One common criticism of expert witness gatekeeping after the Supreme Court’s Daubert decision has been that the decision contravenes the claimed “liberal thrust” of the Federal Rules of Evidence. The criticism has been repeated so often as to become a cliché, but its frequent repetition by lawyers and law professors hardly makes it true. The criticism fails to do justice to the range of interpretations of “liberal” in the English language, the context of expert witness common law, and the language of Rule 702, both before and after the Supreme Court’s Daubert decision.
The first problem with the criticism is that the word “liberal,” or the phrase “liberal thrust,” does not appear in the Federal Rules of Evidence. The drafters of the Rules did, however, set out the underlying purpose of the federal codification of common law evidence in Rule 102, with some care:
“These rules should be construed so as to administer every proceeding fairly, eliminate unjustifiable expense and delay, and promote the development of evidence law, to the end of ascertaining the truth and securing a just determination.”
Nothing could promote ascertaining truth and achieving just determinations more than eliminating weak and invalid scientific inference in the form of expert witness opinion testimony. Barring speculative, unsubstantiated, and invalid opinion testimony before trial certainly has the tendency to eliminate full trials, with their expense and delay. And few people would claim unfairness in deleting invalid opinions from litigation. If there is any “liberal thrust” in the purpose of the Federal Rules of Evidence, it serves to advance the truth-finding function of trials.
And yet some legal commentators go so far as to claim that Daubert was wrongly decided because it offends the “liberal thrust” of federal rules.[1] Of course, it is true that the Supreme Court spoke of basic standard of relevance in the Federal Rules as being a “liberal” standard.[2] And in holding that Rule 702 did not incorporate the so-called Frye general acceptance rule,[3] the Daubert Court observed that drafting history of Rule 702 failed to mention Frye, just before invoking liberal-thrust cliché:
“rigid ‘general acceptance’ requirement would be at odds with the ‘liberal thrust’ of the Federal Rules and their ‘general approach of relaxing the traditional barriers to ‘opinion testimony’.”[4]
The court went on to cite one district court judge famously hostile to expert witness gatekeeping,[5] and to the “permissive backdrop” of the Rules, in holding that the Rules did not incorporate Frye,[6] which it characterized as an “austere” standard.[7]
While the Frye standard may have been “austere,” it was also widely criticized. It was also true that the Frye standard was largely applied to scientific devices and not to the scientific process of causal inference. The Frye case itself addressed the admissibility of a systolic blood pressure deception test, an early attempt by William Marston to design a lasso of truth. When courts distinguished the Frye cases on grounds that they involved devices, not causal inferences, they left no meaningful standard in place.
As a procedural matter, the Frye general acceptance standard made little sense in the context of causal opinions. If the opinion itself was generally accepted, then of course it would have to be admitted. Indeed, if the proponent sought judicial notice of the opinion, a trial court would likely have to admit the opinion, and then bar any contrary opinion as not generally accepted.
To be sure, before the Daubert decision, defense counsel attempted to invoke the Frye standard in challenges to the underlying methodology used by expert witnesses to draw causal inferences. There were, however, few such applications. Although not exactly how Frye operated, the Supreme Court might have imagined that the Frye standard required all expert witness opinion testimony to be based on “sufficiently established and accepted scientific methods. The actual language of the 1923 Frye case provides some ambivalent support with its twilight zone standard:
“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 the 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]
There was always an interpretative difficulty in how exactly a trial court was supposed to poll the world’s scientific community to ascertain “general acceptance.” Moreover, the rule actually before the Daubert Court, Rule 702, spoke of “knowledge.” At best, “general acceptance,” whether of methods or of conclusions, was merely a proxy, and often a very inaccurate one for an epistemic basis for disputed claims or conclusions at issue in litigation.
