Academic journal article Harvard Law Review

Admitting Doubt: A New Standard for Scientific Evidence

Academic journal article Harvard Law Review

Admitting Doubt: A New Standard for Scientific Evidence

Article excerpt

Since Daubert v. Merrell Dow Pharmaceuticals, Inc., (1) federal judges have had the responsibility to act as gatekeepers of scientific expert testimony (2) through a two-pronged test to determine whether "an expert's testimony both rests on a reliable foundation and is relevant to the task at hand," (3) based not on the expert's conclusions but on the "principles and methodology" (4) used. Most state courts now use either the Daubert test, the older test from Frye v. United States (5) requiring general acceptance by the relevant scientific community, or a mixture of the two standards. (6)

However, both tests mistakenly import scientific standards into the fundamentally legal decision of admissibility. This Note argues that admissibility should be based on relevance, with no separate reliability assessment, and also that judges should instruct juries on various factors related to reliability. This approach will improve accuracy by better informing the jury and by admitting evidence that does not meet current standards but that should be used to answer questions of fact. It also serves non-accuracy values by making adjudication fairer and by avoiding the inappropriate importation of scientific norms into law. The Note first describes relevant legal precedents and philosophy of science principles. It then discusses the different treatment of evidence in law and science and argues that current standards fall short of fulfilling the purposes of legal evidence. Finally, the Note sets out the proposed standard and explains why it provides a better solution.


A. Current Standards

From 1923 to 1993, the Frye "'general acceptance' test [was] the dominant standard for determining the admissibility of novel scientific evidence." (7) The test draws the line for admissibility based on whether the scientific principle underlying the evidence is accepted by a sufficient portion of the relevant scientific community:

   Just when a scientific principle or discovery crosses the line
   between the experimental and demonstrable stages is difficult to
   define. Somewhere in this twilight zone the evidential force of the
   principle must be recognized, and while courts will go a long way in
   admitting expert testimony deduced from a well-recognized scientific
   principle or discovery, the thing from which the deduction is made
   must be sufficiently established to have gained general acceptance in
   the particular field in which it belongs. (8)

Thus, Frye requires the judge to determine the relevant scientific field and then to determine whether the members of that field have widely accepted the idea at issue. Prior to Frye, judges generally based admissibility upon an assessment of the expert rather than the testimony: experts needed to be qualified, and qualification was often based on whether an expert had success in the commercial marketplace. (9)

In Daubert, the Supreme Court held that the general acceptance doctrine was superseded by Rule 702 of the Federal Rules of Evidence: "If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise." (10) The Court also noted that Rule 702 applied to all scientific evidence rather than only to the novel evidence specified by the Frye opinion. (11) Elaborating on the specific inquiries required by the statute, the Court set out a two-part analysis:

   Faced with a proffer of expert scientific testimony, then, the trial
   judge must determine at the outset ... whether the expert is
   proposing to testify to (1) scientific knowledge that (2) will assist
   the trier of fact to understand or determine a fact in issue. This
   entails a preliminary assessment of whether the reasoning or
   methodology underlying the testimony is scientifically valid and of
   whether that reasoning or methodology properly can be applied to the
   facts in issue. … 
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