The sequestration of expert witnesses in Illinois falls under the Illinois Rules of Evidence, Rule 615. Ct. Rules Ill. Comp. Stat. 6/615 (West 2017). This rule requires that a witness be excluded from the courtroom if a party requests or the court orders on its own. Id. The rule has four exceptions of individuals that cannot be excluded, and experts fall under the third exclusion. Id. The third exclusion is for “a person whose presence is shown by a party to be essential to the presentation of the party’s cause.” Id. The trial judge is given the discretion to determine whether a witness should be excluded or not. People v. Chennault, 181 N.E.2d 74 (Ill. 1962).
