Understanding the distinction between expert and lay testimony is vital for anyone involved in a criminal case in Utah. Whether you are the defendant, a lawyer, or a concerned party, knowing how these forms of testimony influence a case can make all the difference. This guide delves into the critical differences, the roles of expert and lay witnesses, and their importance in Utah courtrooms.
Expert testimony is provided by individuals with specialized knowledge, training, or experience in a particular field. Their insights go beyond what the average person might understand and often address scientific, technical, or professional matters.
Lay witnesses offer testimony based on their personal perceptions and experiences. Unlike expert witnesses, their opinions must be rationally based and helpful to understanding facts in the case. According to Utah Rule of Evidence 701, lay testimony does not require specialized knowledge.
Under Utah Code §77-17-13 (2025), strict guidelines regulate expert witness disclosures:
Utah Rule of Evidence 702 is critical to admitting expert testimony. It reads:
Rule 702. Testimony by Experts.
Effective: 11/1/2007
(a) Subject to the limitations in paragraph (b), 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 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.
(b) Scientific, technical, or other specialized knowledge may serve as the basis for expert testimony only if there is a threshold showing that the principles or methods that are underlying in the testimony
(b)(1) are reliable,
(b)(2) are based upon sufficient facts or data, and
(b)(3) have been reliably applied to the facts.
(c) The threshold showing required by paragraph (b) is satisfied if the underlying principles or methods, including the sufficiency of facts or data and the manner of their application to the facts of the case, are generally accepted by the relevant expert community.
Rule 701 Opinion testimony by lay witnesses.
Rule 702 Testimony by experts.
Rule 703 Bases of opinion testimony by experts.
Rule 704 Opinion on ultimate issue.
Rule 705 Disclosing the Facts or Data Underlying an Expert’s Opinion.
Rule 706 Court-appointed experts.
In complex cases, expert testimony can be pivotal. For instance, a forensic psychologist’s explanation of memory distortion can challenge a key witness’s credibility. Similarly, accident reconstructionists help juries visualize events that might otherwise be unclear. Leveraging these experts effectively can strengthen your defense.
Practical Tip: Always disclose your expert witnesses on time to avoid trial delays or sanctions.
Lay testimony remains equally crucial in many cases. A witness’s firsthand account of events can paint a vivid picture for the jury. For example, a bystander’s description of a defendant’s behavior at the scene can reinforce or refute other evidence.
Facing criminal charges in Utah? Understanding the role of expert and lay testimony could make or break your case. At Provo Criminal Defense, we specialize in crafting strong defense strategies that utilize the right witnesses to protect your rights. Contact us today at (801) 373-6345 for a free consultation, or visit Provocriminaldefense.com to learn more.