Thomas L. Bohan


In 1993, the Supreme Court of the United States stated that with the federal adoption of statutory rules of evidence in 1975, the common law rule for determining admissibility of scientific testimony was superseded, and that thenceforth admissibility of scientific testimony was to be determined solely by Federal Rule of Evidence 702 (Rule 702). The Frye standard had been adopted in one form or another by most of the federal circuits and by many of the state courts during the 70 years preceding Daubert. Referred to as the “general acceptance” standard, the Frye standard--although adopted in a variety of forms--had the core requirement that proffered scientific testimony be based on something enjoying “general acceptance” among some set of scientists. It was an effort to ensure that expert testimony had some measure of reliability. The Daubert Court, in agreement with Petitioners and with the authors of six of the twenty-two amicus briefs that had been filed, held that the strictness of the Frye “general acceptance” requirement was not in keeping with the goal of the Federal Rules of Evidence to liberalize admission criteria. If the Court had stopped there, Daubert would be tantamount to the Maine scientific evidence rule, as set out in State v. Williams. But it did not stop there. Instead, engaging in what some might characterize as an exegesis, the Court asserted that since inaccurate expert testimony could not “determine a fact in issue,” it was necessary for the trial judge to exclude expert testimony not based on the scientific method. The Court thereby brought in through the back door the same reliability concern that had led to the widespread adoption of Frye in the first place. This author asserts that, contrary to popular legal and lay belief, the significance of Daubert lies not in its discarding of Frye and its emphasis on Rule 702, but rather in its exhorting of trial judges to exercise their “gatekeeper” role with respect to scientific evidence, something that many had been fairly lax about previously. It is precisely because trial judges have taken this gatekeeper role more seriously than in the past that a revolution is occurring in scientific evidence and forensic science. Adding to the pressure for reexamination and change has been the plethora of DNA-based wrongful-conviction discoveries of the past decade. Men convicted of the most heinous crimes, and often sentenced to death, have subsequently been found indisputably innocent of those crimes. Just as an autopsy provides a post-mortem check of a physician's cause-of-death finding and/or an earlier diagnosis of disease, the post-conviction DNA analysis can provide a check on the correctness of a verdict or plea. Of course, there is less symmetry in the legal selection process than there is in the medical. Although autopsies are generally sought whenever there is uncertainty in the diagnosis or cause of death, post-conviction DNA reviews are sought only to prove that the guilty verdict was mistaken, that it represented a “false positive.” No one seeks such reviews to support a verdict of innocence. Furthermore, it is unlikely that a prosecutor would ever seek such a review to support a verdict (or plea) of guilty. Once the wrongful-conviction findings began to surface, there was great interest in investigating what had gone wrong at the underlying trials. It was realized that, in addition to answering the pressing specific question, the results of such an investigation might have significance for criminal trials in general, regardless of the crime charged, and for civil trials. Presumably, errors that were occurring in trials that could be checked with DNA analysis were also occurring in trials for which DNA analysis was not available. The most common threads running through the trials that led to wrongful convictions are a paucity of evidence and the failure of the defense to put on a forensic expert. In many of the cases, there was no physical evidence at all and the prosecution's case rested entirely on eye witness testimony, sometimes from a single witness. The forensic science community was most dismayed by those cases where the wrongful verdict was based on specious forensic testimony. In most instances, the testimony involved exaggerating, either through implication or direct lying, the significance of those tests that had been done. A typical example would involve the claim that hairs can be “individualized” by microscopic examination, leading to the conclusion that specimens of the defendant's hair had been found at the crime scene. Although the falsity of such statements has long been recognized in professional scientific literature, it seems not to be recognized by the majority of the public. This means that, in the absence of effective opposition, a jury will probably accept the false testimony at face value and as persuasive evidence. Even if the witness only makes a literally true statement that the hair specimen found at the scene “is consistent with” being the defendant's, a jury and judge not familiar with this type of evidence, and not alert to the “is consistent with” subterfuge, can be influenced to the severe detriment of the defendant. A knowledgeable defense expert can help cure such testimony or even prevent it from being offered in the first place.

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