Also known as: FRE 703 · Fed. R. Evid. 703 · Federal Rule of Evidence 703 · Rule of Evidence 703
Written by attorneys · grounded in primary & secondary sources — see below
A rule permitting an expert to base an opinion on facts or data in the case that the expert has been made aware of or personally observed. If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion, the facts or data need not be admissible for the opinion to be admitted. When the facts or data would otherwise be inadmissible, the proponent may disclose them to the jury only if their probative value in helping the jury evaluate the expert's opinion substantially outweighs their prejudicial effect.
Rhea Reynolds, a forensic toxicologist, reviewed a lab report prepared by another technician showing the presence of a controlled substance in a blood sample. She formed her opinion that the substance caused impairment even though she lacked personal knowledge of the testing procedures. The court admitted her opinion because toxicologists reasonably rely on such reports, and the report itself was not offered for its truth.
Roberto Reyes, a DNA analyst, based his opinion linking a defendant to a crime scene on a profile generated by an outside laboratory. He did not personally perform the underlying testing. The court permitted the opinion because analysts in the field reasonably rely on accredited lab profiles, allowing the jury to assess the weight of the basis evidence.
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Disclosure is permitted only if the probative value in helping the jury evaluate the expert's opinion substantially outweighs the prejudicial effect. This reverse balancing test makes disclosure on direct examination rare.
Supporting sources
Rule 703 allows experts to rely on facts or data they have not personally observed, including hearsay, when such information is of a type reasonably relied upon by experts in the field. Lay witnesses must have personal knowledge under Rule 602, and that rule expressly does not apply to expert testimony under Rule 703.
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The facts or data must be of a type reasonably relied upon by experts in the particular field. Courts examine whether professionals in that field customarily use such information in forming opinions, even if the information would be inadmissible hearsay.
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No. The rule expressly allows an expert to base an opinion on inadmissible facts or data provided experts in the field would reasonably rely on them. The opinion itself may be admitted even though the underlying facts or data are not.
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…he had the opportunity to cross-examine the expert who had testified as to the match. The prosecutor argued that Illinois Rule of Evidence 703 permitted an expert to disclose facts on which the expert’s opinion is based even if the expert is not competent to testify to those underlying facts, and that any deficiency went to the…