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Determining whether experience-based opinion should be evaluated as lay or as expert opinion has proven particularly challenging to the courts. The Federal Rules of Evidence were amended in 2000, adopting specific, more stringent requirements for expert testimony and hardening the line between lay and expert opinion. Expert opinion testimony is admissible only if based on reliable methodology, whereas lay opinion must be rationally derived using everyday reasoning. The decisions applying the rules do not strike the right balance in regard to experience-based opinion. Too often, courts either accept claims of experience-based expertise at face value or admit experience-based opinion as lay opinion without rigorously applying the governing rule. As a result, they admit unreliable and unwarranted opinion testimony. This Article explains why more experience-based opinion should be evaluated as lay opinion and also argues for increased scrutiny of such lay opinion. Only a witness who has a reliable and specialized mode of analysis and has applied it to a reliable basis should be granted the latitude accorded an expert. A witness who merely applies everyday reasoning to draw inferences based on experience and observations should be constrained by the rules that govern lay opinion. This Article suggests five guidelines for the admissibility of experience-based opinion: 1) the court should generally determine the admissibility of the opinion under the rules governing lay opinion; 2) the court should be skeptical of claims that the witness possesses expertise based on experience and "training," understanding that the combination of experience and training does not necessarily signal that the witness brings reliable methodology to bear on the facts; 3) to determine the admissibility of experience-based opinion, the court should scrutinize the fit between the witness' experience and the proffered opinion; 4) the court should strictly limit opinion testimony that draws inferences based on third party conduct; and 5) the court should preclude witnesses from over-generalizing based on their experience.

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