What is an Expert Witness?

An expert witness is a witness, who by virtue of education, training, skill, or experience, is believed to have knowledge in a particular subject beyond that of the average person, sufficient that others may officially (and legally) rely upon the witness’s specialized (scientific, technical, or other) opinion about an evidence or fact issue within the scope of their expertise, referred to as the expert opinion, as an assistance to the fact-finder. Expert witnesses may also deliver expert evidence about facts from the domain of their expertise. At times, their testimony may be rebutted with a learned treatise, sometimes to the detriment of their reputations.

Typically, experts are relied on for opinions on severity of injury, degree of insanity, cause of failure in a machine or other device, loss of earnings, care costs, and the like. In an intellectual-property case, an expert may be shown two music scores, book texts, or circuit boards and asked to ascertain their degree of similarity.

The tribunal itself, or the judge, can in some systems call upon experts to technically evaluate a certain fact or action, in order to provide the court with a complete knowledge on the fact/action it is judging. The expertise has the legal value of an acquisition of data. The results of these experts are then compared to those by the experts of the parties.

The expert has a heavy responsibility, especially in penal trials, and perjury by an expert is a severely punished crime in most countries.

The Role Of An Expert Witness & Their Benefits:
The role of expert witnesses is to bring clarity to the court. In cases covering complex subjects, it is often advisable to retain an expert witness. The expert has a number of roles. First, he or she consults with the attorney regarding the merits of the case. Second, the expert is charged with reviewing all the evidence and authoritative subjects on the matter. Third, the expert is charged with rendering an opinion regarding the subject. Fourth, the expert witness has the task of explaining a complex subject in such a way that the court can readily understand it.

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