Academic journal article Defense Counsel Journal

Daubert, Doctors and Differential Diagnosis: Treating Medical Causation Testimony as Evidence

Academic journal article Defense Counsel Journal

Daubert, Doctors and Differential Diagnosis: Treating Medical Causation Testimony as Evidence

Article excerpt

An assessment of admissibility is not the same as an assessment of sufficiency, but Daubert has created that confusion

CAROL HELLER began experiencing various respiratory problems shortly after Shaw Industries installed new carpeting in her house.(1) A few months later, she consulted an allergist, Dr. Joseph Papano. He took her medical and family

histories, questioned her about the house's environment, ordered chest x-rays, and performed several laboratory tests. Based on his findings from the collected data, Dr. Papano ruled out various possible causes of Heller's respiratory problems. This winnowing process, known as "differential diagnosis" in the medical community, coupled with the close temporal relationship between Heller's symptoms and the installation of the new carpet, led Dr. Papano to conclude that the carpet was the cause of her illness.

Heller sued Shaw Industries for, among other things, failure to warn and defective design. She called Dr. Papano as an expert witness to testify on the issue of causation, but the trial court excluded his testimony. The problem: Although Dr. Papano conducted a differential diagnosis to determine what did not cause Heller's symptoms, he could point to no studies indicating that the carpet could cause them. Without this testimony, Heller could not prove causation, and the court granted summary judgment in favor of Shaw.

The Third Circuit, while disagreeing with some of the trial court's rationale, affirmed both the exclusion of Dr. Papano's testimony and summary disposition in favor of Shaw.


The Heller case reveals one of the central problems underlying most mass and toxic tort litigation--proving that the defendant's product caused the plaintiff's injury. As is the case with other torts, the plaintiff in a mass or toxic tort case must show duty, negligence, causation and damage. In the mass or toxic tort context, however, the element of causation often plays a dispositive role. Plaintiffs must prove both that the product is capable of producing the injuries (general causation) and that the product actually did so (specific causation).(2) To do so, they must rely on the testimony of experts--toxicologists, engineers, physicians--with scientific and technical knowledge of the product in question and its effects on the human body. If the testimony of these experts is either inadmissible or insufficient to carry the burden of proof, plaintiffs' cases cannot go forward. Accordingly, the admissibility and sufficiency of the expert testimony often becomes a hotly contested issue.

Inherent in ruling on the admissibility of expert testimony is that courts must review the underlying science to determine the reliability and relevance of the evidence. For 70 years, the "general acceptance" test from Frye v. United States(3) enjoyed almost uniform application in both state and federal courts.(4) This test admitted scientific evidence if, and only if, it was generally accepted in the pertinent scientific community. Under Frye, courts looked deferentially to scientists in determining whether the proffered evidence met the standards of scientific reliability.

This era of deference came to an end with the Supreme Court's decision in Daubert v. Merrell Dow Pharmaceuticals Inc.,(5) which interpreted Federal Rule of Evidence 702 as superseding the common law "general acceptance" test. The Court read Rule 702 as establishing a system wherein federal trial judges ensure the reliability, as well as the relevance, of scientific testimony.

Trial judges must serve as "gatekeepers" when it comes to scientific evidence, assessing the methodologies underlying the testimony of expert witnesses. Trial judges must review and screen evidence based on everything from aerodynamics to epidemiology. The "gatekeeper" role was reaffirmed in General Electric Co. v. Joiner(6) and Kumho Tire Co. v. Carmichael.(7)

A source of scientific evidence in mass and toxic tort litigation is the medical technique called differential diagnosis. …

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