Ohio R. Evid. 704
Testimony in the form of an opinion or inference otherwise admissible is not objectionable solely because it embraces an ultimate issue to be decided by the trier of fact.
Ohio. R. Evid. 704
Staff Note (July 1, 2006 Amendment)
Rule 704 differs from Federal Evidence Rule 704 in only one regard. The word "solely" has been added after the word "objectionable" to clarify the thrust of the rule.
The rule does not serve to make opinion evidence on an ultimate issue admissible; it merely provides that opinion evidence on an ultimate issue is not excludable per se. The rule must be read in conjunction with Rule 701 and Rule 702, each of which requires that opinion testimony be helpful to, or assist, the trier of the fact in the determination of a factual issue. Opinion testimony on an ultimate issue is admissible if it assists the trier of the fact, otherwise it is not admissible. The competency of the trier of the fact to resolve the factual issue determines whether or not the opinion testimony is of assistance.
The rule is in accordance with Ohio law as it has developed prior to the adoption of the Rules of Evidence.
The general rule in Ohio as to the admissibility of opinion evidence on an ultimate issue was stated in the first two paragraphs of the syllabus in the case of Shepherd v. Midland Mutual Life Ins. Co. (1949), 152 OS 6, 39 OO 352, 87 NE2d 156, as follows:
Although a witness may be qualified to give an opinion concerning a matter upon which opinion evidence may be admissible in and pertinent to the determination of an issue, as a general rule such an opinion, whether expert or otherwise, may not be admitted when it, in effect, answers the very question as to the existence or nonexistence of an ultimate fact to be determined by the jury.
Where an ultimate fact to be determined by the jury is one depending upon the interpretation of certain scientific facts which are beyond the experience, knowledge or comprehension of the jury, a witness qualified to speak as to the subject matter involved may express an opinion as to the probability or actuality of a fact pertinent to an issue in the case, and the admission of such opinion in evidence does not constitute an invasion or usurpation of the province or function of the jury, even though such opinion is on the ultimate fact which the jury must determine.
The exception extends to lay opinion testimony as well as to expert opinion testimony. A lay witness may not render an opinion as to the capacity of a testator to make a will, Runyan v. Price (1864), 15 OS 1, but a lay witness may testify as to the capacity to form an intent to dispose of property by a will. Dunlap, Exr., v. Dunlap (1913), 89 OS 28, 104 NE 1006; Weis v. Weis (1947), 147 OS 416, 34 OO 350, 72 NE2d 245. The same example as to capacity is utilized in the Advisory Committee Note to Federal Evidence Rule 704 to illustrate that the effect of the rule is not to admit all opinion on the ultimate issue, but to assure that helpful opinion on the ultimate issue is not automatically excluded.