Opinion ID: 429450
Heading Depth: 2
Heading Rank: 5

Heading: In-Court Demonstration.

Text: 47 During the trial, the court permitted one of the Kehms' experts, Dr. Philip M. Tierno, to perform an in-court demonstration. Dr. Tierno testified that CMC, a component in Rely tampons, can interact with an enzyme found in the vagina, betaglucosidase, to create hospitable conditions for the growth of the Staph A bacteria that produce the TSS toxin. Dr. Tierno illustrated his point in the courtroom by combining, in distilled water, some betaglucosidase with the CMC chips from a Rely tampon. 48 Procter & Gamble contends that the trial court should not have permitted this demonstration, because, it says, Dr. Tierno did not combine the experimental substances in an environment that accurately replicates that of the human vagina. Procter & Gamble argues that even if the demonstration was relevant, it should not have been allowed because it confused and unduly prejudiced the jury. 49 Admissibility of demonstration evidence depends upon a foundational showing of substantial similarity between the tests conducted and what they purport to represent. Ramseyer v. General Motors Corp., 417 F.2d 859, 864 (8th Cir.1969). Procter & Gamble argues that Dr. Tierno's experiment did not meet this foundational requirement because the temperature in the courtroom was different from that in the vagina; he used betaglucosidase obtained from almond pits rather than from the vagina; he placed the enzyme in water rather than in menstrual fluid; and none of the other bacteria, microorganisms, or other substances normally present in the vagina were present in the experimental medium. 50 The trial court rejected Procter & Gamble's arguments on the ground that Dr. Tierno's testimony sufficiently explained the differences between the experimental environment and the actual vaginal environment to allow the jury to reach a reasoned conclusion as to their significance. The court also ruled that the probative value of the demonstration outweighed the danger of prejudice, in view of the ample opportunity Procter & Gamble had to cross-examine Dr. Tierno and rebut his testimony. See Fed.R.Evid. 403. 51 The decision to admit or exclude demonstration evidence rests largely in the discretion of the trial judge. A trial court should use caution in permitting such demonstrations, but the trial court's decision will not be overturned on appeal absent a clear showing of abuse of discretion. Ramseyer v. General Motors Corp., supra, 417 F.2d at 864. Perfect identity between experimental and actual conditions is neither attainable nor required. Id. Dissimilarities affect the weight of the evidence, not its admissibility. Id. 52 In the case at hand, Dr. Tierno testified that the lower courtroom temperature would serve merely to slow the speed of the reaction. He testified that the absence of various vaginal substances from the experimental medium would not affect the desired reaction, and that it was preferred practice in the scientific community to use almond-derived betaglucosidase whenever that enzyme was needed for experimental purposes. We think this testimony established the requisite foundational similarity between the experiment and the actual phenomena it purported to replicate. The trial court did not abuse its discretion in permitting the jury to consider the demonstration, for what it was worth, qualified as it was by both Procter & Gamble's extended cross-examination of Dr. Tierno and the testimony of Procter & Gamble's own expert witnesses. Under the circumstances, we cannot conclude that the demonstration resulted in unfair prejudice to Procter & Gamble. But cf. Randall v. Warnaco, Inc., Hirsch-Weis Div., 677 F.2d 1226, 1234 (8th Cir.1982) (warning of possibility of undue prejudice where jury saw filmed reenactment of tent fire in which plaintiff was injured). 53