Legal Memorandum: Admission of Opinion Evidence in Iowa

Issue: What are the rules regarding admission of opinion evidence under Iowa law?

The Iowa Rules of Evidence explicitly provide for admission of opinion testimony on an issue of fact that is to be decided by the jury.  Iowa R. Evid. 5.704 states that

Testimony in the form of an opinion or inference otherwise admissible is not objectionable because it embraces an ultimate issue to be decided by the trier of fact.

Although witnesses generally may not testify as to their opinions on ultimate legal conclusions, see, e.g. Smith v. Wright, 2014 Iowa App. LEXIS 560 (May 29, 2014) (unpublished), Iowa courts employ liberal rules allowing opinion testimony if it will aid the jury and is based on a witness’s special training, experience, or knowledge with respect to the issue in question.  Id.  The distinction between the ultimate factual issues on which opinion testimony may be offered and opinions on legal issues depends on whether the terms used by the witness to answer a question have separate, distinct, and specialized meanings in legal usage from the meanings in common parlance.  If the popular meaning of a term is roughly the same as the legal meaning, the opinion will not be excluded “merely because it contains legal terms.”  In re Palmer, 691 N.W.2d 413, 419 (Iowa 2005) (quoting 1 McCormick on Evidence § 12, at 56 (John W. Strong ed., 5th ed. 1999).

In Heinz v. Heinz, 653 N.W.2d 334, 341 (Iowa 2002), the court held that it was not error for the trial court to admit […]