California’s Liberal Admissibility Standards Concerning Expert Exposure and Medical Causation Opinions

by Gregory A. Coolidge, Esq.

 

1.         Introduction

As discussed in the paper for this Conference authored by Richard O. Faulk and Diana L. Panian, “A Decade of Daubert: The Continuing Trend Toward Stricter Scrutiny of Expert Testimony in State Courts,” many states have indeed adopted versions of the standards for the admissibility of expert opinions set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) 509 U.S. 579. In their paper, Mr. Faulk and Ms. Panian correctly cite several recent cases in Texas and elsewhere in which courts have applied Daubert principles to exposure and medical causation experts. In such cases, courts required the exposure and medical causation opinions to be “generally accepted” within the scientific and medical community, required exposure experts to quantify the dose of the plaintiff’s exposure to the toxin(s) at issue, and required medical causation experts to rely on epidemiological studies which set forth the dose at which the risk of developing the disease at issue is increased. In such cases, trial courts were also permitted to evaluate the scientific and medical literature upon which the exposure and medical causation experts relied to determine whether such literature was “reliable” and actually supported the experts’ exposure and medical causation opinions.

After reviewing the cases cited by Mr. Faulk and Ms. Panian, I was struck by how fortunate I am to be a plaintiff’s attorney litigating toxic injury cases in California, because California employs some of the most liberal standards for the admissibility of expert exposure and medical causation opinions in the country. Indeed, as will be discussed herein, California courts, including the California Supreme Court, have rejected Daubert and have held that medical causation opinions are never subject to the “general acceptance” test set forth in Daubert or the Kelly-Frye Rule. Moreover, there is not a single California decision which requires an exposure or medical causation expert to quantify the plaintiff’s dose to the particular toxin(s) at issue in order to render admissible opinions, and courts which have addressed the issue have held that no such quantification is required.

There is also no requirement under California law that an expert’s opinion that a particular toxin is capable of causing a particular disease must be based on epidemiological studies. Finally, under California law, when performing its admissibility determination, a trial court is not permitted to evaluate the scientific and medical literature upon which the exposure and medical causation experts have relied to determine whether such literature is “reliable” and actually supports the experts’ opinions. Such is the admissibility determination employed by federal and state courts applying Daubert. In California, a trial court’s admissibility determination is limited to the general finding that the expert has relied on the type of subject matter which may reasonably be relied on by experts rendering such opinions, and such finding may not include a determination whether the medical literature on which an expert has relied is “reliable” and actually supports the experts’ opinions.

 

2.         The Kelly-Frye Rule Does Not Apply to Expert Medical Opinions

In their paper, Mr. Faulk and Ms. Panian state that “the California Supreme Court’s perspective on the [“Kelly-Frye” Rule] is actually much stricter than a simple evaluation of ‘general acceptance.’ Similar to Daubert, the court recently recognized that trial courts must perform a gate keeping function that only allows "evidence that is sufficiently reliable and trustworthy to reach jurors.” However, neither the California Supreme Court, nor any other California court, have held that the Kelly-Frye Rule applies to expert medical causation opinions, or that such opinions must be “generally accepted” within the medical and scientific community. To the contrary, all California courts which have addressed the issue have held that the Kelly-Frye Rule and “general acceptance test” never apply to the admissibility of medical causation opinions, even where the expert’s medical causation opinion derived from his review of medical studies is “novel.”

To understand the Kelly-Frye Rule, one should begin by considering the case which formed its basis: Frye v. United States (D.C. Cir. 1923) 293 F. 1013, 1014. The issue in the Frye case was whether expert testimony based on polygraph (lie detector) tests could be admitted notwithstanding the novelty and unreliability of such tests. The issue in the Kelly case was whether expert testimony based on speaker identification by spectrographic analysis tests (voice print tests) could be admitted notwithstanding the novelty of such tests. The courts in both cases held that expert testimony based on the novel scientific techniques was not admissible, because the techniques themselves were not generally recognized as valid by the scientific community.

The “Kelly-Frye” Rule is an exclusionary rule of evidence which allows courts to exclude expert testimony that is based on controversial scientific techniques. This is shown by the following passage in Kelly:

The test for determining the underlying reliability of a new scientific technique was described in the germinal case of Frye v. United States (D.C. Cir. 1923) 293 F. 1013, 1014, involving the admissibility of polygraph tests: “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.” (Emphasis added)

Kelly, supra, 17 Cal.3d at 30.

In People v. Stoll (1989) 49 Cal.3d 1136, the Supreme Court succinctly held: “Kelly/Frye only applies to that limited class of expert testimony which is based, in whole or part, on a technique, process, or theory which is new to science and, even more so, the law.” Id., 49 Cal.3d at 1156 (emphasis added). The continued vitality of the rule was affirmed by the Supreme Court in Daubert v. Merrell Dow Pharmaceuticals (1993) 509 U.S. 579.

The Leahy court noted since its decision in Kelly, the Court had numerous occasions to review and apply the doctrine in cases involving novel scientific techniques, and had done so without apparent difficulty or critical comment. Id. at 604, citing, People v. Diaz (1992) [3 Cal.4th 495], 525-528 [tissue sample analysis]; People v. Pride (1992) 3 Cal.4th 195, 238-239 [hair comparison analysis]; People v. Stoll (1989) 49 Cal.3d 1136, 1152-1161 [standardized personality tests]; People v. Bledsoe (1984) 36 Cal.3d 236; 245-251 [rape trauma syndrome]; People v. Shirley (1982) 31 Cal.3d 18, 51-54 [hypnotically induced testimony].

In each of the instances in which the Court applied the rule to exclude expert testimony, it did so not because of the opinion rendered by the expert, but because the scientific technique which formed the basis for the expert’s testimony had not been generally accepted by the scientific community. This is the proper application and scope of the rule. The Kelly rule has never been conceived as a rule allowing the exclusion of expert opinions which are not based on novel and unreliable scientific techniques.

The rationale underlying the rule is that the "misleading aura of certainty which often envelops a new scientific process," Huntingdon v. Crowley (1966) 64 Cal.2d 647, 656, "may in some instances assume a posture of mystic infallibility in the eyes of a jury." Kelly, 17 Cal.3d at 32, citing U.S. v. Addison (D.C. Cir. 1974) 498 F.2d 741, 744. This rationale only applies where an expert offers testimony based on novel scientific techniques. Two California cases decided in 1999 reaffirm the rule that expert testimony is not subject to exclusion under Kelly unless it is based on a novel and unproven black-box technology: Wilson v. Phillips (1999) 73 Cal.App.4th 250, 86 Cal.Rptr.2d 204, and People v. Ward (1999) 71 Cal.App.4th 368, 83 Cal.Rptr.2d 828.

In People v. Ward, the court explained the distinction between expert medical opinion and the admissibility of scientific tests as follows:

California distinguishes between expert medical opinion and scientific evidence; the former is not subject to the special admissibility rule of Kelly-Frye . . . . Kelly-Frye applies to cases involving novel devices or processes, not to expert medical testimony . . . .” Id., 71 Cal.App.4th at 373.

