In Be Alert for the “Hybrid” Witness Editor-in-Chief of Daubert Online Patrick J. Kenny writes:
Still other courts hold that no report is required from a hybrid witness, regardless of the nature of the opinion testimony they will provide, if they were not “retained or specially employed” to provide expert testimony. E.g., Denson v. Northeast Ill. Regional Commuter Railroad Corp., No. 00 C 2984, 2003 WL 1732984 at *1 (N. D. Ill. Mar. 31, 2003) (“There is no indication that any of the three treating physicians from whom plaintiff may elicit expert opinions was retained or specially employed for that purpose. Therefore, the report requirement does not apply for their testimony.”).
Though hybrid witness issues most often arise with respect to testimony from treating physicians, they also plainly can arise in other contexts as well. See, e.g., St. Paul Mercury Ins. Co. v. Capitol Sprinkler Inspection, Inc., 246 F.R.D. 56, 59 (D.D.C. 2007) (allowing a hybrid witness to testify as to “information gained in his role as Executive General Adjuster with respect to the incident in question” but not to “offer his independent opinions regarding causation, or damages assessments made either after litigation commenced or independent of his assessment of damages as a function of his job as an insurance adjuster”).