Judicial Dodgers – Weight not Admissibility

Another vacuous response to a methodological challenge under Rule 702 is to label the challenge as “going to the weight, not the admissibility” of the challenged expert witness’s testimony. Of course, a challenge may be solely focused upon the expert witness’s credibility, such as when an expert witness testifies on many occasions only for one side in similar disputes, or for one whose political commitments render him unable to acknowledge the bona fides of any studies conducted by the adversarial parties.[1] If, however, the Rule 702 challenge stated an objection to the witness’s methodology, then the objection would count against both the opinion’s weight and its admissibility. The judicial “weight not admissibility” label conveys the denial of the challenge, but it hardly explains how and why the challenge failed under Rule 702. Applying such a label without addressing the elements of Rule 702, and how the challenged expert witness satisfied those elements, is often nothing less than a failure of judging.

The Flawed Application of a Generally Accepted Methodology

If a meretricious expert witness by pretense or ignorance invokes a standard methodology but does so in a flawed or distorted, or in an invalid way, then there will be a clear break in the chain of inferences from data to conclusion. The clear language of Rule 702 should render such an expert witness’s conclusion inadmissible. Some courts, however, retreat into a high level of generality about the method used rather than inspecting the method as applied. For example, a court might look at an expert witness’s opinion and correctly find that it relied upon epidemiology, and that epidemiology is a generally accepted discipline concerned with identifying causes. The specific detail of the challenge may have shown that the witness had relied upon a study that was thoroughly flawed,[2] or that the witness relied upon an epidemiologic study of a type that cannot support a causal inference.[3]

Rule 702 and the Supreme Court’s decision in Joiner make clear that the trial court must evaluate the expert witness’s application of methodology and whether it actually supports valid inferences leading to the witness’s claims and conclusions.[4] And yet, lower courts continue to characterize the gatekeeping process as “hands off” the application of methodology and conclusions:

“Where the court has determined that plaintiffs have met their burden of showing that the methodology is reliable, the expert’s application of the methodology and his or her conclusions are issues of credibility for the jury.”[5]

This rejection of the clear demands of a statute has infected even the intermediate appellate United States Court of Appeals. In a muddled application of Rule 702, the Third Circuit approved admitting expert witness testimony in a case, explaining “because [the objecting party / plaintiff] objected to the application rather than the legitimacy of [the expert’s] methodology, such objections were more appropriately addressed on cross-examination and no Daubert hearing was required”).[6] Such a ruling in the Third Circuit is especially jarring because it violates not only the clear language of Rule 702, but also established precedent within the Circuit that holds that “any step that renders the analysis unreliable . . . renders the expert’s testimony inadmissible. This is true whether the step completely changes a reliable methodology or merely misapplies that methodology.”[7]

The Eight Circuit seems to have set itself up stridently against the law by distinguishing between scientific methodologies and their applications, and holding that “when the application of a scientific methodology is challenged as unreliable under Daubert and the methodology itself is otherwise sufficiently reliable, outright exclusion of the evidence in question is warranted only if the methodology was so altered by a deficient application as to skew the methodology itself.”[8]

The Ninth Circuit similarly has followed this dubious distinction between methodology in the abstract and methodology as applied. In City of Pomona, the Circuit addressed the admissibility of an expert witness whose testing deviated from protocols. Relying upon pre-2000 Ninth Circuit case law, decided before the statutory language of Rule 702 was adopted, the court found that:

“expert evidence is inadmissible where the analysis is the result of a faulty methodology or theory as opposed to imperfect execution of laboratory techniques whose theoretical foundation is sufficiently accepted in the scientific community to pass muster under Daubert.”[9]

The Eleventh Circuit has similarly disregarded Rule 702 by adverting to an improvised distinction between validity of methodology and flawed application of methodology.[10]

