Daubert “Fit” and the “Appropriateness” of Expert Testimony Under Rule 5-702(2)
With Maryland’s formal adoption of the Daubert standard for admissibility of expert testimony in all civil and criminal cases, the meaning of Maryland Rule 5-702 should now mirror the meaning of Federal Rule of Evidence 702. But the textual structure and ordering of the two rules still differs. The federal rule was revised in 2000 to better reflect the holdings of the Daubert trilogy. The Maryland rule was modeled after FRE 702 as it existed in 1995.
Despite their different structure and ordering, the two rules, which are presented in full at the bottom of this post, share three core requirements for expert testimony:
- Qualifications: both rules require that the witness be “qualified as an expert by knowledge, skill, experience, training, or education.”
- Helpfulness: Both rules require that the testimony will either “help” (FRE 702(a)) or “assist” (Md. R. 5-702) “the trier of fact to understand the evidence or to determine a fact in issue.”
- Sufficient Factual Basis: The rules require that the testimony rest upon either “a sufficient factual basis” (Md. R. 5-702(3)) or “sufficient facts or data” (FRE 702(b)). Incorporating the Daubert trilogy, the federal rule then spells out that the testimony must be “the product of reliable principles and methods” (FRE 702(c)) that were “reliably applied” to “the facts of the case.” (FRE 702(d)). Maryland has long imposed the same requirement through case law. See Rochkind v. Stevenson, 471 Md. 1, 22 (2020).
This covers six of the seven subsections of the aggregated federal and state rules. But it does not cover Md. Rule 5-702(2). Subsection (2) requires the trial judge to determine “the appropriateness of the expert testimony on the particular subject.” But what does that even mean? Taken literally, it could apply to any part of Rule 702 or 5-702. For example, testimony is not “appropriate” from an expert who is not qualified on the particular subject. Nor is testimony “appropriate” if it lacks a sufficient factual basis, even from a well-qualified expert. But the appropriateness requirement is not mere surplusage.
The “appropriateness” provision seems most relevant to the broadly worded requirement that expert testimony “help” or “assist the trier of fact to understand the evidence or to determine a fact in issue.” By itself, the disjunctive requirement could open the door to almost limitless testimony. Almost any expert’s testimony can “assist the trier of fact to understand the evidence.” But trials are not free-for-alls where parties can line up experts to opine on any complex matters in the case. Expert testimony should also help the jury “determine a fact in issue.” Admissible expert testimony should “assist the trier of fact to understand the evidence” and “to determine a fact in issue.”
So the Daubert Court and countless other courts have boiled down the overlapping concepts of helpfulness, relevance, and appropriateness into one simple word: “fit.” Expert testimony fits the case if “it will aid the jury in resolving a factual dispute” in the case. 509 U.S. at 591 (quoting United States v. Downing, 753 F.2d 1224, 1242 (3d Cir. 1985) (Becker, J.). Fit brings a crucial element of materiality to the admissibility analysis. Expert testimony that is not tied to resolving the material disputes in the case is not merely inefficient. If not truly relevant to a disputed issue, it would presumably be offered only to mislead the jury from the relevant inquiry for the benefit of the proponent. That is why the Daubert decision emphasized that “Rule 702’s ‘helpfulness’ standard requires a valid scientific connection to the pertinent inquiry as a precondition to admissibility.” Id. at 591-92.
Applying Daubert, Judge Becker’s home circuit instructs “that Rule 702 embodies a trilogy of restrictions on expert testimony: qualification, reliability and fit.” Schneider v. Fried, 320 F.3d 396, 404 (3d Cir. 2003). To “fit,” the “expert’s testimony must be relevant for the purposes of the case and must assist the trier of fact.” Id. That is the analysis that Maryland courts and practitioners should apply when considering the “appropriateness” of expert testimony under Rule 5-702(2).
Full Text of Rules:
Md. Rule 5-702. Testimony by Experts
Expert testimony may be admitted, in the form of an opinion or otherwise, if the court determines that the testimony will assist the trier of fact to understand the evidence or to determine a fact in issue. In making that determination, the court shall determine
(1) whether the witness is qualified as an expert by knowledge, skill, experience, training, or education,
(2) the appropriateness of the expert testimony on the particular subject, and
(3) whether a sufficient factual basis exists to support the expert testimony.
Fed. Rule 702. Testimony by Expert Witnesses
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:
(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 has reliably applied the principles and methods to the facts of the case.