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Law 101: Legal Guide for the Forensic Expert

Daubert and Kumho Decisions

The standard that changed the admissibility criteria set forth in Frye was the 1993 decision in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579; 113 S. Ct. 2786 (1993). In this landmark decision, the U.S. Supreme Court established a new standard by determining that the Federal Rules of Evidence assign the trial judge the role of gatekeeper, which allows the judge broad discretion in determining the admissibility of all scientific evidence into the courtroom.

The judge, as gatekeeper, may rule to admit expert testimony that rests on a reliable foundation and is relevant to the inquiry at hand by considering such factors as whether:

  • The subject of testimony is falsifiable or testable.
  • The testimony is derived from techniques with known error rates.
  • The testimony has been subjected to peer review, and whether the testimony is generally accepted in the relevant scientific community.

In addition to relevance and reliability, the decision in Daubert also established general factors based on the Federal Rules of Evidence and is meant to assist the judge. Pertinent evidence based on scientifically valid principles will usually satisfy those factors. "Guestimates" and speculation will not.

The current trend in federal courtrooms, based on the U.S. Supreme Court decision Kumho Tire v. Carmichael, is to allow expert opinion when the trial judge finds that the testimony is relevant and reliable, is based on principles set forth in Daubert, or meets any other set of reasonably reliable criteria. The rules in some state courts may differ.

For more on Daubert and Kumho Tire and their importance to testifying experts, see Module 3: Importance of Case Preparation, Topic 3: Preparation: Qualities of an Effective Expert.

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