In the wake of Kumho Tire Co. Ltd. v. Carmichael,1 more forensic experts than ever in scientific and technical fields are testing the theories about which they testify in major litigation. The admissibility of testing or "experimental" evidence is often crucial. The stakes are high. The cost of conducting proper testing can be considerable, but the cost of losing the case if a party fails to test (or if the court excludes the test) is enormous. In large measure, the jury's verdict may rest on demonstrative evidence offered to persuade jurors by helping them understand the testing performed by the experts and its significance to the issues in dispute. If the court excludes the testing evidence in whole or in part, the proponent's case may be doomed. The stakes are equally great for the opponent of such evidence. If the stakes are higher than ever, so is the frequency with which the admissibility of evidence of testing is the decisive issue in the case. This is partly because of the effect of Kumho, but it is also due to the increasing sophistication of forensic testing and demonstrative evidence.

Although many of the leading cases arise in automotive product liability cases, the issue transcends that area of civil litigation and encompasses a broad range of cases. Given its importance, one might expect that the rules of evidence would provide clear criteria governing the admissibility of experimental and demonstrative evidence. Unfortunately, this is not the case. The U.S. Court of Appeals for the Fifth Circuit's decision in Muth v. Ford Motor Co.2 illustrates persistent problems with federal courts' treatment of experimental evidence. As a result of the Kumho decision and the subsequent revisions to Rule 702 of the Federal Rules of Evidence (hereinafter "Federal Rules"), 3 experts typically are required to test their hypotheses if possible, to conduct the test in accordance with the rigors of their profession, and to apply the results reliably to the facts. But, if evidence of tests satisfying those requirements is offered at trial, courts continue to rule unpredictably on the admissibility of those tests.