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 Connecticut, expert witnesses are permitted to testify in legal proceedings if their specialized knowledge, skills, experience, training, or education can help the court understand the evidence or decide on a contested issue of fact. The state does not adhere to a strict formula for qualifying an expert witness. Instead, the key consideration is the relevance and fit between the expert's expertise and the subject matter of the case. The determination of whether a witness is qualified as an expert is made by the presiding judge, who serves as a gatekeeper to ensure that only reliable and pertinent expert testimony is presented to the judge or jury. This gatekeeping function is crucial to maintaining the integrity of the legal process and ensuring that the fact-finding is based on sound and credible expert insights.