Substantial Similarity In Experimental Evidence Under FRE 702 & FRE 403

In defective design litigation, excluding plaintiff's expert testimony regarding an "experiment" that was not sufficiently similar to the conditions and circumstances of the alleged defective grill at the time of the accident; although the expert used an identical device in the same way as the plaintiff did on night of the accident, the experiment crucially differed in placement of a gas tank hose to directly contact heated surfaces, which did not sufficiently replicate conditions at the charged fire; the experiment's identified differences from the undisputed conditions of the grill on the day of the accident were so great as to mislead the jury under FRE 702 and FRE 403 and not helpfully demonstrate applicable general scientific principles, in Dunn v. Nexgrill Industries, Inc., __ F.3d __ (8th Cir. Feb. 25, 2011) (No. 09-2722)

Sometimes expert testimony is proffered in an attempt to recreate the conditions of a device at the time of its alleged malfunction; at other times it is proffered in an attempt to demonstrate general scientific principles -- but how does one distinguish these? In a recent case, the Eighth Circuit explained that:

"'experimental evidence falls on a spectrum and the foundational standard for its admissibility is determined by whether the evidence is closer to simulating the accident or to demonstrating abstract scientific principles.' 'In this case, like many others, the distinction between evidence offered as a reconstruction of the accident and evidence offered to demonstrate scientific principles is very difficult to draw. There is no bright line distinguishing these two categories of evidence.' ‘A court may properly admit experimental evidence if the tests were conducted under conditions substantially similar to the actual conditions.’" "'However, if 'the experimental tests do not purport to recreate the accident, but instead the experiments are used to demonstrate only general scientific principles, the requirement of the substantially similar circumstances no longer applies."
Dunn, __ F.3d at __ (quoting McNight v. Johnson Controls, 36 F.3d 1396, 1401-03 (8th Cir. 1994) (excluding experimental evidence where it was “conducted on the same type and make of battery as the accident battery, and the experiments were used to explain what probably happened during the accident,” and "clearly were not limited to a demonstration of scientific principles in the abstract”) (quoting Champeau v. Fruehauf Corp., 814 F.2d 1271, 1278 (8th Cir. 1987))).


The significance of the case is not that it maps out any new principle of evidence law. The opinion primarily repeats positions taken by the circuit in previous cases, including an agreement with the First Circuit on these principles. However, the case provides an instructive example of distinguishing when an experiment is considered to try to replicate the accident, rather than to demonstrate general scientific principles. In the case, plaintiffs Dunn suffered a house fire apparently when a grill manufactured by defendant Nexgrill exploded. They sought damages from the defendant for defective product design of the grill, alleging that the grill design caused the fire and that the grill 's pressure relief valve "triggered during the fire and released a substantial amount of propane gas, which contributed to the magnitude of fire damage...." Dunn __ F.3d at __.

The district court granted summary judgment for the defendant, after excluding plaintiff's experimental evidence regarding the fire. The trial court found that "the experiment was done to recreate the fire at the Dunns' residence to determine the cause of the fire, not to test scientific principles. The district court also held that the test was not substantially similar to what occurred at the Dunn residence ..., [including a] difference in timelines between [plaintiff's expert] Bicknese's ... test and the fire at the Dunns' home" as the test engulfed the grill in flames after only 50 minutes, while on the night of the accident one hour and 42 minutes passed between the last use of the grill and discovery of the fire. Dunn __ F.3d at __.

On appeal, the plaintiffs claimed that the their expert evidence "was not intended to show how the fire began but was instead intended to show general scientific principles: that is, it was designed to show that the heated grease tray could breach the hose and the then-leaking propane could be ignited by the burner above to cause a fire." Dunn __ F.3d at __. As explained by the expert in testifying about the experiment's results, "the testing was designed 'to establish certain scientific principles' including whether 'the propane hose [could] deteriorate sufficiently to leak when in contact with the grease tray during the grill operation' and whether 'propane leaking from the deteriorated hose can be ignited by the operating burner.' He also testified that his photographs of the burning hose showing it had been compromised by contact with the heated grease tray was 'what happened in this case,' and that the pictures taken during his tests showed what he believed had occurred inside the grill cabinet...." Dunn __ F.3d at __.

The Eighth Circuit rejected this contention and affirmed the trial court's finding that the evidence could be excluded as not sufficiently similar to be admitted as a demonstration of how the accident occurred. According to the circuit:

"The district court's determination that [plaintiff's expert's test] was not just testing scientific principles but instead was trying to recreate the cause and origin of the fire is one that we review for a clear abuse of discretion. Having reviewed the record carefully, we are unable to say that the district court clearly abused its discretion. [Plaintiff's expert] Bricknese did not have to position the propane hose against the grease tray with a tie-down in order to test his theory that a heated grease tray could compromise the hose. Positioning the hose as he did is, in our view, a strong indicator that he was, in fact, trying to recreate how and why the fire happened, and supports the district court's determination. As in McKnight, we find this to be a case 'where some principles of some kind may be demonstrated but in a fashion that looks very much like a recreation of the events that gave rise to the trial.' In McKnight, we relied on the fact that “[t]he experiments were conducted on the same type and make of battery as the accident battery, and the experiments were used to explain what probably happened during the accident,” in holding that the “tests clearly were not limited to a demonstration of scientific principles in the abstract.” Much the same is true here, given the efforts by the Dunns to obtain and use an identical grill for the testing, including cooking food on the grill during the testing, and Bicknese's testimony that the tests and photographs showed “what happened in this case.” As a consequence, in order for the Bicknese evidence to be admissible, the circumstances of the experiments must be “substantially similar” to those existing at the time of the fire."
Dunn, __ F.3d at __ (citing McNight v. Johnson Controls, 36 F.3d 1396, 1402-03 (8th Cir. 1994) ( (quoting Fusco v. Gen. Motors Corp., 11 F.3d 259, 264 n. 5 (1st Cir. 1993)).


The circuit found further evidence that a demonstration of general principles was not intended by the proffer of the expert's evidence because the expert himself testified "that he was really attempting to recreate the fire (as opposed to testing scientific principles), Bicknese himself pointed out dissimilarities between his experiments and the fire, including his removal of the propane tank with its pressure relief valve from the cabinet and his use of a tie-down to secure the hose against the grease tray, conditions that obviously would not have existed in the Dunns' grill at the time of the fire. The district court relied on his 're-routing' of the regulator hose and his use of a 'plastic tie-down' to hold it in what the court called an 'unnatural position' for his experiments in determining the lack of substantial similarity," so that "the lack of substantial similarity would tend to confuse rather than enlighten the jury, a quintessential judgment call committed to a trial judge's sound discretion." Dunn, __ F.3d at __.


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