Quoting People v. McDonald (1984) 37 Cal.3d 351, 372-373, 690 P.2d 709, 208 Cal.Rptr. 236, 46 A.L.R.4th 1011, the Court in People v. Ward also explained why courts view expert medical testimony differently from evidence derived from scientific tests:

There is good reason why courts draw a distinction between expert medical testimony and evidence derived from a new scientific device or procedure. "When a witness gives his personal opinion on the stand—even if he qualifies as an expert—the jurors may temper their acceptance of his testimony with a healthy skepticism born of their knowledge that all human beings are fallible. But the opposite may be true when the evidence is produced by a machine: like many laypersons, jurors tend to ascribe an inordinately high degree of certainty to proof derived from an apparently 'scientific' mechanism, instrument, or procedure. Yet the aura of infallibility that often surrounds such evidence may well conceal the fact that it remains experimental and tentative."

In People v. Bui (2001) 86 Cal.App.4th 1187, the Court of Appeal affirmed the admission of a toxicologist’s opinion that methamphetamine blood levels correlate with impaired driving skill. The defendant contended the trial court erred in admitting the testimony, arguing it was based on a new scientific technique and was not generally accepted in the scientific community. However, the Court of Appeal rejected this argument, because the toxicologist’s opinion was based on epidemiological studies, case reports, and other medical literature. The Court noted that “epidemiological studies and reviews of existing literature are common, valid, and accepted tools of scientific research, which have been in use within the scientific community for the past 200 years.” Id. at 1196. The mere fact that the defendant’s expert disagreed with the toxicologist’s conclusions “does not make [his] methodology a new scientific technique.” Id.

The Court of Appeal for the Second Appellate District, in Roberti v. Andy’s Termite & Pest Control, Inc. (2003) 113 Cal.App.4th 893, examined the Kelly-Frye Rule, and held that a trial court may not exclude the medical causation opinions of a plaintiff’s experts because such opinions are not “generally accepted” in the medical and scientific community. In Roberti, a pesticide manufacturer filed an in limine motion to preclude the plaintiff’s medical experts from opining that plaintiff's autism was caused by exposure to the pesticide Dursban. In support of his theory that Dursban caused his autism, the plaintiff presented expert testimony of several toxicologists and medical doctors in which each stated the opinion to a reasonable degree of medical or scientific certainty that plaintiff's injuries and damages were caused by his household exposure to the Dursban used by defendant. The experts based their opinions on plaintiff's medical records, as well as on numerous peer-reviewed and non-peer-reviewed medical articles. The defendant contended that the expert opinions offered by plaintiff asserted only the possibility of causation, and were unsupported by peer-reviewed scientific and medical literature. Defendant later filed an amended motion in limine, contending that plaintiff's expert testimony was based on novel methodologies of scientific proof unsupported by peer-reviewed scientific literature, i.e., did not meet the “general consensus” admissibility test set forth in People v. Kelly (1976) 17 Cal.3d 24.

After reviewing the moving and opposing papers, the experts' depositions, declarations, and matter upon which the experts relied, the trial court held a hearing on the motion in limine. Thereafter the court granted the motion, ruling that "[t]he plaintiff's experts' analysis and causation opinions are not derived from any accepted scientific methodology, are not scientifically valid, and do not possess the evidentiary reliability required by Kelly. . . . The court must assure itself that opinions are based on relevant scientific methods, processes, and data and not upon an expert's mere speculation.” The court further noted that "[t]he consensus in the medical community is that there is no known cause of autism" and further that “[t]here is no consensus among the scientific community that pesticides cause autism." The trial court granted the defendant’s motion in limine.

After entry of a judgment of dismissal, plaintiff appealed, contending that Kelly’s general acceptance test did not apply to expert medical opinion testimony and the trial court had no authority to exclude the testimony of Plaintiffs’ medical experts based upon some threshold test of the admissibility akin to the Daubert standard used by federal courts. The Court of Appeal agreed that Kelly’s general acceptance test did not apply to expert medical causation opinion testimony and that the trial court lacked authority to apply a threshold admissibility test to the experts’ testimony like the Daubert standard used by the federal courts.

The Court of Appeal reasoned that Kelly’s general consensus test did not apply to plaintiff’s expert causation opinions:

Plaintiff's experts based their opinion testimony upon research papers and studies (primarily those conducted on animals) in peer-reviewed journals regarding Dursban and its effects, and to some extent upon physical examination of plaintiff using techniques that are generally accepted in the relevant medical community. They did not rely upon any new scientific technique, device, or procedure that has not gained general acceptance in the relevant scientific or medical community. Rather, it was the theory of causation, that Dursban caused plaintiff's autism, that has not gained general acceptance in the relevant medical community. The Kelly test is not applicable even though the proffered evidence presents a new theory of medical causation.

. . .

Wilson, supra, and Bui, supra, specifically hold that medical theories of causation are not subject to the Kelly Rule when they are based entirely upon generally accepted diagnostic methods and tests, including statistical studies that are not definitive. Bui, at page 1196, 86 Cal.App.4th 1187, reiterates the established principle that disagreement by an opposing party's expert with the conclusions a medical expert witness draws from accepted methods of scientific research "does not make [the challenged expert's] methodology a new scientific technique." Bui and other cases point out that opposing parties are free to present contrary expert testimony to refute a medical opinion because juries do not view the subjective thought processes of an expert as having the "aura of infallibility" they tend to attribute to scientific devices, techniques, or procedures. (Bui, supra, at pp. 1195-1196, 86 Cal.App.4th 1187.)

Defendant's objections are actually to the conclusions plaintiff's experts reached based on the studies available, not with the methodology used in the studies, upon which the experts relied in reaching their conclusions. Defendant's argument in this regard, and the trial court's ruling, instead pertains to the weight of the underlying bases for the expert opinion, not its admissibility. . . .

It is therefore clear under California law that an expert’s review and evaluation of medical studies for the purpose of rendering medical causation opinions is not a “new technique” which is subject to the Kelly/Frye Rule, even if the medical causation opinion derived from such review and evaluation is novel. Moreover, an expert’s medical causation opinion itself is never subject to the Kelly/Frye Rule, and therefore such opinions cannot be excluded simply because the expert’s opinions are not “generally accepted” in the medical and scientific community.

 

3.         An Expert Need Not Quantify the Dose of a Plaintiff's Exposure

There are no published California decisions in which a court has held that a plaintiff is required to provide expert testimony quantifying the dose of his exposure to a particular toxin in order to prove medical causation in a toxic injury action. To the contrary, California courts addressing the issue have held that a plaintiff, in order to establish exposure in a toxic injury action, need only introduce direct and/or circumstantial evidence which provides a reasonable inference that a plaintiff was exposed to a particular defendant’s product. Such evidence does not require a quantification of a plaintiff’s dose from a defendant’s products, whether through an inspection of the workplace, air monitoring, or otherwise, but can be limited to testimony and other direct and circumstantial evidence concerning the prevalence of the product at the work site and plaintiff’s proximity to dusts and fumes during the use of such products.

