Before Daubert, district courts were faced with a relatively simple inquiry in deciding whether an expert could testify: Was the expert's theory generally accepted in the relevant scientific community? Following Daubert, more than a few courts were reluctant to vigorously defend the witness box against questionable expert testimony, primarily for two reasons.
First, a number of commentators suggested that Daubert actually represented a liberalization of the standards respecting expert testimony and spoke disapprovingly of "rigid" views that excluded too much expert testimony. Second, some judges were reluctant to engage in consideration of the Daubert factors – such as whether the expert's theory had a known rate of error within acceptable parameters – out of concern that Daubert unfairly required them to have expertise in the scientific method that their legal background did not provide.
The message of Kumho Tire, however, is that the federal courts have an unmistakable duty to guard the evidentiary gate where expert witnesses are concerned.
Kumho Tire involved a product-liability claim against a tire manufacturer following a vehicle accident. The tire manufacturer succeeded in obtaining summary judgment after arguing that the plaintiff's expert witness was unqualified under Daubert to testify about alleged defects in the tire and whether they caused the accident.
The plaintiff's expert was not a traditional laboratory scientist, but an engineer who had worked for another tire manufacturer before becoming an expert witness in tort cases. Although the expert's testimony was that his visual and tactile inspection of the tire led him to conclude that a defect in the tire caused it to ultimately fail, the Supreme Court rejected the testimony under the test it first set out in Daubert for evaluating traditional scientific evidence.
There were many reasons why the expert's methodology gave the court pause. For example, the expert concluded that a defect had caused the tire failure despite evidence that the tire had two punctures that had been inadequately repaired, the tread had worn bald and the tire showed signs of abuse and should have been taken out of service. Moreover, the expert used a methodology that was admittedly "subjective," had inspected the tire once just prior to his deposition and admitted that he had not examined many similar tires, even while he maintained that the identification of tire defects depended on familiarity with "a lot" of similar tires. Finally, there was no evidence that the expert's subjective methodology was generally accepted by tire engineers.
After evaluating the factors first set forth in Daubert and concluding that each militated against admitting the expert's testimony, and after concluding that no new factors supported admissibility either, the trial court determined the expert should be excluded, and the Supreme Court affirmed.
The foremost principle set forth in Kumho Tire is the importance of "gatekeeping" – the district courts' duty to ensure that evidence presented to juries by expert witnesses is both relevant and reliable – whether an expert is offered to opine on scientific matter or matters that fall outside of traditional laboratory study.
Kumho Tire also explains that the list of criteria in Daubert for the evaluation of expert testimony is flexible. In Daubert, the court evaluated the relevance and reliability of the expert's scientific evidence by looking at whether the expert's theory was testable and had been subject to peer review or publication; whether there was an acceptable known error rate for the theory; and whether the theory was well accepted in the relevant scientific community.
These Daubert factors, the Kumho Tire court noted, "may" be used in evaluating "technical or other specialized knowledge" as well as scientific evidence. On the other hand, the Daubert factors were meant to be "helpful, but not definitive," leaving district courts to consider other indicia of reliability more suited to the specific circumstances of the cases before them.
Justice Antonin Scalia penned a one-paragraph concurrence on this point and was joined by Justices Sandra Day O'Connor and Clarence Thomas. He noted that a district court's discretion in evaluating the relevance and reliability of expert testimony is the "discretion to choose among reasonable means of excluding expertise that is fausse and science that is junky" – it is not discretion "to abandon the gatekeeping function."
This concurrence intimates that future cases may be closely reviewed for appropriate application of Daubert factors, warning that "in a particular case the failure to apply one or another [of the Daubert factors] may be unreasonable and hence an abuse of discretion."
The final key point of Kumho Tire is that in fulfilling the gatekeeping duty to exclude irrelevant or unreliable expert testimony, district judges have the discretion to "decide when special briefing or other proceedings are needed to investigate reliability. … In certain cases, it will be appropriate for the trial judge to ask" for the error rate of a theory or whether it is generally accepted in the relevant expert community.
Accordingly, even though the district court in Kumho Tire excluded the expert on the briefs and written materials filed by the parties, it could have exercised its discretion to hold a hearing pursuant to Federal Rule of Evidence 104, or perhaps designed some other creative procedure in the manner of Judge Robert E. Jones of the District of Oregon. See, e.g., Hall v. Baxter Healthcare Corp., 947 F.Supp. 1387 (D. Or. 1996) (to determine whether plaintiffs' experts should be permitted to testify that silicone breast implants caused "atypical connective tissue disease," district court appointed independent scientific advisers and held hearings at which advisers were permitted to question the plaintiffs' experts).
Kumho Tire's clear casting of the trial judge in the role of gatekeeper, combined with the court's flexibility to investigate the relevance and reliability of expert testimony, at a minimum, allows judges the discretion to initiate inquiry into these issues if the parties have not submitted evidence sufficient to permit the court to evaluate the expert's admissibility.
Arguably, the combination of the clear gatekeeping duty and the discretion to use special procedures imposes a further duty on the court to independently satisfy itself that each expert is qualified and will offer relevant and reliable opinions – even if the parties have not raised the issue.
In the limited time since Kumho Tire was issued, it appears that the circuit courts have embraced that message.
Ð The 5th U.S. Circuit Court of Appeals has reversed plaintiffs' verdicts in two cases, concluding that expert testimony had been improperly admitted at the trial of each. See Black v. Food Lion Inc., 1999 WL 173001 (5th Cir. Mar. 30, 1999) (physician's opinion that plaintiff developed autoimmune disease fibromyalgia after "slip and fall" accident in grocery store was inadmissible absent evidence that science knows the exact process that results in fibromyalgia or factors that trigger the process, no "scientifically reliable conclusion on causation" could be drawn by expert); Tanner v. Westbrook, 1999 WL 246712 (5th Cir. April 27, 1999) (in medical-malpractice action, even though physician relied on articles that stated that asphyxia can cause cerebral palsy as general proposition, his testimony on causation should have been excluded because physician did not have sufficient expertise or foundation for testifying that asphyxia caused this plaintiff's cerebral palsy).
Ð The 8th Circuit affirmed the exclusion of an expert whose opinion was deemed unreliable. Jaurequi v. Carter Mfg. Co. Inc., 1999 WL 185046 (8th Cir. April 6, 1999) held that the plaintiff's mechanical engineer and "human factors expert" was properly excluded where his opinion on alleged warning and design defects in a John Deere tractor was marred by contradictions in his testimony and assumptions and conclusions that lacked foundation.
In light of the Supreme Court's ringing re-endorsement of the Daubert framework in Kumho Tire, the most fascinating question for the future is whether California's Supreme Court will adopt the Daubert/Kumho Tire analysis the next time it addresses expert admissibility, or whether California's Legislature will see fit to do so itself.
In a post-Kumho Tire world, proponents of experts with cutting-edge theories or questionable logic should be prepared for a more searching inquiry by the district court, regardless of whether the expert is a traditional scientist or some other type of expert.