare Concurring Opinion, slip op. at 8, with Dillon, Expertise on Trial , 19 C OLUM

. S CI

. & T ECH

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. 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 wi th the use of partisan expert witnesses in courtrooms, which was appalling to the public and produced a crisis of confidence in the[J

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judicial system, at least until courts began to “apply Frye more stringently in the 1970s.”
Id. at 259. Ultimately, the au thor 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 , th is 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, slip op. at 13, with Dillon, Expertise on Trial , 19 C OLUM

. S CI

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. 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

. 13 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. 14

13 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 A LB

. L. R EV

. at 86 5

- 66.

14 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 requirement s in the expert

- testimony arena. But see Majority Opinion, slip op. at 21 n.7 (“To the extent that Pennsylvania trial courts conduct an ‘essential (continued...)[J

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Justice Todd joins this dissenting opinion.

(...continued) review for reliability,’ that review may consist only of establishing that the expert utilized generally acc epted methodologies in reaching his or her scientific conclusions.” (internal citation omitted)).