New Amendment Reiterates and Reinforces the Existing Standard for Admissibility of Expert Testimony

On December 1, 2023, the United States Supreme Court adopted the Rules Committee’s proposed Amendment to the Federal Rules of Evidence Rule 702, governing the admissibility of expert testimony.  Rule 702 is often referred to as the “Daubert” standard, because it was formed out of the Supreme Court’s landmark 1993 opinion in Daubert v. Merrell Dow Pharmaceuticals.  Critically, in the decades since the adoption of the Daubert standard and the 2000 Rule 702 amendment, courts have not uniformly applied the standard, and, in many instances, have not applied it correctly.  As a result, the Rules Committee proposed and the Supreme Court approved amendments to Rule 702 in order to reiterate the proper standard and the trial judge’s fundamental role as gatekeeper.

Rule 702 now reads:

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that:

(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and methods; and

(d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.

While the Amendment did not change the standard for admissibility of expert testimony, it makes clear what the standard has been since Daubert and the 2000 Amendment to Rule 702. 

Daubert and Two Previous Amendments to Rule 702

In Daubert v. Merrell Dow Pharmaceuticals, Inc., the Supreme Court held that the Frye standard for determining admissibility of expert testimony was displaced by the Federal Rules of Evidence.  The Frye standard, also called the “general acceptance” test, predicated the admissibility of expert testimony on whether the testimony was deduced from a “well-recognized scientific principle or discovery” and required that the method of deduction must be sufficiently established, as to have “gained general acceptance in the particular field in which it belongs.”   Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993); Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). 

The Supreme Court in Daubert pointed out that the Federal Rules of Evidence never mention a “general acceptance” standard, nor is there any mention of Frye whatsoever in the drafting history.  Thus, the Rules did not assimilate Frye and that standard should not be applied in federal court.  Rather, federal courts should apply Rule 702, which describes a different standard for regulating the admission of expert testimony.

As viewed by the Supreme Court, Rule 702’s “overarching subject” is the scientific validity of the principles that underlie proposed testimony (quoting Daubert v. Merrell Dow Pharmaceuticals, Inc.).  The testimony must be relevant and reliable, and courts should make this determination based on the principles and methodology the expert uses, not on the conclusions the expert reaches. 

In Daubert, the Supreme Court also addressed the concerns of amici who feared that judges possessing the power to “screen” testimony would be “stifling and repressive” to a jury’s search for truth.  However, the Court found that it was necessary under Rule 702 for the courts to take on a “gatekeeping role.”  Despite the fact that this gatekeeping may at times exclude new insights and innovations from a jury, the Court found it more valuable and judicially efficient for courts to have the power to exclude “conjectures that are probably wrong” in order to reach “quick, final, and binding legal judgment[s].”  The Supreme Court made clear in Daubert that the value of Rule 702 lies in the gatekeeping function, which ensures judicial efficiency and sound legal judgment by allowing courts to exclude testimony which is not based on scientifically reliable methods. 

2000 Amendment to Rule 702 Requires Trial Judges to Exclude Unreliable Testimony

To ensure uniform application of the standard set out in Daubert, the Supreme Court amended Rule 702 in 2000.  In its Comments to the 2000 Amendment, the Rules Committee made clear that the Daubert standard, as clarified by Kumho Tire Co. v. Carmichael,required trial judges to act as gatekeepers to exclude unreliable expert testimony, and that this gatekeeping role was required under Rule 702.  The Committee’s Comments on the Amendment further expounded that the proponent has the burden of proving admissibility requirements by a preponderance of the evidence.  Overall, the amendment made clear that the standard laid out by Daubert was being formally adopted, and that the Daubert case provided the legal foundations for the 2000 Amendment. 

2011 Amendment to Rule 702 Addresses Admissibility

The Supreme Court again amended Rule 702 in 2011.  The Rules Committee’s Comments explain that the amendments were made to emphasize that the proponent of expert testimony must demonstrate to the court by a preponderance of the evidence that the testimony meets the admissibility requirements.  The Committee concluded that the preponderance of the evidence standard was made necessary by the “many courts [which] have held that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility.”  The Committee outright stated that “[t]hese rulings are an incorrect application of Rules 702 and 104(a).”  The Supreme Court adopted the 2011 Amendment, emphasizing the importance of reliability and the court’s role as gatekeeper.  Yet, despite these amendments, courts continue to misapply the Rule 702/Daubert standard. 

Federal Courts Have Not Consistently Applied Rule 702/Daubert Uniformly or Correctly

Despite the standard established in Daubert, and Rule 702’s specific call upon courts to carry out their gatekeeper function, many federal courts have effectively abdicated their gatekeeping role by failing to apply Rule 702/Daubert uniformly or correctly.  In particular, and as pointed out by the Rules Committee in its notes to the 2023 Amendment, some federal courts held that arguments regarding the sufficiency of an expert’s basis for an opinion always go to weight and not admissibility. 