Cherry Picking and Inadequate Bases

Most of the Circuits of the United States Court of Appeals have contributed to the mistaken belief that “[a]s a general rule, questions relating to the bases and sources of an expert’s opinion affect the weight to be assigned that opinion rather than its admissibility.”[11] Clearly, such questions can undermine the admissibility of an expert witness’s opinion under Rule 702, and courts need to say why they have found the challenged opinion to have had a “sufficient basis.” For example, in the notorious Milward case, the First Circuit, citing legally invalid pre-Daubert decisions, stated that “when the factual underpinning of an expert’s opinion is weak it is a matter affecting the weight and credibility of the testimony − a question to be resolved by the jury.”[12]

After Milward, the Eighth Circuit followed suit in a hormone replacement therapy case. An expert who ignored studies was excluded by the district court, but the Court of Appeals found an abuse of discretion, holding that the sufficiency of an expert’s basis is a question of weight and not admissibility.[13]

These rulings elevate form over substance by halting the gatekeeping inquiry at an irrelevant, high level of abstraction, and finding that the challenged expert witness was doing something “sciencey,” which is good enough for government work. The courts involved evaded their gatekeeping duties and ignored the undue selectivity in reliance materials and the inadequacy and insufficiency of the challenged expert witness’s factual predicate. The question is not whether expert witnesses relied upon “scientific studies,” but whether their causal conclusions and claims are well supported, under scientific standards, by the studies upon which they relied.

Like the covert shifting of the burden of proof, or the glib assessment that the loser can still cross-examine in front of the jury,[14] the rulings discussed represent another way that judges kick the can on Rule 702 motions. Despite the confusing verbiage, these judicial rulings are a serious deviation from the text of Rule 702, as well as the Advisory Committee Note to the 2000 Amendments, which embraced the standard articulated in In re Paoli, that

“any step that renders the analysis unreliable . . . renders the expert’s testimony inadmissible. This is true whether the step completely changes a reliable methodology or merely misapplies that methodology.”[15]

On a positive note, some courts have recognized that responding with the conclusory assessment of a challenge’s going to weight not admissibility is a delegation of the court’s gatekeeping duty to the jury.[16]

In 2018, Professor Daniel Capra, the Reporter to the Rules Committee addressed the “weight not admissibility dodge” at length in his memorandum to the Rules Committee:

“Rule 702 clearly states that these are questions of admissibility, but many courts treat them as questions of weight. The issue for the Committee is whether something/anything can be done about these wayward decisions.”[17]

The Reporter charitably noted that the problem could be in the infelicitous expression of some courts that short-circuit their analyses by saying “I see the problems, but they go to the weight of the evidence.”[18] Perhaps these courts meant to say that they had found that the proponent of the challenged expert witness testimony had shown admissibility by a preponderance, and that what non-disqualifying problems remained should be taken up on cross-examination.[19] The principle of charity, however, cannot exonerate federal judges from exercising the dodge repeatedly in the face of clear statutory language. Indeed, the Reporter reaffirmed the Rules Committee’s substantive judgment that questions of sufficient basis and reliable application of methodology are admissibility issues:[20]

“It is hard to see how expert testimony is reliable if the expert has not done sufficient investigation, or has cherry-picked the data, or has misapplied the methodology. The same ‘white lab coat’ problem − that the jury will not be able to figure out the expert’s missteps − would seem to apply equally to basis, methodology and application.”

Although the Reporter opined that some authors may have overstated judicial waywardness, he found the judicial disregard of the requirements of Rule 702(b) and (d) incontrovertible.[21]

Professor Capra restated his conclusions a year later, in 2019, when he characterized broad statements such as such as “challenges to the sufficiency of an expert’s basis raise questions of weight and not admissibility” as “misstatement[s] made by circuit courts in a disturbing number of cases… .”[22] Factual insufficiency and unreliable application of methodology are, of course, also credibility and ethical considerations, but they are the fact finders’ concern only after the proponent has shown admissibility by a preponderance of the evidence. Principled adjudication requires judges to say what they mean and mean what they say.


