A member of both the District of Columbia and Oklahoma Bar Associations, Duke Ligon of Oklahoma City is an attorney focused on energy law. Admitted to the US Court of Appeals for the second and fifth circuits, Duke Ligon of Oklahoma City is an expert witness for the Federal Courts on Board Governance.
Evidence law confines testimonies of witnesses in both criminal and civil cases to concrete statements of fact that the witnesses observed, know, and can recall. The law limits testimonies to facts as perceived or observed by the witnesses using their natural senses. The witness is precluded from giving their opinions, impressions, and inferences, or from drawing conclusions; if in that case, the fact-finders are competent enough to form their own conclusions and opinions.
There are cases, however, when the law provides for witnesses to give opinion evidence. This is in the case of lay opinions and expert opinions.
Lay witnesses may give their opinions if the opinion is rational with regard to their senses, if it will help the fact-finders understand the testimony, and if it is not centered around scientific or specialized knowledge.
Expert witnesses, on the other hand, are people qualified by experience or study to form opinions in the fields of science, art, or a specific trade. The law disqualifies people without special training or experience in technical areas, deeming them incapable of giving accurate opinions with regard to technical matters.
Therefore, a person with qualified skill, expertise, or education in a technical or scientific area may give his or her opinion or form a conclusion as a testimony if it is based on sufficient and reliable scientific data, whose principles the witness has reliably applied to the material case.