What is an Expert Witness?

An Expert Witness is “one who is skilled in some art, science, trade, profession, or other human activity, and possesses peculiar knowledge concerning it.” (Black’s Law Dictionary 688. 4th Ed. Rev. 1968). Expert witnesses are able to testify in trial about things relating to their own specialized knowledge in a particular field. 

Unlike other witnesses in a trial, expert witnesses are able to testify as to their own knowledge outside of a case, whether than simply what they have heard or seen. For instance, a neurologist could be called into court to testify to a defendant’s brain injury. Expert witnesses are paid for their time in court as well, and can sometimes deliver their own conclusions based on their expertise. Other witnesses are not paid and can not provide opinions.

The current guidelines for expert witnesses were laid out in the case of Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). Expert witnesses must have utilized techniques or theories prior to trial that are well tested and accepted within the scientific community, and they must be reliable for an expert to give their conclusions. In concept, expert witnesses are able to give reliable and impactful testimony in a way that non-experts can not. There are also non-testifying expert witnesses who simply offer consultation and support prior to trial.