California Court of Appeal, Gary Garner v. BNSF Railway Company, Docket No. D082229

Causation Experts

 

Expert Opinion Testimony

 

Medical Expert

 

Survival and Wrongful Death Action

 

General Causation – Specific Causation

 

Exposure Necessary to Cause Specific Harm to Humans

 

Motion in Limine

 

California Law

 

 

 

Plaintiff Gary Garner appeals from a judgment entered against him after the trial court granted BNSF Railway Company’s (BNSF) motions in limine to exclude his causation experts, which resulted in the dismissal of his wrongful death lawsuit before trial. Gary alleged that during the more than four decades his father Melvin Garner spent working for BNSF, Melvin was continuously exposed to toxic levels of diesel exhaust and its chemical constituents. According to Gary, this exposure was a cause of Melvin’s non-Hodgkin’s lymphoma, which Melvin developed after retiring from BNSF and which led to his death in 2014. Gary retained several experts to perform a cancer risk assessment and opine on whether diesel exhaust and its constituents are capable of causing cancer, including non-Hodgkin’s lymphoma, and whether Melvin’s workplace exposure to diesel exhaust in this case was in fact a cause of his cancer. At the outset of trial, however, the trial court granted BNSF’s motions in limine to exclude Gary’s three causation experts from trial, finding that the science the experts relied on was inadequate and there was too great an analytical gap between the data and their opinions. The trial court then entered judgment in favor of BNSF and dismissed the case. Because the court’s in limine rulings resulted in the equivalent of a nonsuit, we conduct an independent review of the record to determine whether BNSF’s motions were properly granted. We conclude that the trial court erred in excluding Gary’s experts and therefore reverse the orders and judgment with instructions to the trial court to enter new orders denying BNSF’s motions in limine.

 

 

In October 2017, Melvin’s son, Gary Garner, filed this survival and wrongful death action against BNSF, alleging violation of the Federal Employers’ Liability Act (45 U.S.C. §51, et seq.) (FELA).

 

 

After the court’s denial of BNSF’s summary judgment motion, the parties engaged in expert discovery in February and March 2021. The parties also began filing and opposing motions in limine in March 2021 in accord with the then-scheduled trial date.

 

 

“General causation” refers to whether a substance is capable of causing a particular injury or condition in the general population. “Specific causation” refers to whether the substance caused a particular individual’s injury or condition. (Knight v. Kirby Inland Marine Inc. (5th Cir. 2007) 482 F.3d 347, 351.) (Fn. 3).

 

 

(…) In short, “section 801 governs judicial review of the type of matter” relied on by the expert, while “section 802 governs judicial review of the reasons for the opinion.” (Sargon, supra, 55 Cal.4th at p. 771; see §§ 801, subd. (b), 802.) The Supreme Court has therefore explained that, under these sections, “the trial court acts as a gatekeeper to exclude expert opinion testimony that is (1) based on matter of a type on which an expert may not reasonably rely, (2) based on reasons unsupported by the material on which the expert relies, or (3) speculative.” (Sargon, at pp. 771–772; see §§801, subd. (b), 802.) The Court has warned, however, that trial courts must “be cautious in excluding expert testimony. The trial court’s gatekeeping role does not involve choosing between competing expert opinions.” (Sargon, supra, 55 Cal.4th at p. 772.) “The gatekeeper’s focus ‘must be solely on principles and methodology, not on the conclusions that they generate.’” (Ibid.) Nor should the court determine the persuasiveness of an expert’s opinion, weigh the opinion’s probative value, substitute its own opinion for the expert’s opinion, or resolve scientific controversies. (Ibid.) Rather, the goal “is simply to exclude ‘clearly invalid and unreliable’ expert opinion.” (Ibid.)

 

 

As Gary argues, there is no requirement that a causation expert rely on a specific study or other scientific publication expressing precisely the same conclusion at which the expert has arrived. (Kennedy v. Collagen Corp. (9th Cir. 1998) 161 F.3d 1226, 1229 (Kennedy) [“it is scientifically permissible to reach a conclusion on causation without [epidemiological or animal] studies” showing a causal link]; Wendell v. GlaxoSmithKline LLC (9th Cir. 2017) 858 F.3d 1227, 1237 (Wendell) [“Perhaps in some cases there will be a plethora of peer reviewed evidence that specifically shows causation. However, such literature is not required in each and every case.”]; Turner v. Iowa Fire Equipment Co. (8th Cir. 2000) 229 F.3d 1202, 1208–1209 [“‘we do not believe that a medical expert must always cite published studies on general causation in order to reliably conclude that a particular object caused a particular illness’”].)

 

 