Examples of improper application include Liquid Dynamics Corp. v. Vaughan Co., Inc. where the United States Court of Appeals Federal Circuit refused to exclude an expert’s testimony after analyzing an argument challenging the parameters an expert applied in conducting computational fluid dynamics analysis in a computer simulation.  The Court explained that the challenge, based on the fact that the expert’s computational analysis used incorrect data and the wrong equation, indicated that the evidence was unreliable.  However, the Court held, this attack went to weight rather than admissibility. 

But the sufficiency element is not the only shortcoming of federal courts applying Rule 702/Daubert.  In fact, the Committee found Courts have been consistently misapplying regarding the “pertinent considerations” laid out by Justice Blackmun’s Daubert opinion.  The pertinent considerations are: (1) whether the method has been tested, (2) whether the method has been subjected to peer review, (3) potential rate of error, (4) existence of standards controlling the method’s operation, and (5) the degree of acceptance within the (relevant) scientific community. 

Though courts cite these factors in their Rule 702 analyses, they have failed to properly apply the factors to carry out their gatekeeping function.  For example, the Third, Fourth, Seventh, and Ninth Circuits have held that “peer review” does not require actual peer review by a number of experts prior to publication—rather, peer review simply means that a second person has reviewed the methodology. 

Similarly in addressing the “potential rate of error” factor, the First Circuit in United States v. Mahone accepted the claim that a study had “a potential error rate of zero for the method [because] any error is attributable to examiners.” 

In United States v. Baines, the Tenth Circuit found that the known error rate in fingerprint analysis was impressively low  because the state fingerprint expert could not name any mistakes he himself had made and the FBI fingerprint expert stated that he did not know of many mistakes in fingerprint casework. 

These flawed applications of Rule 702/the Daubert standard by federal courts resulted in the improper admission of unreliable expert testimony under the guise of applying Daubert. 

New Amendment Provides Clarification and Course Correction

Unlike other amendments to the Rules, the 2023 amendment to Rule 702 does not change the applicable standard or create any new procedure.  Instead, as explained by the Advisory Committee, the amendment was intended to clarify the rule and correct the misunderstandings being perpetuated by courts regarding its application.  In other words, the amendment did not work a “sea change” over the Rule 702 standard, but rather just clarified and restated what the standard has always been since Daubert/the 2000 Amendment.

First, the amendment clarifies that expert testimony cannot be admitted unless the proponent satisfies the preponderance of the evidence standard.  This clarification addresses the failure by courts to correctly apply the reliability-based admissibility requirements.  It is directed to particularly those courts which have held that arguments about the sufficiency of an expert’s basis for an opinion always go to the weight of the testimony and not admissibility. 

Second, the clarifications also reiterate the critical role of judicial gatekeeping.  The Advisory Committee explained that “jurors may be unable, due to lack of specialized knowledge, to evaluate meaningfully the reliability of scientific and other methods underlying expert opinion[.]”  Further, “jurors may also lack the specialized knowledge to determine whether the conclusions of an expert go beyond what the expert’s basis and methodology may reliably support.”  Thus, the role of the court is critical to ensure that only reliable expert opinions are considered by the jury. 

As the Advisory Committee pointed out in its Notes “nothing in the [Rule 702] amendment imposes any new, specific procedures.”  The amendment is a clarification, rather than a substantive change, indicating that it need not be “adopted” per se, but merely followed by the courts applying the Daubert standard.  These clarifications are merely restatements to make clear to courts what the law has always been: that courts are the gatekeepers of expert testimony and that expert testimony must be based on reliable principles and methods. 

As the Fourth Circuit in Sardis v. Overhead Door Corp. affirmed in discussing Rule 702, “the importance of [the] gatekeeping function cannot be overstated.”  The Fourth Circuit in Sardis went on to discuss the pending (at that time) amendments to Rule 702.  The Court stated that the now-accepted Rule 702 amendments are consistent with the existing law explaining a court’s gatekeeping function and merely confirm the nature of the gatekeeping function in cases where expert testimony is challenged. 

Rule 702/Daubert is Not Limited to Federal Courts

Since the 2000 amendment to Rule 702, 32 out of 50 states follow at least some version of the Daubert standard.  Although some of these states have expounded upon it or combined it with their own common law standard, each of the states that has adopted the Daubert standard employs its basic foundational premise: scientific expert testimony must be the product of reliable methods.

Because the 2023 Amendment does not change the Daubert standard, the Committee notes to the Amendment and the post-amendment cases applying Rule 702 should provide additional support for ensuring the admission of only reliable expert testimony in the states which have adopted the Daubert standard, even if they have not specifically adopted the amendment. The Amendment and additional case law should be applicable and persuasive in those states which have adopted Rule 702 (2000) and Daubert, but whose courts have “gone astray” by failing to properly apply the standard.