On December 1, 2023, the most significant changes in almost 25 years to the federal rule governing expert testimony (Federal Rule of Evidence 702) took effect. The changes to Rule 702 are shown below, with additions underlined and deletions indicated as strike-through text:
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 the proponent demonstrates to the court that it is more likely than not that:
- 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;
- the testimony is based on sufficient facts or data;
- the testimony is the product of reliable principles and methods; and
- the expert has reliably applied expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.
The first change clarifies that the proponent of expert testimony has the burden of establishing all four criteria by a preponderance of the evidence. “Some evidence” is not enough—the proponent must prove the expert’s methods are “more likely than not” reliable. As the Advisory Committee observed, “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).” The second change requires that the opinions offered by an expert reliably follow from the expert’s methodology. This is designed to address the problem of expert’s overstating or exaggerating the conclusions that can be drawn from applying a given method.
Expert testimony is critical in most construction, class action, and healthcare litigation cases. Going forward, litigants should expect courts to have a renewed focus on expert admissibility issues and their critical gatekeeping role. Litigants should be prepared for increased attention by courts to threshold expert admissibility questions and be prepared to establish and/or challenge that admissibility. Litigants should also be wary of case law that incorrectly applied the prior version of Rule 702.