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Law 101: Legal Guide for the Forensic Expert

Use of an Expert Witness at Trial

Use of an Expert Witness at Trial
National Institute of Justice (NIJ) (see reuse policy).

Expert Opinion Testimony

The expert plays a special function in the trial process. The forensic analyst's right to testify is based on the need of the fact finder for some specialized knowledge beyond that of the average juror.

The general standard for expert testimony is whether "scientific, technical or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue" (FRE 702). If the fact finders (usually jurors but, in some cases, judges) already have the basic knowledge at issue, there is no need for an expert to testify in that capacity.

Once the above standard is met, it must be shown that the particular expert is qualified. Qualifications may come from a variety of sources: "by knowledge, skill, experience, training, or education" (FRE 702).

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