Expert testimony frequently plays a dispositive role in mass tort and complex product liability cases, and the applicable standard used to determine whether such key evidence is admissible in state court can vary across state lines. The two principal standards of admissibility, Daubert and Frye, have been the subject of innumerable commentaries and articles, with some debating the relative pros and cons, including which standard is stricter;1 others advocating for particular states to either keep or modify Frye or adopt Daubert;2 and still others hypothesizing, as did at least one article previously featured in this publication, that the difference between Daubert and Frye does indeed make a difference in practice. While providing background on both standards, this article focuses on the primary differences between the two and presents the prevalent views on whether which standard a state applies really makes any difference in the way scientific evidence is handled in practice.
Background: Frye and Daubert
In 1923, the “general acceptance” standard for the admissibility of scientific evidence was set in Frye v. United States. Frye involved a murder trial where the defendant unsuccessfully sought to introduce expert testimony regarding a lie detector test based on changes in systolic blood pressure. In upholding the exclusion of such evidence, the D.C. Circuit noted that the test had not gained “standing and scientific recognition among physiological and psychological authorities” and thus had not gained “general acceptance in the particular field in which it belongs.”3
Frye was not often cited until years later—and not regularly until the 1970s—and even then it was applied primarily in criminal cases.4 It was not applied in a federal civil case until 1984.5 But as more federal courts and most state courts adopted or applied Frye, confusion arose about whether Frye was superseded by the enactment of the Federal Rules of Evidence in 1975. Absent from the text of then Rule 702, of course, was any reference to “general acceptance.”
The Supreme Court addressed this very issue in 1993 when it decided Daubert v. Merrell Dow Pharmaceuticals.6 In Daubert, the Court determined that trial judges must not only ascertain the “general acceptance” of expert testimony, but also ensure that such testimony is “relevant to the task at hand” and “rests on a reliable foundation.” 7 The Court further enumerated four nonbinding factors courts could consider in evaluating the admissibility of expert testimony: (1) whether such evidence was generally accepted by the relevant scientific community; (2) whether the methodology was published and subject to peer review; (3) whether the methodology has a known or potential rate of error; and (4) whether the results are testable.8 Daubert was further refined by Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137 (1999) (extending Daubert’s general holding to include nonscientific, or technical, expert testimony), and General Electric Co. v. Joiner, 522 U.S. 136 (1997) (finding that determinations regarding admissibility of expert testimony were to be reviewed for abuse of discretion). These three cases, referred to as the “Daubert trilogy,” are the law in federal court.
Today, the majority of states have adopted Daubert, if not in name, then in ways that are nearly identical doctrinally. However, within these so-called Daubert states, there is some variation. Some states have adopted the entire “trilogy,” while some have adopted only certain elements of the “trilogy.” And still others, like New Jersey, have adopted Daubert, but only in certain types of cases or circumstances. A close look at the Frye states shows similar nonuniformity. Kansas, for example, will apply Frye, but only to new or developing science;9 Illinois does not apply Frye to expert medical testimony. 10 In addition to Kansas and Illinois, at least 10 other jurisdictions have retained Frye (in one form or another).11
The Principal Distinctions Between Frye and Daubert
Beyond the fact that each represents a distinct standard of admissibility, there are two principal distinctions between jurisdictions that apply Frye and those that apply Daubert— the first concerns which body (the judiciary or the scientific community) makes the call on the science, and the second concerns the evidence to which these standards apply. As to the first, under Frye, trial judges are ostensibly charged with assessing whether such testimony is “generally accepted” in the relevant scientific community. In Daubert jurisdictions, on the other hand, trial judges in their “gatekeeper” role must assess the reliability of any expert evidence.12
As to the second, in those jurisdictions that follow Kumho (or some variation thereof), Daubert extends to all types of expert testimony, whereas in many Frye jurisdictions, challenges to expert testimony are typically limited to scientific testimony only, excluding other types of expert testimony, such as expert medical testimony.13 Like the states noted above, California also significantly restricts the application of its version of Frye—so much so that “there are no reported California cases applying [Frye] to cancer causation and the like.”14
Does Frye or Daubert Make Any Difference in State Court? Three Views
The distinctions between Daubert and Frye logically suggest that the adoption of one or the other should make some difference in practice. Recently, however, some commentators have suggested that whether a state applies Daubert or Frye makes no real difference in how those courts assess the admissibility of expert testimony. One of the leading treatises on scientific evidence, for instance, articulates this notion in the following way: “[R]elatively few toxic tort case admissibility rulings actually turn on the difference between Daubert and Frye. Daubert’s shadow now casts itself over state court opinions even in jurisdictions that have not formally adopted the Daubert test.” 15 Likewise, some recent studies support the proposition that whether a state adopts Daubert or Frye makes no difference in tort cases. Of course, these are not the only views on this subject, but thoughts about what, if any, difference a state’s choice of Daubert or Frye makes can largely be grouped into the three categories that follow.
