Expert Opinion Evidence - National Judicial Institute

Note: Specimen jury instructions serve as a template that trial judges must adapt to the particular circumstances of each trial, not simply read out in whole. They are not designed to be delivered "as-is." More information about the use of specimen instructions is found in the Preface and A Note to Users, which you can find here.

7.18 Expert Opinion Evidence

(Last revised March 2011)

[1] Normally, witnesses may only testify about what they have seen or heard, and may not testify about their opinions. In the case of (NOW), however, because of his/her special training, education and experience, s/he will be permitted to give an opinion about (specify).

[2] Although (NOW) will be permitted to give his/her opinion, it is up to you to decide the extent to which you will rely on it. Here are some things to consider as (NOW) testifies:

§ (NOW)’s qualifications and experience;

§ the reasons given for the opinion;

§ the suitability of the methods used;

§ whether (NOW) is impartial; and

§ the other evidence in the case.

It is up to you to decide how much or little to rely on (NOW)’s opinion.

[3] (NOW) may be asked to assume or rely on certain facts in giving his/her opinion. Those facts may be the same or different from what you later find as facts on the basis of all the evidence in this case. The closer the facts assumed or relied on by (NOW) are to the facts as you find them to be, the more helpful (NOW)’s opinion may be to you. To the extent (NOW) relies on facts that you do not find supported by the evidence, you may find (NOW)’s opinion less helpful.