Barg Coffin Lewis & Trapp, LLP Articles

June 2002

Show Me The Data: A Survey of Evidentiary Issues In Recent Federal Toxic Tort Cases Assessing Medical Causation

By Rick Coffin and Kelly Drumm

I. The Standard For Admitting Expert Opinions -- Daubert And Its Progeny

In toxic tort litigation, a plaintiff's ability to demonstrate a causal inference between exposure and disease rests with the opinions of expert witnesses. The array of scientific approaches available to infer causation range from epidemiological data, to in vitro and animal studies, to chemical structure analysis. A recurrent and pivotal question in all chemical exposure cases is whether the proffered expert testimony concerning medical causation is admissible.

In 1993, the United States Supreme Court settled a long standing split of authority regarding the test for determining the admissibility of expert evidence in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). Specifically, it held that the rigid "general acceptance" test for admitting expert opinions first articulated in Frye v. United States, 293 F. 1013 (1923)¹, had been superceded by the adoption of the Federal Rules of Evidence (FRE) in 1975, specifically FRE 702.²

While affirming the displacement of the Frye "general acceptance" test by FRE 702, the Supreme Court did not prevent trial court judges from screening expert testimony. Rather, it enforced the trial court's "gatekeeping" function to "ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable." Id., at 589.

To guide district courts in assessing the "reliability" of expert testimony, the Supreme Court enumerated the following non-exclusive list of factors to be considered:

"whether a theory or technique…can be (and has been) tested," - that is whether or not the approach can be assessed for reliability;
"whether the theory or technique has been subjected to peer review and publication";
whether there is a "known or potential rate of error…and the existence and maintenance of standards controlling the technique's operation"; and
whether the theory or technique has gained "general acceptance" in the scientific community.

Id., at 593-594.

The Supreme Court was careful to note that these factors, while relevant, are not "a definitive checklist or test." Id., at 593. Moreover, it cautioned that the existence of one or even all of the factors is not dispositive of the reliability of the proffered scientific expert testimony. Id.

In 1997, in General Electric v. Joiner, 522 U.S. 136 (1997), the Supreme Court affirmed Daubert and determined that a deferential abuse-of-discretion standard applies when reviewing district court Daubert decisions. In Joiner, the district court excluded expert testimony based on animal studies proffered to establish a causal link between PCB exposure and small cell lung cancer, finding the studies to be preliminary, and the cancer in the mice to be dose-related and of a type different from plaintiffs'. The Eleventh Circuit reversed, finding the district court had exceeded its authority under the FRE and Daubert by disagreeing with the expert's conclusions rather than evaluating the reliability of the expert's methodologies. The Supreme Court disagreed, noting that:

conclusions and methodology are not entirely distinct from one another. Trained experts commonly extrapolate from existing data. But nothing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence which is connected to existing data only by the ipse dixit of the expert. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered.

Joiner, 522 U.S. at 136.

Then in 1999, the Supreme Court expanded the applicability of Daubert to other forms of expert testimony (e.g. non-scientific) in Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999). The proffered evidence in Kumho was testimony of a tire failure analyst that a manufacture or design defect caused a tire blowout that resulted in a vehicular accident. Applying the Daubert factors, the district court excluded the testimony, finding the analyst's methodology unreliable.

The Eleventh Circuit reversed, believing the district court had erred in applying Daubert to assess the reliability of "non-scientific" evidence. The Supreme Court disagreed, holding that the Daubert factors may also be used to evaluate the reliability of "skill- or experience-based observation" testimony. Kumho, 526 U.S. at 151. Further, it concluded that the district court did not abuse its discretion in finding the expert's methodology unreliable. Id., at 158.

More recently, the Supreme Court revisited Daubert in Weisgram v. Marley Company, 528 U.S. 440 (2000). Applying FRE 702 and Daubert, the district court overruled objections to the admissibility of expert testimony proffered to prove that alleged defects in a heater caused a fire that resulted in plaintiff's mother's death. After a jury verdict in favor of plaintiff, defendant unsuccessfully moved for a judgment as a matter of law on the ground that the expert testimony essential to prove plaintiff's case was unreliable, and thus inadmissible.

