Fed. R. Civ. P. 26(a)(2)(B)(ii) governs testifying experts' duty to produce "the facts or data considered by the witness in forming" his or her opinion. Fed. R. Civ. P. 26(b)(4)(D) governs dramatically different non-testifying consulting experts. Not surprisingly, witnesses might switch from one role to the other, and also might possess arguably pertinent facts from direct or tangential participation in the pertinent underlying events. This type of expert is commonly called a "dual-hat" expert, whose involvement can raise subtle issues.
In Johns v. CR Bard (In re Davol, Inc.), Case Nos. 2:18-md-2846 & 2:18-cv-1509, 2021 U.S. Dist. LEXIS 105022 (S.D. Ohio June 4, 2021), plaintiff alleged injuries from hernia mesh complications. Plaintiff hired Dr. Nagy as a non-testifying consulting expert, and later designated him as a testifying expert — but refused to produce documents he created while reviewing defendants' documents. The court ordered plaintiff to produce those documents. First, "[e]ven crediting Plaintiff's contention that Dr. Nagy was a consulting witness initially," the court ruled that "[t]he proponent of a dual-hat expert, i.e.[,] an expert that is both a consulting and testifying expert" may only withhold "'materials generated or considered uniquely in the expert's role as [non-testifying] consultant.'" Id. at *11-12 (citation omitted). The court explained that Dr. Nagy "'cannot be expected to draw a mental line in the sand between information gleaned' in an earlier, consulting context and information later learned as a testifying expert when the subject matter is so similar." Id. at *12 (internal citation omitted). The court also noted that the testifying expert rule requires such experts to produce "all materials reviewed or considered by the expert, whether or not the expert report ultimately refers to those materials as a basis for his or her opinions." Id. at *6 (citation omitted). The court emphasized that "[a]mibiguities are resolved in favor of discovery." Id.
Litigants often retain an expert first as a non-testifying consulting expert — to be sure that the litigant likes the expert's conclusions, demeanor, etc. But litigants must carefully consider what such an expert might be required to produce upon morphing into a testifying expert. Next week's Privilege Point will address a "dual-hat" expert scenario another court addressed about two weeks later.