Rule 615 Experts

Rule 615 of the Rules of Evidence, often called "the Rule" authorizes upon request for prospective witnesses to be excluded from the court while other witnesses are testifying.  However, there is an important exception to this.  Experts are allowed to stay if their presence is is essential to the presentation of the cause.  This is contained in the comments to the Rule and often overlooked.  The theory is that the expert often has to base his or her testimony on information received from various witnesses.  As a result, their opinion can change based upon the information received.