The Eighth Circuit reversed, holding that defendant's motion to exclude the expert evidence should have been granted, and concluding that without the expert testimony, plaintiff had insufficient evidence to prove the case. The Supreme Court agreed, and affirmed the Eighth Circuit's denial of plaintiff's request for a new trial under FRE 50(d) on the basis that plaintiff made no attempt to add or substitute evidence, despite being on notice "every step of the way" that the defendant was challenging his experts. Weisgram, 528 U.S. at 456. The Supreme Court explained:

Since Daubert…parties relying on expert evidence have had notice of the exacting standards of reliability such evidence must meet [citations]…It is implausible to suggest, post-Daubert that parties will initially present less than their best expert evidence in the expectation of a second chance should their first try fail.

Id., at 455-456, citing generally Daubert, Kumho, and Joiner.

In sum, these four Supreme Court decisions empower federal district courts with considerable latitude in performing their "gatekeeping" function. Not only do they have wide discretion to make admissibility determinations, but their determinations are afforded great deference on appellate review. Questions regarding reliability -- and admissibility -- of expert disease causation testimony are therefore generally resolved in the district courts. To gauge where district courts have drawn the line on the continuum of available scientific approaches available to demonstrate causal inference between exposure and disease, a survey of recent federal decisions follows.

II. Recent Exposure/Causation Cases In The Federal System³

Edwards v. Safety-Kleen Corporation, 61 F.Supp.2d 1354 (S.D. Florida 1999). Plaintiff alleged that decedent's death (from myelodysplastic syndrome - a bone marrow and blood disease "MDS") was caused by his exposure to benzene. In excluding the expert testimony regarding decedent's benzene exposure levels, the court found that while the formula used by the expert was well-established, his methodology was neither tested nor reliable. Id., at 1358. The court also excluded testimony that decedent's MDS was caused by his benzene exposure because the expert: 1) conceded that an epidemiologic study was required to reliably establish that exposure to benzene caused decedent's MDS, 2) did not know whether the solvents used by decedent contained benzene, and 3) was not aware of any studies which define the minimum level of exposure to benzene necessary to be toxic. Id., at 1358-1359. Lastly, the court excluded defendant's expert testimony that MDS was not caused by benzene exposure because his theory was untested and had no known or acceptable rate of error, had not been subjected to peer review, and was not "generally accepted" in the scientific community. Id., at 1359-1360.
Mitchell v. Gencorp, 165 F.3d 778 (10th Cir. 1999). The Tenth Circuit upheld the district court's exclusion of expert testimony that plaintiff's exposure to xylene, toluene, hexane and haptene caused his chronic myelogenous leukemia ("CML leukemia"). To demonstrate plaintiff's level of exposure, the expert relied upon photographs of the area where plaintiff worked showing chemical spillage and then extrapolated from material safety data sheets. The court found that the lack of objective validation of the expert's technique proved the testimony unreliable. Id., at 781. The court also rejected the expert's attempt to support his conclusions with publications linking exposure to benzene to acute myelogenous leukemia ("AML leukemia"), a type of leukemia different from plaintiff's CML leukemia. The court reasoned 1) plaintiff was not exposed to benzene, and 2) while substantial epidemiological data links benzene to AML leukemia, only the expert's own testimony bridged the gap between AML leukemia and plaintiff's CML leukemia. Id., at 782-783.
Ruff v. Ensign-Bickford Industries, Inc., 168 F.Supp.2d 1271 (D. Utah 2001). Plaintiffs alleged that chemicals from defendant's manufacture of Royal Demolition Explosives (RDX) seeped into their water well and caused them to develop non-Hodgkins lymphoma (NHL). The expert's causation testimony was excluded because the court found the expert's reliance on studies showing that RDX caused liver cancer in mice was not a "scientifically valid" methodology of predicting plaintiffs' NHL. Id., at 1280. However, plaintiffs established that hydrazine and nitrogen (from nitrates) were in the drinking water. When plaintiffs offered causation testimony regarding hydrazine and nitrogen, also based on animal studies, it was found admissible because, unlike the RDX studies, these studies demonstrated a direct correlation between exposure to hydrazine and nitrates and NHL. The court also held that the expert testimony was not required to be supported by epidemiological data showing that exposure to the chemicals caused the specific sub-type of NHL from which plaintiffs suffered. In so holding, the court distinguished Mitchell, supra, finding that "[h]ere, we do not have the benefit of years of epidemiological studies regarding the chemicals from defendant's plant." Id., at 1279.
