Section 8.8 Inspections, Tests, and Experiments

• Library: Sources of Proof (2014 Ed.)

B. (§8.8) Inspections, Tests, and Experiments

Experimental evidence can add believability that may be lacking from the mere testimonial assertion of certain factual conclusions. The evidence in most instances would need to be presented by an expert witness, though a lay witness can testify as to what the lay witness sees, hears, feels, tastes, and smells. Roy v. Mo. Pac. R.R. Co., 43 S.W.3d 351, 359 (Mo. App. W.D. 2001).

Counsel should give specific consideration to the purpose for which the tests or experiments are conducted and offered in evidence. If the purpose is directed toward proof of causation of a particular event, a showing of substantial similarity between the test conditions and actual conditions is mandatory. Substantial similarity, however, does not require a showing of identical conditions. See:

• Hawkins v. Scott’s Gas of Lowry City, Inc., 685 S.W.2d 247, 249 (Mo. App. S.D. 1985) (approving testing for the presence of moisture vapor in propane tanks two years after a fire when there was testimony of no significant change in the tank’s condition in the interim)

• Blevins v. Cushman Motors, 551 S.W.2d 602, 609 (Mo. banc 1977) (approving evidence relating to the propensity of a golf cart to overturn even though the test involved a different model golf cart, anthropometric dummies rather than human passengers, and turning mechanisms activated by remote control)

The proponent of experimental evidence has the burden of presenting a foundation showing that the test, in material aspects, has the requisite similarity to the conditions or occurrences at issue in the suit. Porter v. Erickson Transp. Corp., 851 S.W.2d 725, 739 (Mo. App. S.D. 1993). This is frequently done via deposition of the individual conducting the testing, as in Embree v. Norfolk & Western Railway Co., 907 S.W.2d 319, 325 (Mo. App. E.D. 1995).

In determining the question of sufficient similarity, a substantial measure of discretion is accorded to the trial judge. Heifner v. Synergy Gas Corp., 883 S.W.2d 29, 35 (Mo. App. S.D. 1994). In Klein v. General Electric Co., 714 S.W.2d 896, 904 (Mo. App. E.D. 1986), it was within the discretion of the trial court to exclude a coffee maker that had been subjected to a “fire” test but under conditions not substantially similar to the conditions in question. But cf. Vaughn v. N. Am. Sys., Nos. 62513, 62561, 1993 Mo. App. LEXIS 801, at *4 (Mo. App. E.D. June 1, 1993) (allowing coffee maker fire test despite some differences due to rigorous cross-examination and exposure of dissimilarities).

In Porter, 851 S.W.2d 725, the plaintiff trucker sustained serious eye injuries when a pump hose transferring liquid sodium aluminate exploded in his face. To rebut the defendant’s contention that he would have been uninjured if he had been wearing eye protection, the plaintiff presented video experimentation of water bursts into the face of a mannequin wearing various eye and head protection, all of which were blasted away in the process. The court permitted the experimental evidence, recognizing that there will be some inherent differences when such testing is conducted and the similarities must be in those circumstances or conditions as might supposedly affect the result in question. The results and dissimilar conditions can then be examined via cross-examination, thus leaving the test for the jury to assess.

In Heifner, 883 S.W.2d 29, the court had several concerns regarding the admissibility of a courtroom demonstration and therefore did not allow it. There were many variations between the propane explosion that was the subject of the case and the proposed demonstration. Further, the plaintiff provided late notice of his intent to engage in the offered courtroom...