[1]  See also Cruz-Vazquez v. Mennonite Gen. Hosp. Inc., 613 F.3d 54 (1st Cir. 2010) (reversing exclusion of an expert witness who was biased in favor of plaintiffs in medical cases and who was generally affiliated with plaintiffs’ lawyers; such issues of personal bias are for the jury in assessing the weight of the expert witness’s testimony). Another example would be those expert witnesses whose commitment to Marxist ideology is such that they reject any evidence proffered by manufacturing industry as inherently corrupt, while embracing any evidence proffered by labor or the lawsuit industry without critical scrutiny.

[2]  In re Phenylpropanolamine (PPA) Prods. Liab. Litig., MDL No. 1407, 289 F. Supp. 2d 1230 (W.D. Wash. 2003) (Yale Hemorrhagic Stroke Project).

[3]  Cook v. Rockwell Internat’l Corp., 580 F. Supp. 2d 1071, 1098 (D. Colo. 2006) (“Defendants next claim that Dr. Clapp’s study and the conclusions he drew from it are unreliable because they failed to comply with four factors or criteria for drawing causal interferences from epidemiological studies: accounting for known confounders … .”), rev’d and remanded on other grounds, 618 F.3d 1127 (10th Cir. 2010), cert. denied, ___ U.S. ___, 133 S.Ct. 22 (2012). For another example of a trial court refusing to see through important qualitative differences between and among epidemiologic studies, see In re Welding Fume Prods. Liab. Litig., 2006 WL 4507859, *33 (N.D. Ohio 2006) (reducing all studies to one level, and treating all criticisms as though they rendered all studies invalid)

[4]  General Electric Co. v. Joiner, 522 U.S. 136 (1997).

[5]  Proctor & Gamble Co. v. Haugen, 2007 WL 709298, at *2 (D. Utah 2007); see also United States v. McCluskey, 954 F.Supp.2d 1227, 1247-48 (D.N.M. 2013) (“the trial judge decides the scientific validity of underlying principles and methodology” and “once that validity is demonstrated, other reliability issues go to the weight − not the admissibility − of the evidence”); Murphy-Sims v. Owners Ins. Co., No. 16-CV-0759-CMA-MLC, 2018 WL 8838811, at *7 (D. Colo. Feb. 27, 2018) (“Concerns surrounding the proper application of the methodology typically go to the weight and not admissibility[.]”).

[6]  Walker v. Gordon, 46 F. App’x 691, 696 (3rd Cir. 2002).

[7]  In re Paoli R.R. Yard PCB Litig., 35 F.3d 717, 745 (3d Cir. 1994).

[8]  United States v. Gipson, 383 F.3d 689, 696 (8th Cir. 2004)(relying upon pre-2000 authority for this proposition).

[9]  City of Pomona v. SQM N.Am. Corp. 750 F.3d 1036, 1047 (9th Cir. 2014).

[10]  Quiet Tech. DC-8, Inc. v. Hurel-Dubois UK Ltd., 326 F.3d 1333, 1343 (11th Cir. 2003).

[11]  Puga v. RCX Sols., Inc., 922 F.3d 285, 294 (5th Cir. 2019). See also United States v. Hodge, 933 F.3d 468, 478 (5th Cir. 2019)(“As a general rule, questions relating to the bases and sources of an expert’s opinion affect the weight to be assigned that opinion rather than its admissibility and should be left for the jury’s consideration.”); MCI Communications Service Inc. v. KC Trucking & Equip. LLC, 403 F. Supp. 3d 548, 556 (W.D. La. 2019); Coleman v. United States, No. SA-16-CA-00817-DAE, 2017 WL 9360840, at *4 (W.D. Tex. Aug. 16, 2017); Alvarez v. State Farm Lloyds, No. SA-18-CV-01191-XR, 2020 WL 734482, at *3 (W.D. Tex. Feb. 13, 2020)(“To the extent State Farm wishes to attack the ‘bases and sources’ of Dr. Hall’s opinion, such questions affect the weight to be assigned to that opinion rather than its admissibility and should also be left for the jury’s consideration.”)(internal quotation and citation omitted); Patenaude v. Dick’s Sporting Goods, Inc., No. 9:18-CV-3151-RMG, 2019 WL 5288077, at *2 (D.S.C. Oct. 18, 2019) (“More fundamentally, each of these arguments goes to the factual basis of the report, … and it is well settled that the factual basis for an expert opinion generally goes to weight, not admissibility.”); Wischermann Partners, Inc. v. Nashville Hosp. Capital LLC, No. 3:17-CV-00849, 2019 WL 3802121, at *3 (M.D. Tenn. Aug. 13, 2019) (“[A]rguments that Pinkowski’s opinions are unreliable because he failed to review other relevant information and ignored certain facts bear on the factual basis for Pinkowski’s opinions, and, therefore, go to the weight, rather than the admissibility, of Pinkowski’s testimony.”).