For instance, in Lineaweaver v. Plant Insulation Co. (1995) 31 Cal.App.4th 1409, 1420, a plaintiff suffering from asbestos-induced lung disease introduced circumstantial evidence of exposure, including the prevalence of defendant’s asbestos insulation product at the worksite and plaintiff’s testimony concerning plaintiff’s proximity to dusts when similar asbestos insulation products were removed. Plaintiff also introduced the testimony of an exposure expert, who based on the foregoing evidence (none of which included site inspections or air monitoring results), opined that plaintiff was exposed to asbestos fibers from defendant’s asbestos product. Plaintiff also introduced testimony from a medical causation expert who had estimated the dose of plaintiff’s exposure in “asbestos fiber years.” Based on the circumstantial evidence introduced by plaintiff, as well as the dose estimate of plaintiff’s expert, plaintiff’s medical causation expert opined that plaintiff’s exposure to defendant’s asbestos product was a substantial factor in causing his illness. The jury thereafter found that plaintiff’s exposure to defendant’s asbestos insulation was a substantial factor in causing his lung disease and awarded a verdict in plaintiff’s favor. Defendant appealed, arguing that plaintiff’s exposure and medical causation evidence was insufficient to support the exposure and medical causation opinions of plaintiff’s experts, particularly the “asbestos fiber years” dose estimate of plaintiff’s causation expert, which defendant contended was speculative and lacking in foundation. Id. at 1413-1414.

In reviewing plaintiff’s exposure and causation evidence, the Court of Appeal stated “[w]e look no further than established California law and long-standing tort principles to resolve the single issue put to us: was there evidence of sufficient substantiality to support a jury finding that asbestos supplied by respondent Plant was a cause of appellants' injuries?” The court thereafter held that plaintiff’s circumstantial exposure evidence was alone sufficient to support the jury’s verdict, because a plaintiff, in order to establish exposure to a defendant’s product in a toxic injury action, need only introduce direct and/or circumstantial evidence, such as the prevalence of the product at the work site and the plaintiff’s proximity to dusts from such products, which provides a reasonable inference that a plaintiff was exposed to a particular defendant’s product:

While there was no direct evidence that Lineaweaver was exposed to Plant-supplied Pabco, the circumstantial evidence was sufficient to support a reasonable inference of exposure. Unlike Dumin v. Owens-Corning Fiberglas Corporation, supra, 28 Cal.App.4th 650, in which we found insufficient evidence of exposure to a particular asbestos product, plaintiff has established that defendant's product was definitely at his work site and that it was sufficiently prevalent to warrant an inference that plaintiff was exposed to it . . . . Id. at 1420.

Concerning the issue of medical causation, the defendant in Lineaweaver thereafter argued that the medical causation opinions of plaintiff’s expert should have been excluded, because the expert’s opinion that plaintiff’s exposure to defendant’s asbestos products was a substantial factor in causing his illness was based on the expert’s speculative “asbestos fiber years” dose estimate of plaintiff’s exposure. The Lineaweaver court held that even if the dose estimate of plaintiff’s causation expert was completely disregarded, there was sufficient evidence, in the form of plaintiff’s testimony regarding his exposures and circumstantial evidence concerning the prevalence of defendant’s products at the worksite, for plaintiff’s medical causation expert to render the admissible opinion that plaintiff’s exposure to defendant’s asbestos products was a substantial factor in causing his illness:

As for biological causation, a physician expert in occupational medicine concluded that Lineaweaver's exposure to Pabco products was "a very substantial factor" in causing Lineaweaver's asbestosis. The physician, Dr. Richard Cohen, even opined that it is more likely than not that Lineaweaver would have developed asbestos-related disease from the exposure to Pabco products alone. [Defendant] disputes the validity of these opinions as based on unsupported quantification in "fiber-years" of Lineaweaver's exposure to Pabco. But the opinions of plaintiffs' experts and an inference of Pabco exposure as a substantial factor in contributing to Lineaweaver's asbestosis may be drawn from evidence independent of Dr. Cohen's quantification methodology.

As discussed above, Lineaweaver presented evidence of exposure to Plant-supplied Pabco on a regular basis over more than 30 years of working with and near asbestos insulation products. Lineaweaver was exposed to pipe covering and block insulation which is friable and "very powdery," and created visible dust reminiscent of a "snow storm." While there are other possible sources of Lineaweaver's asbestosis given his exposure to many different asbestos products, it is significant that Pabco products were prominent and prevalent at his work site. Viewing this evidence in Lineaweaver's favor, it was sufficient to support a jury's inference that exposure to Pabco products was a substantial factor in causing Lineaweaver's asbestosis. Id. at 1420-1421.

Similarly, in Sparks v. Owens-Illinois (1995) 32 Cal.App.4th 461, a plaintiff suffering from mesothelioma caused by his decades-long exposure to asbestos dusts from the asbestos insulation products of multiple defendants brought a products liability action against the numerous manufacturers of these products. The jury awarded a verdict in plaintiff’s favor, and in so doing found Owens-Illinois 100% at fault for causing plaintiff’s illness, even though plaintiff was exposed to asbestos dusts from the asbestos products of numerous settling defendants. Owens-Illinois appealed the verdict, and argued, in part, that plaintiff’s exposure and medical causation evidence failed to establish that Owens-Illinois’ “Kaylo” product was the sole cause of plaintiff’s mesothelioma. Plaintiff’s exposure and medical causation evidence included the opinions of several experts, none of whom calculated plaintiff’s asbestos dose, but rather opined, based on plaintiff’s testimony, that plaintiff’s exposure to asbestos dusts from Kaylo was “intense,” “substantial,” and sufficient in itself to cause Plaintiff’s illness. The Court of Appeal held that the opinions of plaintiff’s experts were sufficient to support the jury’s finding that plaintiff’s exposure to Kaylo was the sole cause of plaintiff’s mesothelioma.

The testimony of plaintiffs' medical experts was clearly sufficient to support a jury finding that Owens-Illinois's product, Kaylo, was more likely than not the source of asbestos fibers that caused Mr. Sparks's mesothelioma. Each of the experts testified that Sparks's exposure to asbestos-containing products during his time aboard the Bremerton was the first, and most intense period of exposure in his lifetime. Each of the medical experts also testified that Sparks's asbestos exposure on the Bremerton was almost certainly sufficient to have caused his mesothelioma. At least one of these experts further stated that Sparks's exposure to Kaylo during the decommissioning was, by itself, sufficient to have caused his disease. Sparks v. Owens-Illinois (1995) 32 Cal.App.4th 461, 476-477.

In so ruling, the Sparks court cited Lineaweaver’s exposure standard and noted that although the frequency and proximity of exposure are indeed relevant factors when determining exposure, such factors are not necessary to prove exposure in every case.

In a case decided while appellant's petition for rehearing was pending, Division One of this court discussed the burdens of proof on the issues of causation for asbestos-related personal injuries. (Lineaweaver v. Plant Insulation Co. (1995) 31 Cal.App.4th 1409, 1416 [37 Cal.Rptr.2d 902].) Writing for the majority, Justice Strankman held that the plaintiff has the burden of proving that "there [is] a reasonable medical probability based upon competent expert testimony that the defendant's conduct contributed to the plaintiff's injury." The court further observed that many factors are relevant in assessing the medical probability that an asbestos exposure was a "substantial factor" in causing the plaintiff's disease: "Frequency of exposure, regularity of exposure, and proximity of the asbestos product to plaintiff are certainly relevant, although these considerations should not be determinative in every case.” Sparks v. Owens-Illinois (1995) 32 Cal.App.4th 461, fn 11.