Daubert v. Merrell Dow Pharmaceuticals, Inc. (Daubert II), 43 F.3d 1311 (9th Cir. 1995). On remand from the Supreme Court, the Ninth Circuit reviewed the district court's exclusion of plaintiffs' expert testimony and subsequent grant of summary judgment under FRE 702 and Daubert. Plaintiffs' experts' testimony of a causal connection between Bendectin exposure and birth defects (deemed inadmissible by the district court under the Frye "general acceptance" standard), was based upon animal studies, chemical structure analysis, and unpublished "reanalysis" of published human statistical studies that had found no causal connection. Plaintiffs' experts did not explain the methodology used to reach their conclusions, did not identify an objective source to show that they followed a scientific method, and their theories of causation had not been subject to peer review. Thus, applying the Daubert reliability factors, the Ninth Circuit held the testimony "inadmissible as a matter of law," reasoning "personal opinion, not science, is testifying here." Daubert II, at 1319.
Kennedy v. Collagen Corporation, 161 F.3d 1226 (9th Cir. 1998), cert. denied, 526 U.S. 1099 (1999). Plaintiff's expert relied on clinical trials, structural analogy between collagen and other materials known to cause autoimmune disorders, and plaintiff's medical records to demonstrate that Zyderm (a bovine collagen used for plastic surgery) caused plaintiff's lupus. In excluding the testimony, the district court emphasized that no epidemiological or animal studies linked Zyderm to lupus. The Ninth Circuit reversed, noting that plaintiff's expert explained that patients who have collagen injections normally return to their plastic surgeons when subsequent problems arise rather than seeking the treatment of a rhumatologist. Thus, "the causal connection goes unrecognized." Id., at 1229. The court also noted that the expert had set forth the steps he took in arriving at his conclusion, and that defendants had not introduced any evidence that the expert's reasoning was not scientifically valid.
Brumbaugh v. Sandoz Pharmaceutical Corporation, 77 F.Supp.2d 1153 (D. Montana 1999). Despite epidemiological reports showing no relationship between ingestion of Parlodel (a lactation prohibitor) and seizures, plaintiff's expert proffered testimony of a causal relationship based on an untested "hypothesis," founded on case reports and adverse drug interaction reports. In excluding the expert testimony, the district court noted that unlike epidemiological data, "[n]either case reports nor adverse drug reaction reports contain scientific analysis with the safeguards of a controlled experiment," and thus they reflect reported data rather than scientific methodology. Id., at 1156.
Grant v. Bristol-Myers Squibb, 97 F.Supp.2d 986 (D. Arizona 2000). The district court excluded expert testimony of a causal connection between breast implants and systemic disease based on differential and clinical studies because the testifying experts had not examined plaintiff and offered no explanation why their "opinions should outweigh the over twenty epidemiological studies finding no valid risk of autoimmune disease resulting from breast implants in humans."
National Bank of Commerce v. Associated Milk Producers, Inc., 191 F.3d 858 (8th Cir. 1999). Applying the deferential standard of review articulated in Joiner, the Eighth Circuit affirmed the district court's exclusion of expert testimony that plaintiff's exposure to a single molecule of aerosolized milk particles containing aflatoxin M-1 ("AFM") may have caused plaintiff's laryngeal cancer. The court reasoned that the following factors supported a determination that the district court did not abuse its discretion: 1) the lack of scientific information as to the level of AFM exposure that would subject a person to an increased risk of cancer, 2) the lack of scientific studies showing a correlation between AFM and laryngeal cancer, 3) the studies upon which the experts relied found no statistical correlation between AFM exposure and laryngeal cancer, and 4) the lack of independent research on AFM exposure by the experts and their failure to examine the plaintiff. Id., at 864.
Glastetter v. Novartis Pharmaceuticals Corp., 252 F.3d 986 (8th Cir. 2001). Plaintiff's experts theorized that plaintiff's strokes were a result of her ingestion of Parlodel because it causes arteries to constrict resulting in elevated blood pressure, which is a recognized risk factor for strokes. In affirming the district court's exclusion of the testimony, the Eighth Circuit noted that the case reports relied upon by plaintiff's experts were not scientifically valid proof of causation, because they lacked analysis, did not screen out alternative causes of strokes, and often omitted relevant facts. Id., at 989. The court also found the expert's reliance on several medical texts unpersuasive because they were grounded in case reports and "generic comparisons" between the active ingredient in Parlodel and related chemical compounds, or concluded that diseases other than stroke were caused by Parlodel. Id., at 990. Lastly, while noting that the experts' "rechallenge and dechallenge data"⁴ was "more potent proof of causation than the district court believed it to be," it found no abuse of discretion in finding it unreliable. Id., at 990-991.
