Unlike nonexpert witnesses, who usually must state only factors and not opinions, expert witnesses are called to testify for the sole purpose of stating expert opinion about some specific part of the case. Experts must possess education, training, licensing, or board certification, as well as specific experience within their area of avowed expertise, obtained through experience on the job. Many self-described experts are not actually qualified, because they have been self-taught or claim to be experts in many disciplines. However, they are sometimes allowed to testify due to the lack of knowledge of the prosecution or defense counsel or the court. The prosecutor or defense attorney who engages an expert should not try to dictate or influence the formation of the expert's opinion. To testify credibly, experts must develop their interpersonal communication skills. They must also stand above reproach at all times. Finally, they must recognize the need to establish standards and goals of excellence, as well as to adhere to them if they are to remain professionals. 4 references