Moreover, in Rutherford v. Owens-Illinois (1997) 16 Cal.4th 953, a life-long smoker claimed that his cancer was caused by his exposure to asbestos from the numerous asbestos-containing insulation products of approximately 20 defendants. The jury found for Rutherford, apportioning 1.2% of fault to Owens-Illinois, 2.5% to Rutherford, and 96.3% to asbestos companies with whom Rutherford had settled before trial. Owens-Illinois appealed arguing that plaintiff had failed to prove that he was exposed to its asbestos product Kaylo and had also failed to prove that any of its asbestos caused the plaintiff’s lung cancer.

The Supreme Court held that to prevail in a toxic injury action involving multiple defendants and numerous toxic products, a plaintiff need not prove that exposure to a particular defendant’s product actually caused his cancer, but need only show that the exposure to a particular defendant’s product was a substantial factor in increasing his risk of developing cancer. Id., 16 Cal.4th at 982. In adopting this liberal “substantial factor standard,” the Supreme Court stated that a plaintiff “cannot be expected to prove the scientifically unknown details of carcinogenesis, or trace the unknowable path of a given asbestos fiber”. Id. at 976. Instead, “we can bridge the gap in the humanly knowable” by requiring a plaintiff to show that his exposure to a defendant’s product was a substantial factor in contributing to his aggregate exposure, and thus a substantial factor in increasing his risk of developing cancer. Id. A plaintiff need not demonstrate that exposure to the “fibers of the defendant’s particular product were the ones, or among the ones, that actually produced the malignant growth.” Id. at 977. The Court also explained that “the substantial factor standard is a relatively broad one, requiring only that the contribution of the individual cause be more than negligible or theoretical.” Id., 16 Cal.4th at 978.

Thus, to establish the element of medical causation as to any particular defendant, the Rutherford court held that a plaintiff need only submit evidence that his cumulative exposure to asbestos from all sources was a substantial factor in increasing his risk of developing cancer, and that the contribution of asbestos fibers from a particular defendant’s asbestos-containing products was more than a “merely theoretical or infinitesimal” part of his cumulative exposure to asbestos. The Rutherford court stated that such a liberal medical causation standard was adopted because a plaintiff in a toxic injury action with multiple defendants and products faces the medical and scientific impossibility of identifying which toxins from which specific defendant’s products actually caused his illness:

At the most fundamental level, there is scientific uncertainty regarding the biological mechanisms by which inhalation of certain microscopic fibers of asbestos leads to lung cancer and mesothelioma. . . . An answer to this biological question would be legally relevant, because if each episode of scarring contributes cumulatively to the formation of a tumor or the conditions allowing such formation, each significant exposure by the plaintiff to asbestos fibers would be deemed a cause of the plaintiff's cancer; if, on the other hand, only one fiber or group of fibers actually causes the formation of a tumor, the others would not be legal causes of the plaintiff's injuries.

If, moreover, the question were answered in favor of the latter (single cause) theory, another question-apparently unanswerable-would arise: which particular fiber or fibers actually caused the cancer to begin forming. Because of the irreducible uncertainty of the answer, asbestos-related cancer would, under the single-fiber theory of carcinogenesis, be an example of alternative causation, i.e., a result produced by a single but indeterminable member of a group of possible causes. The disease would thus be analogous to the facts of the hunting accident in Summers, supra, 33 Cal.2d 80.

At the level of abstraction somewhere between the historical question of exposure and the unknown biology of carcinogenesis, the question arises whether the risk of cancer created by a plaintiff’s exposure to a particular asbestos-containing product was significant enough to be considered a legal cause of the disease. Taking into account the length, frequency, proximity and intensity of exposure, the peculiar properties of the individual product, any other potential causes to which the disease could be attributed . . . ., should inhalation of fibers from a particular product be deemed a ‘substantial factor’ in causing cancer? . . . . Plaintiffs cannot be expected to prove scientifically unknown details of carcinogenesis, or trace the unknown path of a given asbestos fiber. . . . [W]e can bridge this gap in the humanly knowable by holding that plaintiffs may prove causation . . . by demonstrating that the plaintiff’s exposure to defendant’s . . . product was a substantial factor in contributing to the aggregate dose . . . the plaintiff inhaled or ingested, and hence the risk of developing asbestos related cancer, without the need to demonstrate that fibers from a defendant’s particular products were the ones, or among the ones, that actually produced the malignant growth. . .

Without such guidance, a juror might well conclude that the plaintiff needed to prove that fibers from the defendant's product were a substantial factor actually contributing to the development of the plaintiff's or decedent's cancer. In many cases, such a burden will be medically impossible to sustain, even with the greatest possible effort by the plaintiff, because of irreducible uncertainty regarding the cellular formation of an asbestos-related cancer. We therefore hold that, in the trial of an asbestos-related cancer case, although no instruction "shifting the burden of proof as to causation" to defendant is warranted, the jury should be told that the plaintiff's or decedent's exposure to a particular product was a substantial factor in causing or bringing about the disease if in reasonable medical probability it contributed to the plaintiff or decedent's risk of developing cancer.

Rutherford v. Owens Illinois, Inc. (1997) 16 Cal.4th at 976-978.

In adopting its liberal causation standard, the Supreme Court explicitly stated that a plaintiff in a toxic injury action need not quantify the dose, level, amount, frequency, or duration of exposure to a defendant’s toxic products to prove exposure or medical causation. Rather, a plaintiff need only submit exposure and causation evidence which permits the jury to reasonably conclude that plaintiff’s exposure to a defendant’s product was a substantial factor in causing his disease, i.e., that such exposure was more than a “merely theoretical or infinitesimal” part of his cumulative exposure to the toxins which increased his risk of developing the disease at issue.

It might also be possible to fashion an instruction that shifted the burden on causation only after the plaintiff had proven, in addition to exposure as such, sufficiently lengthy, intense and frequent exposure as to render the defendant's product a substantial factor contributing to the risk of cancer. As explained earlier, however, there is no need for such a tailored burden shifting instruction; instead, we have determined the jury should simply be told that substantial factor causation can be shown through evidence of exposure to a defendant's product that in reasonable medical probability contributed to the plaintiff or decedent's risk of developing cancer.

Indeed, in stating that a plaintiff is required to show exposure to asbestos from a particular defendant’s product in order to establish medical causation, the Supreme Court cited several California and foreign decisions employing “lenient” and “stringent” exposure standards, none of which require a plaintiff to quantify the dose or level of his asbestos exposure, but rather require a plaintiff to introduce a greater or lesser degree of circumstantial evidence which permits a reasonable inference of exposure to a defendant’s asbestos products.

