American Scientist

Expert witnesses are common in the courtroom. They testify in approximately 80 percent of all civil cases and 50 percent of all felony cases, and often they are scientists and engineers. This presents unique problems for the legal profession. Mostly untrained in science and engineering, lawyers must present this testimony coherently and judges must determine whether it should be excluded or admitted. What criteria judges use to determine admissibility has itself been the object of much legal debate and opinion over the years, and it came to a head most recently with three landmark cases decided by the Supreme Court of the United States. In 1993 the court's ruling in the case of Daubert v. Merrell Dow Pharmaceuticals established "the standard for admitting expert scientific testimony in a federal court." In 1997 the court provided further guidance in General Electric v. Joiner, and just this spring, in Kumho Tire v. Carmichael, it addressed the question of whether there is a distinction between scientific and engineering knowledge as far as the courts are concerned. The full import of these decisions, especially that of Daubert and Kumho, can best be understood in the historical context of judicial rules governing expert testimony.