Standards of evidentiary reliability
Rule of Evidence 702, and its variations adopted by most states, defines the
admissibility of expert testimony in the following manner:
Since 1923, Frye v. US has served as the standard for determining whether an expert's testimony would "assist the trier of fact." Frye required that expert testimony be supported by scientific principles or evidence generally accepted by the relevant scientific or professional community. Frye rulings traditionally relied on peer review, particularly the availability of peer-reviewed articles, to assess general acceptance.
In 1993, the US Supreme Court's decision in Daubert v. Merrell Dow Pharmaceuticals, Inc. superseded Frye in federal courts. Daubert defines a four-prong test for determining the "evidentiary reliability" of a scientific theory or technique:
More recently, the US Supreme Court's 1999 decision in Kumho Tire, Inc. v. Carmichael further expanded the reach of Daubert. In his majority opinion, Justice Breyer wrote that a trial judge must determine whether proposed expert testimony that "reflects scientific, technical or other specialized knowledge" has a "reliable basis in the knowledge and experience of [the relevant] discipline" (Wierner, 1999, p. 47)
Whereas various courts previously ruled that Daubert was applicable only to the procedures of a laboratory science, and therefore not applicable to clinical opinion, Kumho extends Daubert to opinion testimony.
State courts are not obligated to adopt how federal courts interpret rules of evidence. Consequently, there is considerable variation between states regarding criteria for defining the admissibility of expert testimony. During the first two years after the Daubert ruling, 11 states adopted it, and five rejected it (melton et al., 1997). Assessing the evidentiary reliability of the instruments used for sexual
evaluations therefore necessitates considering both Frye and Daubert (as
further defined by Kumho).
Pursuant to Frye, any assessment instrument that has not gained general acceptance, typically via peer review, would be considered an experimental instrument. General acceptance -- as opposed to status as an experimental instrument -- also necessitates that a procedure satisfy relevant practice and ethical standards.
Frye criteria would prohibit an expert from relying on an experimental instrument while testifying in a legal proceeding. In addition to peer review and related considerations of general acceptance, Daubert would reject any assessment instrument
instruments that fail to satisfy these Daubert criteria can also be
considered as remaining at an experimental stage of development.
Rogers, Salekin, and Sewell (1999) have indicated that many commonly used
psychological tests may not satisfy standards of evidentiary reliability in
clearly, there is no acceptable rationale for exempting risk assessment
procedures from the issues raised by Rogers et al. (1999). Indeed, there
is a compelling need for systematically reviewing the instruments currently used
for risk assessment in cases of previously convicted sexual offenders.