In conclusion, our general holding is as follows. In the context of a cause of action for asbestos-related latent injuries, the plaintiff must first establish some threshold exposure to the defendant's defective asbestos-containing products (footnote 12), and must further establish in reasonable medical probability that a particular exposure or series of exposures was a "legal cause" of his injury, i.e., a substantial factor in bringing about the injury. In an asbestos-related cancer case, the plaintiff need not prove that fibers from the defendant's product were the ones, or among the ones, that actually began the process of malignant cellular growth. Instead, the plaintiff may meet the burden of proving that exposure to defendant's product was a substantial factor causing the illness by showing that in reasonable medical probability it contributed to the plaintiff or decedent's risk of developing cancer.

. . .

FN12 We do not here endorse any one particular standard for establishing the requisite exposure to a defendant's asbestos products, as the issue has not been raised or briefed in this case. We note that a number of different formulations have been applied, both in the reported California cases, and in federal and sister-state jurisdictions. (See, e.g., Dumin v. Owens- Corning Fiberglas Corp., supra, 28 Cal.App.4th at p. 655 [applying "the most generous application of a lenient causation standard"]; In re Hawaii Federal Asbestos Cases (9th Cir. 1992) 960 F.2d 806, 816-817; Blackston v. Shook & Fletcher Insulation Co. (11th Cir. 1985) 764 F.2d 1480, 1485 [stringent approach requiring particularized proof that the plaintiff came into contact with the defendant's product]; Lockwood v. AC & S Inc. (1987) 109 Wn.2d 235 [744 P.2d 605, 613] [lenient approach; sufficient if plaintiff proves defendant's product was at his or her work site, but resolution depends on particular circumstances of each case].)

Rutherford v. Owens Illinois, Inc. (1997) 16 Cal.4th at 982-983, fn 12.

However, in so holding, the Rutherford court did not indicate whether its liberal causation standard would apply in cases involving toxins other than asbestos or regarding injuries other than asbestos-induced cancer. Subsequently, in Bockrath v. Aldrich Chemical Company (1999) 21 Cal.4th 71, 86, a multi-defendant toxic injury action involving a plaintiff suffering from benzene-induced multiple myeloma (not asbestos-induced cancer), the Supreme Court clarified that Rutherford’s liberal “substantial factor standard” applies in all toxic injury actions involving a single disease caused by exposure to the numerous toxic products of multiple defendants. The Court noted that “[i]n Rutherford . . . we addressed the question of proof of causation in ‘the context of products liability actions.’” Bockrath at 79 (citing Rutherford at 968). The Court then stated that the purpose of the Court’s decision in Bockrath was to set forth how a toxic injury action must be plead to satisfy the elements of proof required under Rutherford’s “substantial factor standard.” The Court held that Rutherford’s “substantial factor standard” applied to plaintiff’s toxic injury action because Mr. Bockrath’s case, as with the asbestos-induced cancer in Rutherford, involved “complicated and possibly esoteric medical causation issues,” i.e., the determination of medical causation when a single disease (e.g., multiple myeloma) is alleged to have been by caused by a plaintiff’s cumulative exposure to toxins (e.g., benzene) from the numerous chemical products (e.g., benzene-containing solvents) of numerous defendants (e.g., the 55 manufacturers and suppliers of said solvents). Id.; see also Whiteley v. Phillip Morris, Inc. (April, 4, 2004), A091444, pages 71-78 (Citing Bockrath as authority for the proposition that the Supreme Court in Bockrath extended Rutherford’s “substantial factor standard [i.e., substantial factor in “increasing the risk” of developing disease] to all toxic injury actions, including a toxic injury action involving lung cancer caused by cigarettes).

According to the Supreme Court, Rutherford’s “substantial factor standard” applies in any toxic injury action in which a plaintiff alleges that her cumulative exposure to toxins from the numerous products of multiple defendants caused her to develop a disease, such as asbestos-induced lung cancer or benzene-induced multiple myeloma. To establish the element of causation in this case as to any particular defendant, a plaintiff therefore only needs to submit direct and/or circumstantial evidence which raises the reasonable inference that his cumulative exposure to the toxin at issue from all sources was a substantial factor in increasing his risk of developing the disease at issue, and that the contribution of such toxin(s) from a particular defendant’s products was more than a “merely theoretical or infinitesimal” part of his cumulative exposure to such toxin(s). In so doing, a plaintiff simply need not quantify the dose or level of his exposure to toxins from defendants’ products, because the Lineaweaver, Sparks, and Rutherford courts have determined that such is an unreasonably stringent exposure/causation standard which a plaintiff suffering from a toxic injury cannot hope to satisfy.

Moreover, several courts from other jurisdictions agree with California’s position that a plaintiff need not quantify dose to prove exposure and medical causation in a toxic injury action. See, e.g., the following:

Amateis v. City of Bridgeport (2000) 2000 Neb.App. Lexis 194 [“We are not prepared to hold that a plaintiff must prove a mathematically precise level of exposure in order to recover in a toxic tort case. Roth-Nelson’s testimony that Anthony was exposed to a sufficiently high concentration to cause his seizures, along with the testimony of the other experts, was sufficient to support the court’s findings regarding proximate cause.”]

Bahura v. S.E.W. Investors (2000) 754 A.2d 928 [One court has held, and we agree, that where there are not facts, such as the exact degree of [plaintiff’s] exposure . . . the experts are still entitled to offer their conclusions based on their areas of expertise, the circumstantial evidence, i.e., [plaintiff’s] health before and after the accident, and the medical tests given [the plaintiff]. The jury is then entitled to attach such weight as it finds [that] the expert testimony deserves. Id., citing Wisner v. Illinois Central Gulf R.R. (La.Ct.App. 1988) 537 SO.2d 740, 748, cert. denied, 540 So.2d 342 (La. 1989).

Bainbridge v. Boise Cascade Plywood Mill (1986) 111 Idaho 79, 721 P.2d 179 [“Boise Cascade urges that Ms. Bainbridge has not presented a prima facie case because NIOSH air quality standards permit formaldehyde levels of up to one part per million and the record provides no evidence indicating that the formaldehyde levels at the situs either reached or exceeded that level. However, to rest its case, as Boise Cascade does at this point, does not negate the prima facie case. The NIOSH standard only sets a parameter for measuring the toxicity of formaldehyde fumes alone. It does not purport to establish a safe level for the combination of formaldehyde and wood particulates. Indeed, Boise Cascade never addressed the issue of whether formaldehyde, at whatever level of concentration in the air, would be absorbed into the wood dust particulates thereby increasing either the concentration of formaldehye or the toxic effect of the combination. Moreover, evidence was presented indicating that highly susceptible individuals could contract such asthma at a level below the NIOSH standard.”]

Clausen v. M/V New Carissa (9th Cir. 2003) 2003 WL 22208783 [“The fact that the minimum threshold level of oil necessary to cause harm to shellfish has not yet been established with any degree of certainty does not render Dr. Elston's evaluation mere guesswork, as the shipowners argue. While ‘precise information concerning the exposure necessary to cause specific harm [is] beneficial, such evidence is not always available, or necessary, to demonstrate that a substance is toxic ... 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] at 264; Heller [v. Shaw Industries, Inc. (3d Cir. 1999) 167 F.3d [146] at 157 (‘even absent hard evidence of the level of exposure to the chemical in question, a medical expert could offer an opinion that the chemical caused plaintiff's illness’).”]

