Rule 703 addresses the basis of expert opinions. Which statement is correct?

• A. An expert may base opinions on facts or data reasonably relied upon by experts in the field, even if those facts are not admitted into evidence.
• B. An expert's opinion must be based only on facts admitted into evidence.
• C. Experts may rely on rumors and speculation.
• D. An expert must have personally observed all facts.

Answer: (D)

Rule 703 lets an expert base an opinion on facts or data that would be reasonably relied upon by experts in the same field, even if those facts aren’t admitted into evidence. This reflects how professionals form conclusions in real life—they use data, tests, articles, or industry standards that the field normally considers when weighing an issue. As long as the type of data is something a reasonable expert would rely on, the opinion can stand on that foundation, even if the underlying materials aren’t in the courtroom record. The court may require disclosure of the underlying facts on cross-examination or for weighting, but the opinion itself can still be admitted.

This isn’t limited to facts admitted into evidence, and it doesn’t require the expert to have personally observed every fact. It also doesn’t permit basing opinions on rumors or speculation. For example, a forensic engineer might rely on lab test results or manufacturer specifications that aren’t themselves entered as evidence, so long as those sources are of the kind professionals in that field would reasonably rely upon to form an opinion.