Tests for Legal Viability

The Frye Test

The standard test for admissibility of expert witness testimony and it accompanying lab data used by both federal and state courts from 1923 until 1993 was based on the 1923 ruling in Frye v. United States. The Frye test requires that the scientific principles upon which the work is based is "sufficiently established to have gained general acceptance in the particular field in which it belongs."

The Frye test is a conservative standard that is intended to be an obstacle for introduction of evidence based on new scientific principles or dubious scientific grounds. Using Frye, a judge must test the viability of expert testimony before allowing it in court using three points:

  1. The scientific test's reliability must be established by its general acceptance in the relevant scientific community.
  2. The testifying witness must be properly qualified.
  3. The proponents of the evidence must demonstrate that the correct scientific procedures were used.

None of these rules would pose a significant barrier for the normal environmental or geochemical tests methods, which are well documented, standardized and accepted throughout their scientific communities.

The Daubert Test

A general set of admissibility standards called the "Federal Rules of Evidence" was adopted in 1975. Federal judges were given more discretion in making admissibility determinations for all kinds of evidence:

  • Rule 104(a) assigns judges the responsibility of making a preliminary determination on whether to allow a given expert to testify.
  • Rule 702 (a.k.a. "gatekeeper" rule) requires the judge to determine if the admission of such testimony will assist in the trier of fact, i.e. understand evidence or determine a fact at issue.
  • Rule 403 suggests that the judge may exclude evidence if its likely prejudicial effect outweighs its probative value.

The conservative Frye standard was out of line with the more liberal admissibility standard contained in the new Federal Rules of Evidence. Still, it continued to survive until 1993, when US Supreme Court issued an opinion in the case of Daubert v. Merrell Dow Pharmaceuticals that abandoned the earlier Frye standard in federal cases and set a new standard.

The Supreme Court received a considerable number of briefs from scientific organizations and reflected some of those recommendations in their opinion. While the question of what constitutes reliable scientific evidence is still open for discussion, the court provided four non-definitive factors to consider in making a determination (a fifth has been added by the Seventh Circuit court.) A judge must take into account the following:

  1. whether the theory or technique can be and has been tested
  2. whether it has been subjected to peer review and publication
  3. the known or potential error
  4. the general acceptance of the theory in the scientific community
  5. whether the proffered testimony is based upon the expert’s special skill

Federal courts have taken their role as gatekeepers under Daubert very seriously and used the standard to exclude "junk science" well before the trial. Expert testimony that easily would have passed the Frye test is being excluded under the more stringent requirements of the Federal Rule of Evidence 702 as interpreted in Daubert. See also Reference Manual on Scientific Evidence.

Kumho Tire Case: Daubert is Extended

The Daubert case was about scientific evidence and did not address whether it was to be used outside the "hard" sciences. The federal courts were sharply divided over the applicability of Daubert to experts having technical or specialized knowledge (engineers) or opinions based on experience and training. The U.S. Supreme Court finally settled the issue in 1999 in Kumho Tire v. Carmichael, when the court extended Daubert to testimony provided by all experts (including engineers) in federal court.

Next: Individual States' Ruling Preferences

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