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Law 101: Legal Guide for the Forensic Expert

Rules of Evidence and Lay Witnesses

Federal Rules of Evidence refer to the body of evidentiary rules, used in federal court and adopted in many state courts, which generally constitute a summary of the law of evidence in many jurisdictions.

FRE 701 applies to opinion evidence given by a lay (non-expert) witness. Lay witnesses cannot give opinions based on scientific, technical or specialized knowledge. In order for a non-expert witness to give an opinion in court, it must relate to something about which the witness has personal knowledge (e.g., eyewitness evidence) or be based on something upon which any reasonable person could offer an opinion (e.g., the height of a suspect).

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