In Be Alert for the “Hybrid” Witness Editor-in-Chief of Daubert Online Patrick J. Kenny writes:
Though generally straightforward, the expert disclosure provisions of Rule 26 do contain “gray” areas with respect to which counsel should be alert. For instance, parties must disclose the identity of all witnesses they might use at trial to present evidence under Rules 702, 703 or 705 of the Federal Rules of Evidence. Fed. R. Civ. P. 26(a)(2)(A). If such a witness either is retained or specially employed to provide expert testimony, or if the witness’s job duties as a party’s employee regularly involve giving expert testimony, the disclosing party also must provide a written report prepared and signed by the expert containing certain information specified in Rule 26(a)(2)(B). Whether and to what extent the report requirement applies to a non-retained witness who also happens to qualify as an expert on some topic, a so-called “hybrid” witness, is not as clear.
The 1993 Advisory Committee Notes to Rule 26 do not provide much guidance. They note that the report requirement of Rule 26 “applies only to those experts who are retained or specially employed to provide such testimony in the case or whose duties as an employee of a party regularly involve the giving of such testimony.” Id. advisory committee’s notes (subdivision (a)(2)). Thus, a “treating physician, for example, can be deposed or called to testify at trial without any requirement for a written report.” Id. What is not as clear, though, are the topics on which a non-retained witness who otherwise could provide expert opinion testimony (such as a treating physician), but who did not prepare a Rule 26 report, may testify at trial.