Expert Witness Services

Expert witnesses are specialists in a particular field of study who are hired to analyze data related to a court case. They are not witnesses in the usual sense, as they are typically hired by the participating attorneys to provide a well thought out analysis of the evidence, rather than simply giving testimony of an event.

In many cases, a decision is made based solely on firsthand evidence, rendering an expert witness unnecessary. However, cases often require expertise in a certain field of study beyond common knowledge that can only be provided by a professional in that field. Expert witnesses work with both officers and lawyers to translate the evidence into a testimony that can be understood in layman’s terms.

Most expert witnesses are drawn from the medical field and the engineering field (Johnson, 2000). Doctors, physicians, and psychologists are commonly utilized in the criminal field due to the prevalence of crimes resulting in injury or death. Medical experts may resolve a conflict as small as insurance fraud or as grand as a murder investigation. Engineers are more common in civil courts, in which they determine the outcome of cases that often involve tort law, insurance, or car accidents.

Impartial Experts

The greatest complaints against utilizing an expert witness are that the expert becomes biased toward one party over the other, and that they are too expensive to hire. It is up to each party to determine if the expert is worth the expense, while it is the judge’s duty to determine the objectivity and permissibility of the expert’s testimony, as it is possible that the information the expert has to offer is irrelevant, biased, or in conflict with previously submitted evidence.

However, there are several safeguards against bias to ensure the testimony is valid.

In most cases, expert witnesses are expected to provide credentials that certify them as an authority in their field of study. Diplomas, licenses, and certificates ensure that the expert witness has a reliable foundation on which to build their testimony.

Another way to prevent bias is to make their payment independent of the outcome of the case. Expert witnesses, unlike lawyers, are paid whether their client wins the case or not, as conditional payment would encourage the expert to manipulate their analysis in favor of their client. Experts are also encouraged to maintain a professional distance from their clients in order to prevent an emotional attachment to the situation.


Johnson, Molly Treadway. "Expert Witness in Federal Civil Trials." 2000.http://www.fjc.gov/public/pdf.nsf/lookup/ExpTesti.pdf/$file/ExpTesti.pdf (accessed April 23, 2010).

Hill, Gerald N.. "Expert Witness Legal Definition." 2005.http://legal-dictionary.thefreedictionary.com/Expert+witnesses (accessed April 23, 2010).

Casarez, Jean. "Expert Explains "Black Box" at Trooper Trial." May 22, 2009.http://insession.blogs.cnn.com/2009/05/22/expert-explains-black-box-at-trooper-trial/ (accessed April 23, 2010).