Daubert Is More Liberal Than Frye. Initially, after Daubert was decided, many commentators focused on whether it was a more lenient or liberal standard—one, in particular, that would make it more difficult to challenge expert testimony. Even the Court in Daubert noted that it was imposing a more liberal standard than Frye. In fact, the Court stated that Frye was “at odds with the ‘liberal thrust’ of the Federal Rules and their ‘general approach of relaxing the traditional barriers to “opinion testimony.” ’ ” 16 Soon after Daubert—as opposed to more recent scholarship—some even speculated that Daubert was pro-plaintiff17 and would ultimately make it easier for plaintiffs to admit expert testimony and therefore avoid potentially dispositive motions practice.18
Daubert Is Stricter Than Frye. In stark contrast to early reports that Daubert could be more liberal than Frye, one survey of post-Daubert product liability decisions revealed that two-thirds excluded expert testimony.19 Other data showed that parties—and especially civil defendants—were hardly shy about filing Daubert motions. In the six years post-Daubert, the number of federal-court orders issuing rulings in civil cases that addressed the admissibility of expert testimony was 36 times greater than in the previous six-year period,20 and these motions were successful nearly 70 percent of the time.21
Recently, plaintiffs’ advocacy groups, apparently accepting the notion that Daubert is anything but a more liberal standard and is, instead, far stricter than Frye, have advocated against the adoption of Daubert in state courts. Scholarship, too, has referred to Daubert as “intolerable” for plaintiffs: “Plaintiffs have, in large part, been stymied by their inability to establish that toxic agents, no matter how potentially dangerous, were actually responsible for the harms they have suffered. Their difficulties in this regard have increased exponentially since the Supreme Court’s decision in Daubert v. Merrell Dow Pharmaceuticals, Inc.”22
The Standard of Admissibility Does Not Matter. Although the adoption of Daubert or Frye is viewed by many as having some impact on the outcome of admissibility determinations, other commentators increasingly question the assumption that the application of one standard over the other may have practical significance. Some suggest that the primary benefit of Daubert was not that it was a stricter standard or created a higher hurdle to admissibility, but that it heightened trial courts’ awareness of the problem of admitting unreliable science—and thus, whether a Daubert or Frye jurisdiction, the results are often the same.23 One survey found that state-court judges considered the “general acceptance” prong to be the most useful of the Daubert factors and that, while Daubert may have increased judicial scrutiny of the admissibility of expert testimony, these courts were generally applying the same analysis regardless of what standard actually applied in the respective jurisdictions.24 Other studies have yielded similar results. In one, which involved analyzing hundreds of federal and state criminal appellate decisions, researchers found that Daubert—whether in federal or state court—had no statistically significant effect on the rates of admissibility of expert testimony.25 While this latter study looked only at criminal cases, thereby making it difficult to extrapolate to the civil context, its findings nonetheless contribute to the growing suspicion that the standard of admissibility a state adopts does not matter from a practical standpoint.
Expert testimony can ignite or snuff out a mass tort or complex product liability case. And while the commentaries and articles examining the relative merits of the standards of admissibility for such evidence—Daubert and Frye—are legion, there are varying views on whether the application of one standard over another really makes any difference in practice. For litigants, this means one should not lose hope if stuck in a Frye jurisdiction. And, regardless of jurisdiction, both Daubert and Frye, if rigorously applied, have the potential to be powerful tools in limiting or excluding an opponent’s experts.