When does expert testimony cross from insightful to misleading? Delve into the case of Gilmore v. Jefferson County, where the Washington Supreme Court navigated complex evidence rules to exclude biomechanical expert Alan F. Tencer. This article explores the balance courts must strike between an expert's insights and the need for factual clarity, offering valuable lessons for legal practitioners. Discover how expert testimony's reliability and relevance are meticulously scrutinized in courtrooms, impacting both plaintiffs and defendants.