[12]  Milward v. Acuity Specialty Products Group, Inc., 639 F.3d 11, 22 (1st Cir. 2011) (internal citations omitted), cert. denied sub nom., U.S. Steel Corp. v. Milward, 132 S. Ct. 1002 (2012).

[13]  Kuhn v. Wyeth, Inc., 686 F.3d 618, 633 (8th Cir. 2012): Kuhn v. Wyeth, Inc., 686 F.3d 618, 633 (8th Cir. 2012), rev’g Beylin v. Wyeth, 738 F.Supp. 2d 887, 892 (E.D.Ark. 2010) (MDL court) (Wilson, J. & Montgomery, J.) (excluding proffered testimony of Dr. Jasenka Demirovic who appeared to have “selected study data that best supported her opinion, while downplaying contrary findings or conclusions.”); see United States v. Finch, 630 F.3d 1057 (8th Cir. 2011) (the sufficiency of the factual basis for an expert’s testimony goes to credibility rather than admissibility, and only where the testimony “is so fundamentally unsupported that it can offer no assistance to the jury must such testimony be excluded”); Katzenmeier v. Blackpowder Prods., Inc., 628 F.3d 948, 952 (8th Cir. 2010)(“As a general rule, the factual basis of an expert opinion goes to the credibility of the testimony, not the admissibility, and it is up to the opposing party to examine the factual basis for the opinion in cross-examination.”); Paul Beverage Co. v. American Bottling Co., No. 4:17CV2672 JCH, 2019 WL 1044057, at *2 (E.D. Mo. Mar. 5, 2019) (admitting challenged opinion testimony without addressing the expert witness’s basis or application of methodology, following Eighth Circuit’s incorrect statement in Nebraska Plastics, Inc. v. Holland Colors Americas, Inc., 408 F.3d 410, 416 (8th Cir. 2005) that “[a]s a general rule, the factual basis of an expert opinion goes to the credibility of the testimony, not the admissibility, and it is up to the opposing party to examine the factual basis for the opinion in cross-examination[,]”). See alsoThe Fallacy of Cherry Picking As Seen in American Courtrooms” (May 3, 2014).

[14]  SeeJudicial Dodgers – Reassigning the Burden of Proof on Rule 702” (May 13, 2020); “Judicial Dodgers – The Crossexamination Excuse for Denying Rule 702 Motions” (May 11, 2020).

[15]  Fed. R. Evid. 702, Advisory Note (quoting In re Paoli RR Yard PCB Litig., 35 F.3d 717, 745 (3d Cir. 1994)).

[16]  See Nease v. Ford Motor Co., 848 F.3d 219, 231 (4th Cir. 2017) (“For the district court to conclude that Ford’s reliability arguments simply ‘go to the weight the jury should afford Mr. Sero’s testimony’ is to delegate the court’s gatekeeping responsibility to the jury.”).

[17]  Daniel J. Capra, Reporter’s Memorandum re Forensic Evidence, Daubert and Rule 702, at 1-2 (Apr. 1, 2018)

[18]  Id. at 43.

[19]  Id. at 43, 49-50.

[20]  Id. at 49-50.

[21]  Id. at 52.

[22]  Daniel J. Capra, Reporter, Reporter’s Memorandum re Possible Amendments to Rule 702, Advisory Comm. on Evidence Rules, Minutes of Meeting at 23 (May 3, 2019).

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