On December 1, 2023, Rule 702 of the Federal Rules of Evidence, which governs testimony by expert witnesses in federal court, was amended to require a preponderance of the evidence standard. As explained by the Committee Notes, the rule “has been amended to clarify and emphasize 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.” The Committee Notes further emphasize that the rule change was necessary because “many 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)” and that “emphasizing the preponderance standard in Rule 702 specifically was made necessary by the courts that have failed to apply correctly the reliability requirements of that rule.” The amended rule now reads as follows (new language is underlined and deleted language is struck through):

Rule 702

“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 has reliably applied expert’s opinion reflects a reliable application of 

    the principles and methods to the facts of the case.”

With this amendment and its clarified “preponderance of the evidence” standard, going forward, litigants should be mindful of the stricter evaluation by federal courts of any proposed expert testimony but also that this new amendment provides a stronger basis to challenge unreliable experts. 

If you have any questions about the amendment to Rule 702, or about Leader Berkon Colao & Silverstein’s litigation practice, please contact us. We will provide updates regarding any further developments with the amendment to Rule 702 and its application.