Understanding the Rule 702 Amendments

On December 1, 2023, amendments to Federal Rule of Evidence 702, governing admissibility of expert opinion evidence, took formal effect. The amended Rule 702 makes clear that a party offering expert opinions must demonstrate that it is more likely than not that all four subparts (a)–(d) are met, and revises subpart (d) to indicate that the opinion must reflect “a reliable application of the principles and methods to the facts of the case.”

On the surface, these amendments may appear modest. But there is more here than initially meets the eye. To understand and effectively marshal the amendments, litigants must look to the history of the amendments. As the 2023 Committee Note explains, a major reason for the amendment is to

[E]mphasize that expert testimony may not be admitted unless the proponent demonstrates to the court that it is more likely than not that the proffered testimony meets the admissibility requirements set forth in the rule. . . [M]any courts 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. These rulings are an incorrect application of Rules 702 and 104(a).

Critically, these comments flatly reject the idea that the underlying bases and methodology for an expert’s opinion go to the weight, not the admissibility, of an expert’s opinion.

Though the Committee Note is clear, courts have not automatically implemented changes to established precedent as a result. Take Rodriguez v. Hospital San Cristobal, Inc., 91 F.4th 59 (1st Cir. 2024). There, the First Circuit acknowledged Rule 702’s amendment but ignored the Committee Note, reasoning that “[w]hen the factual underpinning of an expert’s opinions is weak, it is a matter affecting the weight and credibility of the testimony” and was “a question to be resolved by the jury.” This runs contrary to the express language of the Committee Note.

Other decisions highlight a lack of consistency among the courts in applying the new language. See e.g. State Auto. Mutual Insurance Co. v. Freehold Mgmt., Inc., 2023 WL 8606773 (N.D. Tex. 2023) (discussing changes to Rule 702 and ultimately excluding expert under Rule 702 “particularly [] in light of the 2023 amendments”); In re Acetaminophen, __ F. Supp. 3d __, 2023 WL 8711617 (S.D.N.Y. Dec. 18, 2023) (excluding plaintiffs’ experts opinions under amended Rule 702); U.S. v. DynCorp Int’l LLC, __ F. Supp. 3d __, 2024 WL 604923 (D.D.C. Jan. 25, 2024) (acknowledging amendments, but quoting advisory committee notes from 2000 amendments in allowing expert testimony).

To combat the risk of courts recycling pre-amendment statements of law, consider these tips when briefing motions to exclude or limit opposing experts:

• Note what is new. Remind the court that Rule 702 has been amended. Make clear, using the Committee Note as quoted above, that certain existing case law is “incorrect” and, thus, abrogated by the amendment.
• Cite the burden of proof. Emphasize that the burden is on the proponent of expert testimony to establish, by a preponderance of the evidence, each of the elements of the Rule 702 analysis. Cite not only the newly added language in the first paragraph of Rule 702 itself (requiring that “the proponent demonstrate[] to the court that it is more likely than not that” each element has been satisfied), but also the Committee Note’s emphasis that the burden applies to each of the “three reliability-based requirements added in 2000—requirements that many courts have incorrectly determined to be governed by the more permissive Rule 104(b) standard” just as it does to Rule 702’s other requirements, such as qualification and helpfulness.
• Highlight that opinions and methodology go hand in hand. Make clear that courts must not focus solely on an expert’s methodology without regard to the opinion that the methodology yields. Rule 702(d)’s new formulation clarifies that an expert’s opinion must reflect a reliable application of the expert’s methodology to the facts of the case. The Committee Note clarifies that this amendment “emphasize[s] that each expert opinion must stay within the bounds of what can be concluded from a reliable application of the expert’s basis and methodology. Judicial gatekeeping is essential because . . . jurors may [] be unable to assess the conclusions of an expert that go beyond what the expert’s basis and methodology may reliably support.”

If litigants consistently push these messages, courts may eventually iron out a consistent application of the Rule 702 amendments and take charge of their “essential” judicial gatekeeping function.