<P> An expert witness , in England , Wales and the United States , is a person whose opinion by virtue of education , training , certification , skills or experience , is accepted by the judge as an expert . The judge may consider the witness 's specialized ( scientific , technical or other ) opinion about evidence or about facts before the court within the expert 's area of expertise , referred to as an `` expert opinion '' . Expert witnesses may also deliver `` expert evidence '' within the area of their expertise . Their testimony may be rebutted by testimony from other experts or by other evidence or facts . </P>
who gives expert view on the facts in their area of their expertise
An expert witness