Recently, the Delaware Supreme Court decided Tumlinson v. Advanced Micro Devices, Inc., No. 672, 2012 (Del. Nov. 21, 2013). This case provides a great example of the so-called “gatekeeper” function of the court when it comes to the admission of expert testimony in civil cases. More importantly, it provides context concerning the admissibility of expert epidemiological testimony under the Daubert standard in products liability cases. In Tumlinson, the Supreme Court affirmed a decision of the trial court that excluded an epidemiologist’s expert testimony on the ground that it failed to satisfy the reliability requirements of Delaware Rule of Evidence 702 and Del. R. Evid. 702.

The Facts

The defendant, Advanced Micro Devices, Inc. (“AMD”), a Delaware corporation with offices in several major U.S. and global cities, manufactures semiconductors used in computers. In 2008, the plaintiffs, who worked in AMD’s plants, filed suit against AMD based on their theory that chemicals used in the manufacture of AMD’s semiconductors caused birth defects in their children.

To support their claims, the plaintiffs retained an expert epidemiologist who concluded that the chemicals allegedly present in the AMD plant caused their children’s birth defects. AMD filed a motion in limine, wherein it argued that the epidemiologist’s opinion was unreliable because too many analytical gaps existed in her methodology to render a sound opinion. The trial court agreed.

Daubert Factor #1: Whether the expert’s opinion can be (and has been) tested.

The trial court first found that the expert’s opinion could not be tested because it lacked sufficient specificity. In this case, each of the plaintiffs’ children suffered birth defects that were very different in nature. The court observed that the epidemiologist was unable to identify which specific chemical or combination of chemicals caused the children’s different birth defects. The court further found that the expert did not distinguish between the differing work environments between the two plaintiffs or consider, specifically, how these different environments may have impacted the level of exposure.

Daubert Factor # 2: Whether the expert’s method has been subject to peer review and publication.

The court next considered whether the expert’s methods were subject to peer review and publication. The plaintiffs’ counsel argued that the expert’s opinion was peer reviewed because it was based on three studies that the expert synthesized before formulating her own conclusion. The court ruled that an expert’s opinion, even if based on the synthesis of peer reviewed studies, must demonstrate an independent indicia of reliability. The court found that there was nothing in the record to provide this independent reliability and, furthermore, the studies cited by the expert were produced in the context of other litigation and, themselves, unreliable.

Daubert Factor #3: Whether the methodology has attracted widespread acceptance within a relevant scientific community.

Finally, the trial court found that the epidemiologist failed to demonstrate that she relied on techniques that have gained acceptance in the scientific community. In reaching this conclusion, the court first observed that there are multiple scientific approaches that epidemiologists use to establish causation. Turning to the expert’s opinion, the court then found that she did not demonstrate that her opinion was the product of any of these accepted approaches. Specifically, the expert failed to detail her method of weighing the importance and validity of the data sources she used to form her opinion.

Take-Away:

When assessing the validity of an expert report, it is important to consider the factors highlighted above: does the report sufficiently state the scientific method used? Is the opinion based on reliable, peer reviewed sources? Does the expert consider objective data? Has the expert set forth each analytical step toward reaching his or her conclusion or has the expert ignored any consideration that might alter the opinion? As this lower court’s opinion and its affirmance by the Delaware Supreme Court demonstrate, the answers to these questions may determine the fate of your clients in complex product liability litigation.