What is Expert Witness Testimony?

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  • Written By: N. Madison
  • Edited By: Jenn Walker
  • Last Modified Date: 25 February 2020
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An expert witness is a person who testifies in court, using his expertise to provide testimony on behalf of the defense or prosecution. The testimony he gives is called expert witness testimony. An expert witness does not testify because he is personally involved in a case, has special knowledge of the details of a case, or receives a subpoena. Instead he testifies after being asked to by the prosecution or defense. An expert witness can accept these requests when he’s interested in testifying and refuse them when he’s not.

A person is considered qualified to offer expert witness testimony when he has specialized education, training, knowledge, experience, and skills that are relevant to a court case. This education, skill, or knowledge may make him qualified to answer factual questions posed during a court case. For example, a pharmacy expert may testify about the composition of certain medicines. An expert witness can also provide an opinion in a court case, however. For example, he may testify about whether or not he believes a particular medication could cause the death of an otherwise healthy person.

Before choosing a particular expert witness, an attorney carefully evaluates his qualifications. If the person’s qualifications are not suitable, his expert witness testimony may not be taken seriously in court. A judge may even refuse to allow him to testify.


Besides considering a potential witness’ experience or training, an attorney will usually evaluate his skill as well. Expert witnesses need excellent communication skills in order to answer questions clearly and ensure that their answers can be understood by those who do not share their experience. They must also be skilled at analyzing facts, some of which may be complex. This type of witness should also be strong enough to stay firm and under control when questioned by the attorney on the opposing side.

An expert witness’ job doesn’t start when he enters a courtroom and begins to provide expert witness testimony. Before going into court, he will usually meet with the attorney who has requested his services to review the case. This is intended to not only provide the facts of the case for the expert to consider, but also to make sure his opinion matches the attorney’s position on the case. If the expert disagrees with the attorney’s conclusions, he won’t be helpful for the attorney’s client once they enter a courtroom. As such, the attorney will usually need to select a different expert.



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