expert witness

expert witness

n. a person who is a specialist in a subject, often technical, who may present his/her expert opinion without having been a witness to any occurrence relating to the lawsuit or criminal case. It is an exception to the rule against giving an opinion in trial, provided that the expert is qualified by evidence of his/her expertise, training and special knowledge. If the expertise is challenged, the attorney for the party calling the "expert" must make a showing of the necessary background through questions in court, and the trial judge has discretion to qualify the witness or rule he/she is not an expert, or is an expert on limited subjects. Experts are usually paid handsomely for their services and may be asked by the opposition the amount they are receiving for their work on the case. In most jurisdictions, both sides must exchange the names and addresses of proposed experts to allow pre-trial depositions. (See: expert testimony)

expert witness

in the law of evidence, a witness who is allowed to give opinion evidence as opposed to evidence of his perception. This is the case only if the witness is indeed skilled in some appropriate discipline. An exception to the usual rule of practice whereby witnesses are heard one after the other and do not hear the evidence of the preceding witness is made in relation to competing experts. The term skilled witness is favoured in Scotland.