Abstract: Historically, the civil procedures in England and Wales follow an adversarial approach. The criminal procedures started to develop an adversary system only in the 18th century. Since medieval times, the law system has grappled with issues as to when and how to use expert knowledge to assist it in the resolution of disputes. The earliest records of expert witness date back to the 14th century and involve cases in which surgeons were summoned to establish as whether a wound was fresh. The role of an expert witness is to assist the court on matters within their expertise. Courts rely on expert witness testimony in most civil and criminal cases to explain scientific matters that may not be understood by the judge or the jury. It is especially important for the dentist to demonstrate confidence in his testimony especially during the cross-examination. Above all the expert witness should keep in mind during the time of intensive interrogation that it is not him on trial even though it may seem to be at some times.