Section 13.31 Expert Witnesses and Computer-Generated Evidence

• Library: Sources of Proof (2014 Ed.)

Experts often rely on software programs to perform calculations that then become the subject of testimony. Reliance on software may raise a variety of issues, including the:

• accuracy of results of the software;

• accuracy of the underlying data; and

• competency of the expert to endorse the conclusions of the software.

Guidelines for the use of software were laid down in Bray v. Bi-State Development Corp., 949 S.W.2d 93 (Mo. App. E.D. 1997).

In Bray, 949 S.W.2d 93, the relevant issue was the level of light at the time the plaintiff fell in a parking garage. To determine this level, counsel for the defendant called an expert who used a software program. The program accepted variables such as the height, spacing, wattage, and type of artificial light in the garage, and the software program output the light level on a horizontal surface. The expert further captured factors representing the age of the bulb and the presence of dirt. Finally, he measured actual light to generally check the results. The plaintiff objected on the basis that there was no adequate foundation for the software. Id. at 96. Noting that Missouri courts had not addressed the issue, the court looked to the three guidelines set forth in Commercial Union Insurance Co. v. Boston Edison Co., 591 N.E.2d 165 (Mass. 1992):

“(1) The computer is functioning properly;

(2) The input and underlying equations are sufficiently complete

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