Donaldson v. Central Illinois Public Service Company (2002) 199 Ill.2d 63, 767 N.E.2d 314, 262 Ill.Dec. 854 [“Additionally, we reject CIPS’s assertion that causation includes a showing of exposure, which must be quantified. A Plaintiff must establish that he or she came into contact with chemicals produced by the defendant. See Mitchell v. Gencorp, Inc. 165 F.3d 778, 781 (10th Cir. 1999) [In this context, however, Illinois law does not require that plaintiffs quantify the level of exposure. . . . Environmental exposure cases, like the instant case, do not afford litigants the opportunity to specify with such certainty the exact level and dose of exposure. In most instances, the details of exposure, including information of exactly when or where exposure occurred, is not available. Here, plaintiffs were not required to show the exact amount of exposure. See La Salle National Bank v. Malik, 302 Ill.App.3d 236, 235 Ill.Dec. 755, 705 N.E.2d 938 (1999) (the inability to show the level of exposure did not bar an expert’s opinion); Harris [v. Cropmate Co. (1999)] 302 Ill.App.3d [364] at 371 (discussing causation testimony that did not calculate the concentration of exposure, but instead reached the conclusion that exposure occurred based upon their “generalized knowledge and firsthand experience with and observations of the effects of exposure”)]

Elam v. Alcolac, Inc. (1988) 765 S.W.2d 42, 1988 Mo.App. LEXIS 1546 [“A person subjected to chronic, long-term chemical exposures is not expected to foster a study group in order to prove liability for a disease not even anticipated. . . . This lack of detail of exposure quantitation notwithstanding, the evidence agrees that the plaintiffs were exposed on sufficient occasions, for sufficient durations, in sufficient concentrations to toxic Alcolac chemicals to cause them recurrent [and even chronic] irritations and ailments to their eyes, skin and upper respiratory systems. . . . In this state of the evidence, testimony of the ‘total adverse effects produced by the toxicant when administered continuously over a long period of time’ bears as circumstantial proof of causation.”]

Fulmore v. CSX Transportation, Inc. (2001) 252 Ga.App.884, 557 S.E.2d 64 [“While both analyses involve a question of the concentration levels of the toxin to which the plaintiffs were exposed, it does not necessarily follow that plaintiffs must show specific air measurement readings, or that they have not otherwise established causation.”]

Lewis v. FAG Bearings Corp. (Mo.App. 1999) 5 S.W.3d 579 [“Even where the evidence does not identify the particular chemical at a particular exposure, the particular concentration of the chemical, the particular dosage of the chemical taken in bodily, or the particular duration of the exposures, the identity of the toxic substances to which the harm is attributed may be shown by circumstantial evidence.” Id., citing Elam v. Alcolac, Inc., supra, 765 S.W.2d at 178-179.

Rockwell International v. Turnbull (Colo.App. 1990) 802 P.2d 1182 [“Nor do we agree that the record fails to support Dr. Aldrich’s assumption that claimant was exposed to harmful quantities of toxic chemical substances, including perchloroethylene and 1,1,1-trichloroethane. This assumption is supported by the employer’s acknowledgment that 1,1,1-trichloroethane was used daily in the area where claimant worked. In addition, claimant and a co-worker, both testified regarding workplace exposure to solvents prior to 1978, and to claimant’s virtually “continuous” exposure to a “fog” of a refrigerative coolant that was sometimes rancid with bacterial contamination during his last year of employment. Contrary to the petitioner’s suggestion, lay testimony is sufficient to support a determination of injurious exposure.”]

Spear v. International Business Machines Corp. (Jan 4, 2000) Grand Isle Superior Court Docket NO. S12-4-98 Gicv, State of Vermont, Grand Isle County, SS. Decision and Order: Motion to Exlude Expert Testimony and Motion for Summary Judgment [“Clearly accurate data as to the level of plaintiff’s exposure to TMAH is significant to the formulation of a medical opinion on causation. Inferences, however, can be drawn from the facts surrounding the alleged exposure in this case, including temporal proximity, observations of witnesses, and plaintiff’s reported symptoms. The strength of these inferences goes to the weight of the evidence, not its admissibility.”]

 

4.         A Medical Causation Expert Need Not Rely on Epidemiological Studies to Prove "General Causation"

"Epidemiology is the study of disease occurrence in human populations." Landrigan v. Celotex Corp., 127 N.J. 404, 605 A.2d 1079 (N.J. 1992), citing, Gary D. Friedman, Primer of Epidemiology 1 (3d ed. 1987). "Epidemiology studies the relationship between a disease and a factor suspected of causing the disease, using statistical methods to determine the likelihood of causation." Landrigan v. Celotex Corp., 127 N.J. 404, 605 A.2d 1079 (N.J. 1992), citing, Bert Black & David E. Lilienfeld, Epidemiologic Proof in Toxic Tort Litigation, 52 Fordham L. Review 723, 750 (1984).

"By comparison to the clinical health sciences, which are directly concerned with diseases in particular patients, epidemiology is concerned with the statistical analysis of disease in groups of patients. The statistical associations may become so compelling, as they did in establishing the correlation between asbestos exposure and mesothelioma, that they raise a legitimate implication of causation." Landrigan v. Celotex Corp., 127 N.J. 404, 605 A.2d 1079 (N.J. 1992), citing, Bert Black & David E. Lilienfeld, Epidemiologic Proof in Toxic Tort Litigation, 52 Fordham L. Review 723, 758 (1984). "'Statistical associations,' however, 'do not necessarily imply causation." Landrigan v. Celotex Corp., 127 N.J. 404, 605 A.2d 1079 (N.J. 1992), citing, Friedman, supra, at 182-183. "If the association makes sense in terms of known biological mechanisms or other epidemiologic knowledge, it becomes more plausible as a cause-and-effect relationship." Id.

However, no California case requires a plaintiff to submit epidemiologic evidence to prevail in a toxic tort action. In fact, the only California case addressing the issue holds that a plaintiff need not offer epidemiologic evidence to prove the cause of her disease, when qualified medical experts opine as to causation with the requisite degree of medical certainty. Love v. Wolf, 226 Cal.App.2d 378, 401-402, 38 Cal.Rptr. 183 (1964). A plaintiff is entitled to prove her case by whatever evidence she chooses, including evidence which is entirely circumstantial. "[A] judgment may be based upon inferences drawn from circumstantial evidence, even though there is opposing direct testimony; it is not necessary that the circumstantial evidence in a civil case rise to such a degree of certainty that it excludes every other reasonable conclusion." 3 B. Witkin, California Evidence § 1795 at 1752 (3d ed. 1986); Hasson v. Ford Motor Co., 19 Cal.3d 530, 548, 564 P.2d 857, 138 Cal.Rptr. 705 (1977); Ybarra v. Spangard, 93 Cal.App.2d 43, 46, 208 P.2d 445 (1949); Kerner v. Peacock Dairies, 129 Cal.App. 686, 689, 19 P.2d 283 (1933) [jury could draw inferences from physical facts, such as tire marks, position, and appearance of cars after accident, contrary to direct testimony of eyewitnesses].

