3d Cir. Model Jury Instr. (Criminal) 4.08

“expert” witness is about to offer opinion testimony. When lay witnesses are permitted to offer

an opinion, use Instruction 4.09 (Opinion Evidence (Lay Witnesses)). If both expert and lay

witnesses are permitted to give opinion testimony, both sets of instructions should be given.

These instructions avoid 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’ opinion, and will protect against the jury’s being

“overwhelmed by the so-called ‘experts’.” 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). See also Fed. R. Evid. 702 advisory

committee’s note (2000) (cautioning against instructing the jury that the witness is an “expert”).

Before the beginning of trial, the judge should discuss with counsel that they should also

avoid using the word “expert” to refer to the witnesses. However, if counsel refers to witnesses

as “experts,” the trial judge should modify the instruction by telling the jury what an “expert” is.

Therefore, the court should include, after the first paragraph of the model instruction set forth

above, the following additional paragraph:

The defendant’s lawyer/the prosecutor called (Mr.) (Ms.) (Dr.) (name) an expert witness.

Someone who is called an expert witness is simply a witness who, because of his or her

knowledge, skill, experience, training, or education, may have become knowledgeable in

some technical, scientific, or specialized field and therefore is permitted to state an

opinion about that field. You should not give any greater weight or credit to (Mr.) (Ms.)

(Dr.) (name)’s testimony merely because he or she was called an expert witness by the

lawyers.

See 1A O’Malley et al., supra, § 14.01, 248-49.

Fed. R. Evid. 703 provides that facts or data which 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. In that situation, the comment to

the 2000 amendments to the rule states: “If the otherwise inadmissible information is

admitted under this balancing test, the trial judge must give a limiting instruction upon

request, informing the jury that the underlying information must not be used for

substantive purposes.” See Pineda v. Ford, 520 F. 3d 237, 247 n. 14 (3d Cir. 2008) (civil

case discussing Rule 703 limiting instruction) It must be noted, however, that permitting

an expert to base their opinion on the testimonial out-of-court statements of a non-testifying expert may violate the defendant’s right to confrontation. See Smith v. Arizona,

144 S. Ct. 1785 (2024); Bullcoming v. New Mexico, 564 U.S. 647, 661, 131 S.Ct. 2705,

180 L.Ed.2d 610 (2011); Melendez-Diaz v. Massachusetts, 557 U.S. 305, 320 n.6, 129

S.Ct. 2527, 174 L.Ed.2d 314 (2009).

(Revised 2025)