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—and to exclude such testimony when it is not reliable.

In North Carolina, expert witness testimony is governed by rules that allow individuals with specialized knowledge, skill, experience, training, or education to provide their expert opinion in court. 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 case. The judge serves as a gatekeeper, assessing the appropriateness of the expert's testimony, ensuring that it is pertinent to the case and based on a reliable foundation. The judge has the discretion to admit or exclude expert testimony, and this decision is guided by the need to provide the factfinder with reliable and useful information to make informed decisions.