Witnesses

Question 1

Expert Witnesses

Answer 1

Under Federal Rule 702, expert opinion testimony is admissible if the subject matter is one where scientific, technical, or other specialized knowledge would help the trier of fact understand the evidence or determine a fact in issue.

This test of assistance to the trier of fact subdivides into two requirements:

(i) The opinion must be relevant, and
(ii) The methodology underlying the opinion must be reliable.

To testify as an expert, a person must have special knowledge, skill, experience, training, or education su

Question 2

Lay Witnesses

Answer 2

under the Federal Rules, opinion testimony by lay witnesses is admissible when it is:
(i) rationally based on the perception of the witness;
(ii) helpful to a clear understanding of her testimony or to the determination of a fact in issue; and
(iii) not based on scientific, technical, or other specialized knowledge.

Matters involving sense recognition, such as what something smelled like, are common subjects of opinion testimony.

Question 3

Expert Witness Basis for Opinion

Answer 3

An expert’s opinion may be based on one or more of the following sources of information: (i) facts that he knows from his own observation,
(ii) facts presented in evidence at the trial and submitted to the expert, or (iii) facts not in evidence that were supplied to the expert out of court and which are of a type reasonably relied upon by experts in the particular field in forming opinions on the subject.