What does the "Opinion Exclusionary Rule" determine?

The Opinion Exclusionary Rule is a legal principle that governs the circumstances under which witness opinions can be presented in a court of law. It specifically relates to the distinction between lay opinions and expert opinions.

This rule determines that only qualified individuals, often referred to as expert witnesses, can provide opinions that require specialized knowledge, training, or experience. Expert opinions are admissible if they are relevant to the case and based on reliable methodologies. This ensures that the jury or judge is guided by credible information that aligns with the standards of the field in question.

In contrast, lay witnesses—those without specialized expertise—may only give testimony based on their perceptions and experiences without providing opinions that require specialized knowledge. Understanding the purpose of the Opinion Exclusionary Rule helps clarify the conditions under which evidence can be introduced during trials and supports maintaining the integrity of the judicial process.