Can a Treating Physician’s Medical Testimony Be “Lay Opinion”? Divided Sixth Circuit Panel Disagrees on Where to Draw the Line

Federal Rules of Evidence 701 and 702 govern the admissibility of lay and expert opinion testimony, respectively, in federal courts. Rule 701(c) helps paint the line between the two, providing that an opinion “based on scientific, technical, or other specialized knowledge within the scope of Rule 702” cannot be admitted as a lay opinion. This requirement was added in the 2000 Amendments to Rule 701 to address what the Advisory Committee described as a risk “that the reliability requirements set forth in Rule 702 will be evaded through the simple expedient of proffering an expert in lay witness clothing.” Given this history, one might expect courts to err toward applying Rule 702 to any testimony that inherently draws on expertise that laypeople do not possess. But, as illustrated by the Sixth Circuit’s split decision in United States v. Betro, --- F.4th ---, 2024 WL 3811838 (6th Cir. 2024), some courts use a different approach.