Lay Opinion & Expert Testimony

Question 1

General Rule for Lay Witness Testimony

Answer 1

Law witness are only to testify in the form of facts, not opinions

Question 2

Law witness opinion testimony

Answer 2

If a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is

1) rationally based on the witness’s perception;
2) helpful to clearly understand the witness’s testimony or to determine a fact in issue; and
3) not based on scientific, technical, or other specialized knowledge within the scope of expert testimony.

Question 3

Qualifying as an Expert

Answer 3

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

1) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
2) the testimony is based on sufficient facts or data;
3) the testimony is the product of reliable principles and methods; and
4) the expert has reliably applied the principles and methods to the facts of the case

Question 4

Opinions on Ultimate Issues

Answer 4

1) an opinion is not objectionable just because it embraces an ultimate issue.

2) in a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have the mental state or condition that constitutes an element of the crime charged or defense.

NOTE - experts may not offer opinions on the credibility of witnesses or state legal conclusions

Question 5

Proper Factual Basis for Expert Testimony

Answer 5

1) expert witness’s own personal knowledge of the facts

2) facts or data that the expert is made aware of at trial

3) facts or data the expert review prior to trial, if experts in the particular field would reasonably rely on these kinds of facts or data in forming an opinion

If the facts or data would otherwise be inadmissible, the proponent of the option may disclose them to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect.

NOTE - an adverse party may cross examine about the underlying facts or data

Question 6

Learned Treatise Hearsay Exception

Answer 6

A statement contained in a treatise, periodical, or pamphlet is admissible if:

1) the statement is called to the attention to an expert witness on cross examination or relied on by the expert on direct examination; and

2) the publication is established as a reliable authority by the expert’s admission or testimony by another expert or by judicial notice.

If admitted, the statement may be read into evidence but not received as an exhibit.