In cases involving causal claims before Daubert, expert witness opinions received scant attention from trial judges as long as the proffered expert witness met the very minimal standard of expertise needed to qualify to give an opinion. Furthermore, Rule 705 relieved expert witnesses of having to provide any bases for their opinions on direct examination. The upshot was that the standard for admissibility was authoritarian, not epistemic. If the proffered witness had a reasonable pretense to expertise, then the proffering party could parade him or her as an “authority,” on whose opinion the jury could choose to rely in its fact finding. Given this context, any epistemic standard would be “liberal” in freeing the jury or fact finder from the yoke of authoritarian expert witness ipse dixit.
And what exactly is the “liberal” in all this thrusting over Rule 702? Most dictionaries report that the word “liberal” traces back to the Latin liber, meaning “free.” The Latin word is thus the root of both liberty and libertine. One of the major, early uses of the adjective liberal was in the phrase “liberal arts,” meant to denote courses of study freed from authority, dogmas, and religious doctrine. The primary definition provided by the Oxford English Dictionary emphasizes this specific meaning:
“1. Originally, the distinctive epithet of those ‘arts’ or ‘sciences’ (see art 7) that were considered ‘worthy of a free man’; opposed to servile or mechanical. … . Freq. in liberal arts.”
The Frye general acceptance standard was servile in the sense of its deference to others who were the acceptors, and it was mechanical in its reducing a rule that called for “knowledge” into a formula for nose-counting among the entire field in which an expert witness was testifying. In this light, the Daubert Court’s decision is obvious.
To be sure, the OED provides other subordinate or secondary definitions for “liberal,” such 3c:
“Of construction or interpretation: Inclining to laxity or indulgence; not rigorous.”
Perhaps this definition would suggest that a liberal interpretation of Rule 702 would lead to reject the Frye standard because it was rigorous in determining admissibility on a rigid proxy determination that was not necessarily tied to the rule’s requirement of knowledge. Of course, knowledge or epistemic criteria in the Rule imply a different sort of rigor, one that is not servile or mechanical.
The epistemic criterion built into the original Rule 702, and carried forward in every amendment, accords with the secondary meanings given by the OED:
“4. a. Free from narrow prejudice; open-minded, candid.
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esp. Free from bigotry or unreasonable prejudice in favour of traditional opinions or established institutions; open to the reception of new ideas or proposals of reform.”
The Daubert case represented a step in direction of the classically liberal goal of advancing the truth-finding function of trials. The counter-revolution of let it all in, under the guise of finding challenges to expert witness opinion as going to “weight not admissibility,” or to inventing “presumptions of admissibility” should be seen for what they are: retrograde and illiberal movements in jurisprudential progress.
[1] See, e.g., Michael H. Graham, “The Expert Witness, Predicament: Determining ‘Reliable’ Under the Gatekeeping Test of Daubert, Kumho, and Proposed Amended Rule 702 of the Federal Rules of Evidence,” 54 U. Miami L. Rev. 317, 321 (2000) (“Daubert is a very incomplete case, if not a very bad decision. It did not, in any way, accomplish what it was meant to, i.e., encourage more liberal admissibility of expert witness evidence.”)
[2] Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579,587 (1993).
[3] Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).
[4] Id. at 588, citing Beech Aircraft Corp. v. Rainey, 488 U. S. 153, 169 (citing Rules 701 to 705); see also Edward J. Imwinkelried, “A Brief Defense of the Supreme Court’s Approach to the Interpretation of the Federal Rules of Evidence,” Indiana L. Rev. 267, 294 (1993)(writing of the “liberal structural design” of the Federal Rules).
[5] Jack B. Weinstein, “Rule 702 of the Federal Rules of Evidence is Sound; It Should Not Be Amended,” 138 F. R. D. 631 (1991) (“The Rules were designed to depend primarily upon lawyer-adversaries and sensible triers of fact to evaluate conflicts”).
[6] Daubert at 589.
[7] Id.
[8] Frye v. United States, 54 App. D.C. 46, 293 F. 1013 (1923).