Nelson v. Tennessee Gas Pipeline Company, 243 F.3d 244 (6th Cir. 2001). Plaintiffs' expert proffered testimony that PCB exposure from defendant's plant caused plaintiffs' illnesses based on his comparative study of 98 people (including 7 plaintiffs) from Lobelville (the location of the plant), and a control group of 58 people from other communities. The district court concluded that the expert's study failed to 1) account for "confounding factors" that could have caused similar symptoms, 2) establish a temporal relationship between exposure to PCBs in Lobelville and the reported illnesses, 3) demonstrate that plaintiffs' exposure to PCBs was sufficient to cause the illnesses, and 4) establish that his theories were "generally accepted." Id., at 252. Due to these flaws in the methodology underlying the expert's opinion, the Sixth Circuit affirmed the district court's exclusion of the expert opinion. Id.
Curtis v. M&S Petroleum, Inc., 174 F.3d 661 (5th Cir. 1999). The district court found that scientific publications and temporal analyses supported the expert's conclusions that an exposure to benzene at 200-300 ppm would cause plaintiffs' headaches, nausea, dizziness, diarrhea and lack of energy. However, it determined the expert's causation testimony inadmissible for failure to establish plaintiffs' exposure levels to benzene. Id., at 669. The Fifth Circuit, while recognizing that establishing exposure level is one of the "minimum facts" necessary to prove causation in a toxic tort case, concluded that "the law does not require Plaintiffs to show the precise level of benzene to which they were exposed." Id., at 671. Thus, because the expert's testimony was supported by evidence that plaintiffs' symptoms were consistent with an exposure to high levels of benzene, the alleged level of exposure was probable, and the testimony admissible. Id.
Westberry v. Gislaved Gummi AB, 178 F.3d 257 (4th Cir. 1999). Defendant challenged the reliability of expert testimony of a causal link between airborne talc exposure and plaintiff's sinus disease, arguing that the expert had no epidemiological studies, no peer-reviewed published studies, no animal studies, no laboratory data and no other evidence that talc exposure causes sinus disease. Id., at 261. Instead, plaintiff's expert relied on temporal studies and differential diagnosis in reaching his causation conclusions.⁵ In finding the testimony admissible, the Fourth Circuit noted that differential diagnosis has "widespread acceptance in the medical community, has been subject to peer review, and does not frequently lead to incorrect results." Id., at 263. It also noted that "the overwhelming majority of the courts of appeal that have addressed the issue have held that a medical opinion on causation based upon a reliable differential diagnosis is sufficiently valid to satisfy the first prong of the Rule 702 inquiry." Id.⁶ Thus, because the expert's methodology was found to be reliable, the testimony was admissible.
Heller v. Shaw Industries, Inc., 167 F.3d 146 (3rd Cir. 1998). To demonstrate a causal link between exposure to VOCs and plaintiffs' respiratory illness, plaintiff's expert relied on a differential diagnosis and temporal relationship analyses. The district court excluded the testimony primarily because the expert cited "no research" in support of his conclusion that the VOC levels detected in plaintiff's house could and did cause her injuries. Id., at 154. The Third Circuit disagreed, finding Rule 702 does not require research studies to support a finding of causation. It noted, however, that "it was not necessarily error to exclude Dr. Papano's causation conclusion as unreliable if he relied on no scientific studies and the remaining foundation for his conclusion was shaky." Id., at 155. The Third Circuit also determined that the district court had erred in finding the expert's differential diagnosis inadequate for failing to "rule out all alternative possible causes" of plaintiff's illness. Id., at 156. However, because the expert's temporal relationship analysis (upon which the expert "heavily" relied to establish causation) was flawed, the Court of Appeal affirmed the exclusion of the expert opinion. Id. at 158.
Sutera v. Perrier Group of America, Inc., 986 F.Supp.2d 655 (D. Mass. 1997). Plaintiff alleged that his consumption of mineral water caused him to contract APL leukemia because it was contaminated with low levels of benzene. To support this allegation, plaintiff's expert relied on three epidemiological studies and a risk-assessment theory that there is no safe exposure level to benzene. In excluding the expert causation testimony, the court noted that all of the epidemiological studies involved subjects whose exposure to benzene was through inhalation, and the dosage and duration of the exposure was "substantially greater in order of magnitude" than plaintiff's. Id., 662-663. It also found the studies unreliable because they do not "explore the exposure necessary to trigger the cancer-producing mechanism." Id., at 663. Lastly, the court found the expert's risk assessment approach inappropriate because there was no scientific evidence that it was an acceptable scientific technique for determining causation. Id., at 663-665.

