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 Alabama, expert witnesses are individuals who, due to their knowledge, skill, experience, training, or education, may provide testimony in court on matters that require scientific, technical, or specialized knowledge. The purpose of such testimony is to help the judge or jury understand the evidence or to make a decision on a contested fact. The determination of whether a witness qualifies as an expert does not follow a strict formula; instead, it requires an assessment of whether there is an appropriate match between the witness's expertise and the subject matter of the case. The judge serves as a gatekeeper in this process, with the responsibility to ensure that only reliable expert testimony is presented to the court. This gatekeeping role involves evaluating the relevance and reliability of the expert's testimony before it is permitted to be heard by a judge or jury.