This makes sense for several reasons. First, “publication...is not the sine qua non of admissibility; it does not necessarily correlate with reliability [citation], and in some instances well-grounded but innovative theories will not have been published. [Citation.] Some propositions, moreover, are too particular, too new, or of too limited interest to be published.” (Daubert v. Merrell Dow Pharms., Inc. (1993) 509 U.S. 579, 593 (Daubert); see also Primiano v. Cook (9th Cir. 2010) 598 F.3d 558, 565 [“Peer reviewed scientific literature may be unavailable because the issue may be too particular, new, or of insufficiently broad interest, to be in the literature.”].) As Dr. Salmon explained, this is such a case because few studies of the potential link between diesel exhaust and non-Hodgkin’s lymphoma have been conducted. “‘The first several victims of a new toxic tort should not be barred from having their day in court simply because the medical literature, which will eventually show the connection between the victims’ condition and the toxic substance, has not yet been completed.’” (Wendell, supra, 858 F.3d at p. 1237.) Second, although “epidemiology focuses on the question of general causation,” it “cannot prove causation; rather, causation is a judgment for epidemiologists and others interpreting the epidemiologic data.” (Green et al., Reference Guide on Epidemiology, in Reference Manual on Scientific Evidence (3d ed. 2011) 549, 552, 598.) Epidemiological studies merely identify associations, which do not equate to causation. (See id. at pp.551– 553.) It is up to the expert to “bridge the gap between association and causation” and make that informed judgment. (Kaye and Freedman, Reference Guide on Statistics, in Reference Manual on Scientific Evidence (3d ed. 2011) 211, 217–218 (Statistics); accord Amador v. 3M Co. (In re Bair Hugger Forced Air Warming Devices Prods.Liab.Litig.) (8th Cir. 2021) 9F.4th 768, 778–780 [concluding it was not unreliable for an expert to rely on a study to draw an inference of causation even though the study found that the association did not establish causation, “so long as the expert does the work ‘to bridge the gap between association and causation’”].) “Whether an inference of causation based on an association is appropriate is a matter of informed judgment, not scientific methodology....” (Rest.3d Torts, § 28 (2010) (Restatement), com. (c), subd. (3), p. 406; see also id. at subd. (1), p. 403 [“An evaluation of data and scientific evidence to determine whether an inference of causation is appropriate requires judgment and interpretation.”]; Milward v. Acuity Specialty Prods. Group, Inc. (1st Cir. 2011) 639 F.3d 11, 18–19 (Milward) [same]; Statistics, supra, at p. 222 [“In the end, deciding whether associations are causal typically is not a matter of statistics alone, but also rests on scientific judgment.”].) And “scientific inference typically requires consideration of numerous findings, which, when considered alone, may not individually prove the contention.... In applying the scientific method, scientists do not review each scientific study individually for whether by itself it reliably supports the causal claim being advocated or opposed. Rather, as the Institute of Medicine and National Research Council noted, ‘summing, or synthesizing, data addressing different linkages [between kinds of data] forms a more complete causal evidence model and can provide the biological plausibility needed to establish the association’ being advocated or opposed.” (Berger, The Admissibility of Expert Testimony, in Reference Manual on Scientific Evidence (3d ed. 2011) 11, 19–20; see also Milward, at pp. 17–19 [discussing use of scientific judgment applying “weight of the evidence” approach for determining general causation].) It was therefore appropriate for Gary’s experts to use their experience and judgment to interpret the available epidemiological and other data they reviewed in reaching their causation opinions.

 

 

Dr. Salmon gave a reasonable scientific explanation for his causation opinions, including his reliance on the overall cancer risk, and he cited objective, verifiable evidence supporting his opinions. BNSF submitted no evidence that his reasoning or methodology was scientifically invalid. The trial court also found no fault with his methodology. The mere fact that a cause-effect relationship between exposure to diesel exhaust and non-Hodgkin’s lymphoma “in particular” has not been conclusively established in the scientific literature does not render Dr. Salmon’s opinions inadmissible. (Kennedy, supra, 161 F.3d at p.1230; see also Milward, supra, 639 F.3d at pp. 16, 19–20 [causation expert properly relied on scientific evidence that benzene can cause acute myeloid leukemia (AML) “as a class” as support for his opinion that workplace exposure to benzene caused plaintiff’s specific rare type of AML].)

 

 

On this record, leaving adequate space for the exercise of reasonable scientific judgment based on the available data, we conclude that the analytical gap was not “too great” for Dr. Salmon to bridge using his own scientific training and expertise. (Sargon, supra, 55 Cal.4th at p. 771.) The trial court strayed beyond its gatekeeping role by weighing the probative value of Dr. Salmon’s opinion, and the studies on which he relied, rather than merely excluding a clearly invalid and unreliable expert opinion. (See id. at p. 772; Cooper v. Takeda Pharmaceuticals America, Inc. (2015) 239 Cal.App.4th 555, 592 (Cooper).)

 

 

“While precise information concerning the exposure necessary to cause specific harm to humans and exact details pertaining to the plaintiff’s exposure are beneficial, such evidence is not always available, or necessary, to demonstrate that a substance is toxic to humans given substantial exposure and need not invariably provide the basis for an expert’s opinion on causation.” (Westberry v. Gislaved Gummi AB (4th Cir. 1999) 178 F.3d 257, 264; accord Sarkees v. E.I. Dupont De Nemours & Co. (2d Cir. 2021) 15 F.4th Cir. 584, 593; Clausen v. M/V New Carissa (9th Cir. 2003) 339 F.3d 1049, 1059–1060; Hardyman v. Norfolk & W.Ry.Co.(6th Cir. 2001) 243 F.3d 255, 265–266.)

 

 

 

 

Secondary sources: Green et al., Reference Guide on Epidemiology, in Reference Manual on Scientific Evidence (3d ed. 2011) 549, 552, 598; Kaye and Freedman, Reference Guide on Statistics, in Reference Manual on Scientific Evidence (3d ed. 2011) 211, 217–218; Berger, The Admissibility of Expert Testimony, in Reference Manual on Scientific Evidence (3d ed. 2011) 11, 19–20; Rest. 3d Torts, § 28 (2010); Proposed Guidelines for Carcinogen Risk Assessment, 61 Fed. Reg. 17960, 17993 (Apr. 23, 1996); Reference Manual on Scientific Evidence from the Federal Judicial Center.

 

 

 

 

(California Court of Appeal, Jan. 4, 2024, Gary Garner v. BNSF Railway Company, Docket No. D082229, Certified for Publication)