Moreover, no California case recognizes “general causation” as an element of proof in a toxic injury action which must be proven by epidemiologic studies or otherwise. Under California law, all aspects of causation are treated as part of the overall determination of the element of causation. Thus, whether a plaintiff elects to prove his case under a theory of independent cause, proximate cause, concurrent cause, alternative cause, multiple cause, or any other theory of causation, the issue to be determined is the same: whether the plaintiff’s exposure to the defendant’s product was a substantial factor in causing his disease, i.e., by increasing his risk of disease by something that is more than merely theoretical or infinitesimal. See Rutherford, supra.

The Supreme Court of Illinois recently issued an opinion in the case of Donaldson v. CIPSC (Ill. Feb. 22, 2002) that is instructive on this point. Donaldson was a toxic tort case in which plaintiffs alleged that environmental exposure to coal tar caused their children to develop neuroblastoma. Neuroblastoma is a very rare cancer of the peripheral nervous system. It is so rare that epidemiologic studies have not been conducted to determine its cause. After denying defendants’ motions for summary judgment based on general causation and refusing to exclude plaintiffs’ experts, a jury verdict was rendered for the plaintiffs. The defendants appealed, arguing that the judgment had to be reversed because of lack of proof of general causation, i.e., absence of publications in the scientific literature concluding that exposure to coal tar causes neuroblastoma. The Illinois Supreme Court affirmed, writing as follows:

We disagree with defendant’s characterization of Illinois law on causation. First, Illinois law does not define causation in terms of “generic” or “specific” causation. Rather, our case law clearly states that in negligence actions, the plaintiff must present evidence of proximate causation, which includes both “cause in fact” and “legal cause.” [citations] A plaintiff may show “cause in fact” under the substantial factor test, showing that the defendant’s conduct was a material element and substantial factor in bringing about the alleged injury.... Donaldson v. CIPSC (Ill. Feb. 22, 2002) at p. 10 of 18.

Since the California Supreme Court has adopted the substantial factor standard and has rejected Daubert, just as did the Illinois Supreme Court in Donaldson, under California law, the mere fact that no articles have been published reporting a causal association between exposure to a particular chemical and a particular disease does not present an insurmountable obstacle to a plaintiff’s proof of causation. In all cases, the issue is whether the plaintiff has offered evidence which establishes causation to a reasonable degree of medical probability. Rutherford, supra.

This principle can be shown by two hypothetical examples, one involving exposure to a chemical resulting in an acute injury and one involving chronic exposure to a toxic chemical resulting in a chronic or latent disease.

Example 1: A worker is given a new chemical to use in his job. The chemical has just been developed by the manufacturer, which has not conducted any tests to determine its toxic effects to humans. The worker, a young man in the prime of life, who exercises, does not smoke, drink or use drugs, and who has always been in excellent health, uses the chemical and within a matter of minutes drops dead. His physician determines the cause of death and rules out all other known causes of the worker’s death. The physician also tests the chemical by administering it to a rat which promptly dies from the same condition suffered by the worker. The physician would like to test the chemical on humans and even conduct an epidemiologic study to determine its “attack rate” on humans, but he cannot ethically do so, even though the manufacturer had no compunction about testing the chemical on the deceased worker. When the worker’s estate sues the chemical manufacturer for wrongful death, defense counsel persuades the court to hold a preliminary hearing on the issue of “general causation.” The defense presents the testimony of multiple well qualified (and well paid) experts, all of whom explain how causality is determined and who opine that in the absence of any published epidemiologic studies reporting a causal association between the chemical and the effect, no “credible causal association” can be made based on “sound science” and conclude that “general causation” therefore cannot be established. Plaintiffs’ counsel concedes that there are no published studies upon which experts can rely to make a causal association. The trial judge finds no general causation and therefore grants judgment for the defendant.

Did the trial court properly conclude that the defendant was entitled to judgment upon determining that there were no published studies upon which an expert could rely to make a causal association between exposure to the chemical and the worker’s death? Under California law, the answer is clearly “no.” Although there was no evidence of “general causation,” plaintiff nevertheless was entitled to have a jury determine his case, because he had expert medical testimony which tended to prove “specific causation,” i.e., that exposure to the chemical in fact caused the plaintiff’s death.

The worker’s physician determined that his patient died upon acute exposure to the chemical. He determined the cause of death and, engaging in the generally accepted method of differential diagnosis, ruled out all other known causes of the injury and the worker’s death. The physician also determined that the chemical was capable of causing the particular toxic effect from which the worker died by reproducing the effect, albeit in an animal model. Although the evidence of causation was hardly strong, the physician’s causation opinion based on differential diagnosis and experimentation was founded on matter reasonably relied upon by qualified experts and was therefore not excludable from evidence. The worker was therefore entitled to have a jury hear his case.

Although the foregoing is an extreme example, it vividly illustrates the fallacy that “general causation” is determinative and shows that litigating this one issue at a preliminary hearing cannot be dispositive of the issue of medical causation and that doing so can result in reversible error under California law.

Example 2: A worker is diagnosed with interstitial lung disease (“ILD”), a chronic lung disease which occurs in the interstitium (the delicate tissue between the air sacs). A textbook notes more than 100 causes of ILD, many of which result from the inhalation of dusts and fumes in the workplace. The worker has been employed in a factory where he is exposed to dusts from a chemical that is not on the list of known causes of ILD. The worker’s physician rules out all other known causes of ILD and is prepared to opine that the worker’s occupational exposure to the chemical caused his ILD. However, the trial judge grants the manufacturer judgment on the basis that no studies have been published reporting a causal association between exposure to the chemical in question and ILD.

Could the plaintiff prove medical causation even in the absence of published literature recognizing a causal association between the chemical and ILD? Of course! To diagnose and treat the worker’s condition, the physician ordered an open lung biopsy which established a diagnosis of ILD. Plaintiffs’ counsel sent a specimen of the worker’s lung tissue to a pathologist who examined it using polarizing light microscopy and who did an in situ analysis of the specimen using scanning electron microscopy (“SEM”). Examination of the worker’s lung tissue revealed birefringent material at fibrotic sites and the material was identified atomically, using SEM, to be the chemical which the worker used on the job and whose dusts he inhaled. Also using SEM, the pathologist determined that the chemical was present in the worker’s lungs at a concentration many times above background. Thus, the cause of the worker’s disease could be proved to a reasonable degree of medical probability despite the unavailability of literature supporting general causation.

What conclusions can be drawn from the foregoing discussion? First and foremost, general causation is not and cannot be determinative of the issue of medical causation in any case. The issue of causation in any toxic tort case always remains whether exposure to the defendant’s product caused the plaintiff’s disease – not whether the chemical is recognized or “generally accepted” as a cause of the disease and not whether published medical literature reports a causal association between the chemical and the disease.

