You are here

2.13 Expert Opinion

Printer-friendly version
2.13 Expert Opinion

            You [have heard] [are about to hear] testimony from [name] who [testified] [will testify] about [his] [her]opinions and the reasons for those opinions. This opinion testimony is allowed, because of the specialized knowledge, skill, experience, training, or education of this witness.

            Such opinion testimony should be judged like any other testimony. You may accept it or reject it and give it as much weight as you think it deserves, considering the witness’s specialized knowledge, skill, experience, training, or education, the reasons given for the opinion, and all the other evidence in the case.



            See Fed. R. Evid. 702-05.

            According to Federal Rule of Evidence 702, "[t]he purpose of expert testimony is to ‘assist the trier of fact to understand the evidence or to determine a fact in issue’ by providing opinions on ‘scientific, technical, or other specialized knowledge.’ " Wagner v. County of Maricopa, 701 F.3d 583, 589 (9th Cir.2012) (quoting Fed. R. Evid. 702). Under Federal Rule of Evidence 703, an expert’s opinion must be based on facts or data in the case that the expert has been made aware of or personally observed. Fed. R. Evid. 703. The facts and data need not be admissible so long as experts in the particular field would reasonably rely on such facts and data. Id.

            This instruction avoids labeling the witness as an "expert." If the court refrains from designating the witness as an "expert," this will "ensure[] that trial courts do not inadvertently put their stamp of authority" on a witness’s opinion and will protect against the jury’s being "overwhelmed by the so-called ‘experts.’" See Fed. R. Evid. 702 advisory committee’s note (2000) (quoting Hon. Charles Richey, Proposals to Eliminate the Prejudicial Effect of the Use of the Word "Expert" Under the Federal Rules of Evidence in Criminal and Civil Jury Trials, 154 F.R.D. 537, 559 (1994).

            In addition, Fed. R. Evid. 703 (as amended in 2000) provides that facts or data that are the basis for an expert’s opinion but are otherwise inadmissible may nonetheless be disclosed to the jury if the court determines that their probative value in assisting the jury to evaluate the expert’s opinion substantially outweighs their prejudicial effect.

This instruction is appropriate for a witness who provides only expert opinion testimony. If the same witness provides expert opinion testimony and percipient witness testimony (whether fact testimony, lay opinion testimony, or both), these different roles should be clarified for the jury, even in a civil case. Model Criminal Instruction 3.15 (Dual Role Testimony) provides guidance.

Revised Mar. 2023