§ 7-4. Opinion Testimony by Experts; Bases of Opinion Testimony by Experts; Hypothetical Questions
7-4. Opinion Testimony by Experts; Bases of Opinion Testimony by Experts; Hypothetical Questions
(a) Opinion testimony by experts. An expert may testify in the form of an opinion and give reasons therefor, provided sufficient facts are shown as the foundation for the expert's opinion.
(b) Bases of opinion testimony by experts. The facts in the particular case upon which an expert bases an opinion may be those perceived by or made known to the expert at or before the proceeding. The facts need not be admissible in evidence if of a type customarily relied on by experts in the particular field in forming opinions on the subject. The facts relied on pursuant to this subsection are not substantive evidence, unless otherwise admissible as such evidence.
(c) Hypothetical questions. An expert may give an opinion in response to a hypothetical question provided that the hypothetical question (1) presents the facts in such a manner that they bear a true and fair relationship to each other and to the evidence in the case, (2) is not worded so as to mislead or confuse the jury, and (3) is not so lacking in the essential facts as to be without value in the decision of the case. A hypothetical question need not contain all of the facts in evidence.