Expert Witness Testimony: The Difference Between Testing Scientific Principles and Determining Cause

We can’t resist writing about recent judicial opinions in which a Plaintiffs’ expert is excluded, and last month, the Eighth Circuit affirmed a lower court’s decision to do just that. In Dunn v. Nexgrill Industries, Inc., —F.3d —, 2011 WL 668062 (8th Cir. Feb. 25, 2011) [PDF], the Eighth Circuit considered whether the trial court abused its discretion when excluding the testimony of an expert witness as well as the trial court’s granting of the defendant’s summary judgment motion. In so doing, the Eighth Circuit held that 1) the district court did not abuse its discretion in excluding the Plaintiffs’ expert’s testimony, and 2) that without the expert testimony, the plaintiffs could not establish that the grill was unreasonably dangerous or defective. As a result, the Court affirmed the trial court’s rulings.

Thomas and Thelma Dunn filed a complaint against Nexgrill Industries, Inc., the designer, manufacturer, and seller of a propane grill they claim caused a fire at their home. They claimed that the grill was defectively designed, such that the grease tray came into contact with the rubber regulator hose, which melted and allowed propane gas vapors to escape and ignite.

To prove their case, the Dunns presented the testimony of purported expert Randy Bicknese. He attended the initial investigation into the cause and origin of the fire, which determined that the fire originated in the bottom cabinet of the grill and was caused by the escape of propane gas from the fuel delivery system. Bicknese also conducted additional tests by using a used grill of the same make and model, since the specific grill at issue was no longer manufactured. In his affidavit, Bicknese stated that the purpose of the testing was as follows:

. . . to establish certain scientific principles: (1) to determine whether or not the propane hose can deteriorate sufficiently to leak when in contact with the grease tray during grill operation; (2) to determine if propane leaking from the deteriorated hose can be ignited by the operating burner; (3) to determine if a propane hose fire in the cabinet can be sustained after the burner controls are turned off; (4) to determine if a propane hose fire in the cabinet is readily detectable from outside the grill with the grill lid open and the cabinet door closed; (5) to document the operating characteristics of the grill’s propane distributing system; (6) to determine the consumption rate of the propane hose as a result of the ignited leak.

Bicknese also performed a subsequent round of testing, after which he reported that “the second test continued to support his theory that the fire was the result of the deterioration of the rubber propane hose caused by contact with the heated grease tray.”

Nexgrill filed a motion to exclude Bicknese’s testimony and testing, which was granted because in the opinion of the district court the testing “was done to recreate the fire at the Dunns‘ residence to determine the cause of the fire, not to test scientific principles.” The court further concluded that the test was not substantially similar to what happened during the fire at the Dunns‘ house. After the court excluded Bicknese’s evidence, Nexgrill filed a motion for summary judgment, which was also granted.

The Eighth Circuit affirmed the ruling, finding that the district court had not abused its discretion. As that court noted, “The Dunns‘ main argument is that the tests were conducted to test scientific principles and Bicknese’s hypothesis, not to show exactly how the accident occurred.” Although the line between these two testing principles is “very difficult to draw,” the Eighth Circuit determined that it was unable to say that the lower court abused its discretion.

Without expert testimony, the Dunns were in a real pickle in terms of proving that the grill was actually defective. They tried the only route they had left: they argued that they should be allowed to present circumstantial evidence of the products defect, despite the fact that they failed to plead res ipsa in their complaint. The Eighth Circuit prohibited this type of proof not only because of the improper pleading, but also because “grills are designed specifically to ignite,” and therefore, the fact that the grill actually ignited did not prove a defect. As a result, the Eighth Circuit affirmed summary judgment for Nexgrill.

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