III. Recent Amendments To Evidence Code §702

As amended in December 2000 in response to the Supreme Court decisions in Daubert and Kumho, FRE 702⁷ provides:

"If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based on scientific facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case."

According to the 2000 Advisory Committee Notes following FRE 702, the amendment affirms the trial court's role as evidentiary "gatekeeper" envisioned by the Supreme Court in Daubert, and Kumho's holding that the gatekeeper function applies to all expert testimony. Yet, while "[n]o attempt has been made to 'codify' these [Daubert] factors," the Advisory Committee notes that the amendment provides "some general standards that the trial court must use to assess the reliability and helpfulness of proffered expert testimony." FRE 702, 2000 Advisory Committee Notes (emphasis added); see also Dhillon v. Crown Controls Corporation, 269 F.3d 865, 869 (7th Cir. 2001).

By mandating an inquiry into the sufficiency of the basis, method and reliability of the expert testimony, amended FRE 702 requires an analysis that was not expressly made part of the admissibility analysis articulated in Daubert. FRE 702(2) and (3); see also Rudd v. General Motors Corporation, 127 F.Supp.2d 1330, 1335 (M.D. Ala. 2001). However, the Advisory Committee cautions the amendment:

is not intended to authorize a trial court to exclude an expert's testimony on the ground that the court believes one version of the facts and not the other…[T]he rejection of expert testimony is the exception rather than the rule. Daubert did not work a seachange over federal evidence law, and the trial court's role as gatekeeper is not intended to serve as a replacement for the adversary system. Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.

FRE 702, 2000 Advisory Committee Notes (internal citations and quotations omitted); see also Allstate Insurance Co. v. Hugh Cole Builder, Inc., 137 F.Supp.2d 1283, 1286 (M.D.Ala.2001), (quoting Rule 702 Advisory Committee Notes, 2000 amendment).

