[4] ARTICLE VII. OPINIONS AND EXPERT TESTIMONY

Rule 701. Opinion by Lay Witness

During their testimony, a lay witness’s opinion must be…

• rationally based on the witness’s perception

• helpful to understand the witness’s testimony

• helpful to determine a fact in issue

• not based on scientific, technical, or other specialized knowledge within Rule 702

Rule 702. Testimony by Expert Witness

An expert witness’s testimony may be admitted by the court if they determine that…

• the witness is an expert by knowledge, skill, experience, training, or education

• the appropriateness of the expert testimony on the subject

• there is a sufficient factual basis that supports the expert testimony

Rule 703. Bases of an Expert (Typical Usage)

If an expert witness’s opinion is based on facts and data that are typically used in their field, they are admissible.

Rule 703. Bases of an Expert (Non-typical Usage)

If an expert witness’s opinion is based on facts and data that are not typically used in their field, they may only be admissible if the jury finds the information more probative than prejudicial.

Rule 704. Opinion on the Ultimate Issue (In General)

An expert witness’s opinion on the ultimate issue is not objectionable because it embraces the ultimate issue.

Rule 704. Opinion on the Ultimate Issue (Mental State or Condition)

In a criminal case, an expert witness may not state their opinion on the defendant’s mental state or condition that meets an element of the crime.

Rule 705. Disclosing the Facts or Data Underlying an Expert

Unless the court requires otherwise, an expert witness may state an opinion without first stating the underlying facts or data.

They may be required to disclose on cross-examination.