non-testifying expert witnesses

A non-testifying expert witness is an individual possessing specialized knowledge, skills, and experience relevant to a particular case “who has been retained or specially employed by another party in anticipation of litigation or to prepare for trial and who is not expected to be called as a witness at trial." Federal Rule of Civil Procedure 26(b)(4)(D)

Under Rule 26(b)(4), a party may employ two types of experts: 

  1. Those experts identified as "an expert whose opinions may be presented at trial" which the court will refer to as a "testifying" expert; and 
  2. Experts "retained or specially anticipation of litigation or to prepare for trial and who [are] not expected to be called as a witness at trial," which the court will refer to as a "non-testifying" or "consulting" experts.”

Unlike a testifying expert witness who provides expert testimony, the non-testifying expert primarily works in an advisory capacity, offering consultation and support to legal teams during pre-trial preparations. Their analysis helps attorneys identify relevant information, potential gaps, or inconsistencies, ensuring that the legal team is well-prepared to address any challenges that may arise during trial.

Discovery is limited for non-testifying expert witnesses. An opposing party may "discover facts known or opinions held by" non-testifying expert only "as provided in Rule 35(b) (physical and mental examinations)" or "on showing exceptional circumstances under which it is impracticable for the party to obtain facts or opinions on the same subject by other means." Rule 26(b)(4); see also Downs v. River City Group, LLC, (2013) 288 F.R.D. 507

In general, communications between a non-testifying expert, attorney, and client are protected from disclosure by attorney-client privilege. See U.S. v. Kovel, 296 F.2d 918 (2nd Cir. 1961). 

There are instances in which a non-testifying expert’s opinion may not be protected. For instance, if a consulting expert discloses their opinion to a third party who lacks a common legal interest, attorney-client privilege could be waived. See U.S. Postal Service v. Phelps Dodge Refining Corp., 825 F. Supp. 156 (E.D.N.Y. 1994). 

[Last updated in August 2023 by Jim Robinson Esq., JurisPro Expert Witness Directory]