A witness who qualifies as an expert because of knowledge, skill, experience, training, or education may testify as an expert if scientific, technical, or other specialized knowledge will assist the judge, jury, or other factfinder to understand the evidence or determine a contested fact issue.

But there is no rigid formula for determining whether a particular witness is qualified to testify as an expert. Generally there must be a fit between the subject matter at issue and the expert witness’s familiarity with the subject matter. And this determination is made by the judge, who acts as a gatekeeper to only allow reliable expert witness testimony to be heard and considered by the judge or jury.

In West Virginia, as in many jurisdictions, the admissibility of expert witness testimony is governed by rules that require the expert to have specialized knowledge, skill, experience, training, or education that is pertinent to the case at hand. The purpose of expert testimony is to help the judge or jury understand complex evidence or resolve disputed fact issues. The determination of whether a witness qualifies as an expert is not based on a strict formula but rather on the relevance and reliability of the witness's expertise in relation to the subject matter of the dispute. The judge serves as a gatekeeper, ensuring that only expert testimony that is pertinent and reliable is presented to the factfinder. This gatekeeping role involves assessing the proposed testimony's relevance to the issues in the case and the expert's qualifications. The judge must ensure that the expert's methods are properly applied to the facts of the case and that the testimony is more helpful than confusing to the jury. This standard is in line with the principles established in the landmark federal case Daubert v. Merrell Dow Pharmaceuticals, which has influenced the standards for expert witness testimony in both federal and state courts.