Thus, while FRE 702 (as amended) now expressly requires courts to consider the reliability of the expert's methodology, it was not intended to effect a departure from Daubert or its progeny. Amorganianos v. National Railroad Passenger Corporation, 137 F.Supp.2d 147, 162 (E.D.N.Y. 2001); Nelson v. Tennessee Gas Pipeline Co., 243 F.3d 244, 250 n. 4 (6th. Cir. 2001) (held that the amendment did not alter the standard for evaluating the admissibility of experts' opinions as articulated in those cases); Cooper v. Smith & Nephew, Inc., 259 F.3d 194 (4th Cir. 2001). As a result, "post-Daubert, pre-amendment case law construing Rule 702 remains fully applicable" to trial court expert reliability determinations. Amorganianos, 137 F.Supp.2d at 162.

IV. Evidence Code §706 And The Use Of Court Appointed Special Masters

Opposing experts in litigation are hired and paid to present contradictory opinions. Thus, in some instances, a court appointed expert witness may be useful in providing information regarding technical issues, methodology, background information to aid comprehension, or to offer a neutral opinion on a disputed technical issue. Pursuant to FRE 706, the federal courts have broad discretion to order the appointment of such an expert. FRE 706(a).

Procedurally, the court, sua sponte, or any party may "enter an order to show cause why expert witnesses should not be appointed, and may request the parties to submit nominations." FRE 706(a). However, the court is not limited to experts recommended by the parties, but may appoint an expert of its own selection. Id.

The court also has discretion to determine whether the jury should be instructed that the expert is court appointed. FRE 706(c). However, FRE 706 cannot be used to compel an expert to testify without his consent, and without the provision of "reasonable compensation" in an amount determined by the court. FRE 706(a) and (b).

While the appointment of an independent expert witness may appear useful, it is not without pitfalls, including:

additional expense to the parties;
the difficulty in finding a truly "neutral" expert, as he or she will undoubtedly have had past experience which may bias the expert's opinion in favor of one side over the other;
the risk that the jury will perceive the court as "taking sides," if it chooses to disclose the appointment to the jury; and
trial delay.

Thus, prior to moving for, or acquiescing to, a motion for the appointment of an independent expert, serious consideration should be given to alternatives, such as directing the existing witnesses to clarify or simplify their testimony, or narrow and define the differences in the experts' opinion. For a comprehensive discussion on the use of court appointed independent experts, see D. F. Herr, Annotated Manual for Complex Litigation (West Group), 3rd. ed.. 2001, §21.51, pp. 123-124, and J.S. Cecil and T.E. Willging, Court Appointed Experts: Defining the Role of Experts Appointed Under Federal Rule of Evidence 706 (Federal Judicial Center 1993).

Endnotes

In Frye, a systolic blood pressure deception test was held to be unreliable and thus inadmissible at trial. The court explained, "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." Id., at 1014.
When the Supreme Court decided Daubert, FRE 702 provided:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
This paper does not attempt to review every recent trial and appellate court opinion addressing exposure/causation evidence in the federal system. Instead, it provides a sampling from a majority of the federal circuits to give an overview of how the exposure/causation evidence is being addressed.
Rechallenge occurs when a doctor exposes a patient to a drug believed to have caused an earlier adverse reaction; dechallenge removes that exposure. Glastetter, 252 F.3d at 990.
Differential diagnosis or etiology is a "standard scientific technique of identifying the cause of a medical problem by eliminating the likely causes until the most probable one is isolated." Westberry, 178 F.3d at 261.
For other cases in which differential diagnosis has been found reliable to infer causation, see, Kennedy v. Collagen Corp., supra, 161 F.3d at 1228-1230, Zuchowicz v. United States, 140 F.3d 381 (2d Cir. 1998), Ambrosini v. Labarraque, 101 F.3d 129, 140-141, (D.C. Cir. 1996), Baker v. Dalkon Shield Claimants Trust, 156 F.3d 248, 252-253 (1st Cir. 1998).
The underscored portions of the FRE 702 were added by the 2000 amendments. No other amendments to rule were made.

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Posted with permission from American Bar Association Tort and Insurance Practice Section 11th Annual Spring CLE Meeting, March 2002; Phoenix, Arizona

These materials are provided for information purposes only and are not intended as and cannot be considered legal advice. Before taking action based upon this information, you should consult your legal counsel.

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