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 Georgia, the admissibility of expert witness testimony is governed by the Georgia Code and case law interpreting it. An individual may qualify as an expert witness if they possess specialized knowledge, skill, experience, training, or education that is pertinent to the issues in the case. The expert's testimony should be aimed at helping the court or jury understand complex evidence or resolve disputed fact issues. However, there is no strict formula for determining who qualifies as an expert; the key is that there must be a relevant connection between the expert's expertise and the subject matter of the dispute. The judge serves as a gatekeeper, tasked with ensuring that only reliable expert testimony is presented to the factfinder. This involves assessing the methods, principles, and reasoning the expert has used to ensure they are scientifically valid and applicable to the facts of the case. The judge has the discretion to exclude expert testimony that does not meet the standards of reliability and relevance.