expert witness reports

Expert witness reports in civil federal court are governed by Federal Rule of Civil Procedure 26(a)(2)(b). Under this rule, the parties are required to disclose the names of their retained expert witnesses before trial, and to give the opposing party a written report, prepared and signed by the expert witness. Unless stipulated or otherwise ordered by the court, this report must contain: 

A complete statement of all of their opinions the expert will provide, and the basis and reasons for those opinions; 

  1. The facts or data considered by the witness in forming those opinions; 
  2. Any exhibits that will be used by the expert to summarize their opinions, or to support them; 
  3. The witness's qualifications, including a list of all publications authored by the expert in the previous 10 years; 
  4. A list of all of the cases that expert testified either at deposition or at trial, during the previous four years; and 
  5. A statement of the expert’s compensation for their research and testimony in the case.  

The purpose of this rule is to provide notice to opposing counsel before the deposition as to how that expert will testify. As such, experts can be precluded from testifying if their reports are too vague, or if they are written with conclusionary statements without a supporting basis for their conclusions. See, e.g., Moore v. International Paint L.L.C., 547 F. App'x 513 (5th Cir. 2013) (expert excluded after the expert’s report did not meet Rule 702 standards).

It is not sufficient for an expert to state that they will provide an opinion on an issue. Rather, that opinion must be stated in the report, along with their supporting reasoning. Experts can also be prevented from providing testimony that is beyond the scope of their original report. In general, if an expert did not provide an opinion in a report created pursuant to Rule 26(a), that expert will not be able to testify about it at trial. 

Federal Rule 26(b)(4)(B) expressly protects as work product drafts of designated expert reports. Rule 26(b)(4)(C) protects as work product communications between attorneys and experts, except those relating to compensation, facts or data provided by the attorney that the expert “considered in forming the opinions to be expressed,” or relating to assumptions provided by the attorney and “relied on” by the expert.  

As to non-testifying experts, under Federal Rule 26(b)4)(D) a party may not ordinarily engage in discovery directed to consulting experts retained in anticipation of litigation. Discovery in such circumstances is only allowed in “exceptional circumstances” when it is “impracticable . . . to obtain facts or opinions on the same subject by other means.”

Rule 16(a)(1)(G) and (b)(1)(C) of the Federal Rules of Criminal Procedure, outline the expert witness disclosure requirements in federal criminal cases. There are corresponding provisions for the government Rule (16(a)(1)(G)) and the defendant Rule (16(b)(1)(C)) which require the expert to provide a “written summary of any testimony” which includes the “witness’s opinions, the bases and reasons for those opinions, and the witness’s qualifications.”

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