August 22, 2019

Tenth Circuit: Disqualification of Expert Testimony Within Sound Discretion of District Court

The Tenth Circuit Court of Appeals issued its opinion in Hall v. Conoco, Inc. on April 10, 2018.

The appeal questioned the causation and exclusion of expert testimony. The district court excluded testimony from two of Hall’s causation experts and granted summary judgment to ConocoPhillips.

The first testimony that was excluded was that of Dr. Gore. Dr. Gore rendered a differential diagnosis for the cause of Ms. Hall’s leukemia. Dr. Gore considered three potential causes: benzene, smoking, and idiopathic (unknown) causes. Dr. Gore stated the cause was benzene because he ruled out smoking. However, he did not expressly rule out the possibility of idiopathic causes.

The district court concluded that Dr. Gore’s differential diagnosis, while an acceptable method for determining cause, was not reliable because he failed to justify benzene as the cause and he failed to rule out “idiopathic causes” for Ms. Hall’s leukemia. This reasoning was in the discretion of the district court.

The Tenth Circuit began its review by assuming, as the district court did, that benzene emissions could have caused Ms. Hall’s acute myeloid leukemia with inverse 16. Ms. Hall bore the burden of proving that benzene emissions from ConocoPhillips actually caused her disease.

One of Ms. Hall’s experts, Dr. Mitchell, created an air model to estimate benzene concentrations near where Ms. Hall had lived. Dr. Gore used Dr. Mitchell’s estimations and the number of years she lived near the refinery to calculate Ms. Hall’s cumulative exposure to benzene. He used this calculation to opine that benzene was the cause of Ms. Hall’s leukemia. The district court, acted within its discretion and identified two flaws with Dr. Gore’s methodology: Dr. Gore could not reliably use the highest hourly average-emission level to calculate Ms. Hall’s cumulative exposure to benzene, and Dr. Gore’s calculation was based on mistakes involving the extent of Ms. Hall’s exposure to benzene.

For the first flaw, Dr. Gore used the highest hourly average-emission level provided by Dr. Mitchell air model, but he did not provide adequate support for using the highest level. Dr. Gore claimed Dr. Mitchell instructed him to use the highest level, but Dr. Mitchell’s testimony states that he was not qualified to determine which level should be used and that the level would best be determined by an oncologist. Dr. Gore did not have any other support for using the highest level, except for his claim that Dr. Mitchell assured him that the highest level was the metric used in the industry.

The district court concluded that neither Dr. Gore nor Dr. Mitchell were qualified to choose the concentration level and that neither could defend the use of the highest hourly average-emission level. Without support for using the highest level of exposure, Dr. Gore’s calculation was questioned, and in turn his ability to rule that benzene was the potential cause was reasonably questioned by the district court. The Tenth Circuit concluded that the district court acted within its discretion relation to the reliability of Dr. Gore’s decisions to use the highest average-emission level.

In the district court’s opinion, Dr. Gore’s omission for ruling out any possible idiopathic causes was a fatal error in the differential diagnosis.

Ms. Hall made the following arguments, which the Tenth Circuit rejected. Ms. Hall argued that the district court misunderstood the concept of “idiopathic” causes. Ms. Hall defined “idiopathic” as a diagnosis by exclusion, meaning only if all known factors are ruled out, leaving no known plausible factors, can the leukemia be considered idiopathic. Using this view, the Tenth Circuit stated that it would be illogical for Dr. Gore to “rule out” idiopathic causes.

Ms. Hall also argued that the Tenth Circuit did not require differential diagnoses to rule out idiopathic causes. The Tenth Circuit Court of Appeals found that the district court could have regarded Dr. Gore’s differential diagnosis as unreliable, and that the district court did not abuse its discretion in excluding Dr. Gore’s opinion based on his differential diagnosis.

In addition to the exclusion of two experts, Ms. Hall also challenged the district court’s granting of summary judgment to ConocoPhillips by arguing that the circumstantial evidence was sufficient to avoid summary judgment. The circumstantial evidence presented by Ms. Hall failed to create a genuine issue of material fact on causation because of the need for expert testimony on the link between her disease and benzene exposure, and quantification of Ms. Hall’s exposure to benzene.

The Tenth Circuit determined that circumstantial evidence was not a sole justification for avoiding a summary judgment. The Circuit determined that Ms. Hall’s theory would require both expert testimony and quantification of her exposure to benzene. Because the expert testimonies of Dr. Gore and Dr. Calvey were excluded, Ms. Hall lacked both of these requirements, and the district court did not err in granting summary judgment to ConocoPhillips on causation.

The Tenth Circuit Court of Appeals upheld the district courts’ exclusion the testimony of Dr. Gore and Dr. Calvey and the summary judgment on causation issued to ConocoPhillips.

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