Lay and Expert Testimony

When is lay witness opinion testimony admissible?

A lay witness’s opinion testimony is admissible when it is: (1) rationally based on the witness’s perception; (2) helpful to the case; and (3) not based on scientific, technical, or specialized knowledge.

When is expert opinion testimony admissible?

Expert testimony is admissible if:

(1) witness is qualified as an expert;

(2) opinion is helpful to the case;

(3) opinion is based on sufficient facts and data;

(4) opinion is based on reliable principles and methods; and

(5) opinion reflects facts of this case.

When can a witness be qualified as an expert?

A witness may be qualified as an expert if they possess specialized knowledge, skill, training, or education.

When would an expert opinion be helpful to the case?

The expert opinion is helpful if it is more likely than not that the subject matter is one where scientific, technical, or specialized knowledge would help the understanding of the jury.

When are fact sufficient for an expert to render an admissible opinion?

(1) facts personally observed by the expert;

(2) facts made known to the expert at trial; or

(3) facts supplied to the expert outside of the courtroom and of a type reasonably relied on by experts in the field.

How is the reliability of principles and methodologies determined?

Courts use the following Daubert factors to determine the reliability of the principles and methodologies used by the expert:

(1) testing of principles or methodologies;

(2) rate of error;

(3) acceptance by experts in the field;

(4) peer review and publications

(NOTE: TRAP mnemonic)