A witness that has expertise in a certain field.(noun)
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Use "expert witness" in a sentence
"Psychiatric malpractice suits represent only a small percentage of malpractice cases, according to John J. Lucas, M.D., clinical assistant professor of psychiatry at Weill Medical College at Cornell University, and expert witness in malpractice cases."
"And Bob Shoop, a Kansas State University education professor and expert witness in thirty court cases involving sexual abuse in schools, summed it up this way: I think our society sort of says to the boy: ‘Congratulations, that’s great."
"Psychiatrist Harrison Pope of McLean Hospital in Massachusetts sometimes serves as an expert witness in court."