Second, because general causation is not determinative of the issue of medical causation, a court cannot simply grant a defendant judgment if defendant prevails on the issue of general causation, but must nevertheless allow a plaintiff to present his case to the jury on the issue of specific causation, i.e., whether the subject chemical(s) caused disease in the particular plaintiff.

Third, by framing the issue to be whether the medical literature recognizes a causal association between exposure to a chemical and a disease (rather than whether exposure to the chemical caused the plaintiff’s disease), a court improperly elevates publication (which is subject to many biases) above sound science and thereby precludes proof of causation by such generally accepted methodologies as differential diagnosis by qualified physicians, analysis of tissues of the patient by pathologists, ascertainment of biomarkers of exposure and biomarkers of effect – all of which are valid means of proving causation in a particular case.

 

5.         California Courts May Not Determine Whether the Medical Studies Upon Which an Expert Has Relied in Forming Medical Causation Opinions Are "Reliable" or Actually Support the Expert's Opinions

Many courts applying Daubert’s admissibility standards are permitted to scrutinize the medical studies upon which medical causation experts have relied in forming their opinions in order to determine, in the court’s estimation, that such studies are “reliable” and actually support the experts’ opinions. Such is not permitted in California. As recently held in Roberti v. Andy’s Termite & Pest Control, Inc. (2003) 113 Cal.App.4th 893, when determining the existence of a preliminary fact for purposes of determining the admissibility of medical causation opinions, a trial court may only determine those preliminary facts set forth in Evidence Code Sections 801 and 803 concerning the admissibility of expert opinions. Such “preliminary facts” do not include whether a plaintiff’s experts have correctly interpreted and employed the medical studies upon which they have relied when rendering medical causation opinions, or whether the court believes these studies actually support such medical causation opinions.

In Roberti, in support of his theory that Dursban caused plaintiff’s autism, plaintiff presented expert testimony of several toxicologists and medical doctors in which each stated the opinion to a reasonable degree of medical probability that plaintiff's autism was caused by his household exposure to the Dursban (a pesticide) applied by defendant. Plaintiff’s experts based their opinions on plaintiff's medical records, including results of neuropsychological testing, as well as on numerous medical articles in scientific journals, including many animal studies concerning Dursban.

After making its failed Kelly-Frye argument, defendant argued that the testimony of the plaintiff’s medical experts could also be excluded under Evidence Code Section 803, which provides that a trial court "may, and upon objection shall, exclude testimony in the form of an opinion that is based in whole or in significant part on matter that is not a proper basis for such an opinion," because the medical studies relied on by plaintiff’s experts did not support the causation opinions of plaintiff’s experts. 6 Cal.Rptr.3d at 833-834 (emphasis added).

Pursuant to Evidence Code Section 801(b), “[i]f a witness is testifying as an expert, his testimony in the form of an opinion is limited to such an opinion as is: Based on matter (including his special knowledge, skill, experience, training, and education) perceived by or personally known to the witness or made known to him at or before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates . . . .” Pursuant to Evidence Code Sections 801(b) and 803, the only preliminary fact which may properly be determined by the Court concerning the medical studies at issue is whether such studies “[are] of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates . . . .”

As also set forth in People v. Bui (2001) 86 Cal.App.4th 1187, 1196-1197

Thus, pursuant to Roberti, Bui, and other California cases, a trial court’s admissibility determination under Evidence Code Sections 801 and 803 is limited to the general determination that an expert rendering a medical causation opinion (e.g., whether silica causes pulmonary fibrosis) has relied on studies generally concerning the same toxin(s) and category of disease from which the plaintiff is alleged to suffer (e.g., animal studies, cases reports, epidemiologic studies concerning silica and pulmonary fibrosis and other related diseases), because experts rendering similar opinions may reasonably rely on such studies. Unlike courts in Daubert jurisdictions, a California trial court simply may not act as an amateur scientist and scrutinize the medical studies on which an expert has relied when rendering medical causation opinions in order to determine whether a plaintiff’s experts have correctly interpreted and employed the medical studies, whether the court believes these studies actually support such medical causation opinions, or whether such studies are “reliable.” All such determinations are questions of “weight,” rather than admissibility, which may only be determined by the trier of fact.

California’s position was echoed by the Arizona Supreme Court in Logerquist v. McVey (Ariz. 2000) 320 Ariz.Adv.Rep. 15, 1 P.3d 113, in which the court held that the right to jury trial precluded a trial court from applying Daubert principles and determining the reliability of a qualified expert’s opinions as a prerequisite to submission of the expert’s opinions to a jury:

Our constitution preserves the “right to have the jury pass upon questions of fact by determining the credibility of witnesses and the weight of conflicting evidence.” Burton v. Valentine, 60 Ariz. 518, 529, 141 P.2d 847, 851 (1943). The framers’ intent does not contemplate giving judges the power to determine reliability and credibility of a qualified expert as a prerequisite to submission of the expert’s conclusions to a jury for its determination of the weight to the testimony. . . .

It would be strange that a judge forbidden to comment on the reliability or credibility of testimony would be empowered to preclude the jury from hearing the testimony at all because the judge believes it to be unreliable or not worthy of belief. Reduction or obliteration of the jury function may be seen by some as the ultimate tort reform, but it is one prohibited by our organic law. . . .

Questions about the accuracy and reliability of a witness’ factual basis, data, and methods go to the weight and credibility of the witness’ testimony and are questions of fact. The right to jury trial does not turn on the judge’s preliminary assessment of testimonial reliability. It is the jury’s function to determine accuracy, weight, or credibility.

. . .

The Daubert/Joiner/Kumho trilogy of cases . . . puts the judge in the position of passing on the weight or credibility of the expert’s testimony, something we believe crosses the line between the legal task of ruling on the foundation and relevance of evidence and the jury’s function of whom to believe and why, whose testimony to accept, and on what basis.

The court therefore vacated a pretrial ruling in which, after a lengthy hearing, the trial judge determined that the “theories advanced by plaintiff’s experts are not generally accepted in the relevant scientific community,” and directed the trial court to allow the jury to hear the testimony of the plaintiff’s experts and to determine the credibility and weight to which it was entitled.

 

6.         Conclusion

As has been discussed herein, California’s liberal standards concerning the admissibility of expert medical causation opinions in toxic injury actions are quite different that the far stricter admissibility standards employed in federal courts and Daubert jurisdictions. Unlike their counterparts in federal court and Daubert jurisdictions, California trial courts have not been deputized as “gatekeepers” of scientific evidence who have the authority to scrutinize the “reliability” of expert medical opinion in order to exclude such expert evidence from the purview of the trial of fact. Morever, unlike the rules of evidence in federal court and Daubert jurisdictions, California law does not require an exposure or medical causation expert to quantify the plaintiff’s dose to the particular toxin(s) at issue in order to render admissible opinions, and there is also no requirement under California law that an expert’s opinion that a particular toxin is capable of causing a particular disease must be based on epidemiological studies, or that general causation need be satisfied as a distinct element of proof at all.

 

Greg Coolidge is a senior attorney with the Metzger Law Group, a Professional Law Corp. He has litigated many toxic tort cases involving hematologic cancers and lung disease.