An expert witness is a special kind of witness in court who, due to their training and experience, is able to provide their opinion to the court on the implications of evidence before the court.
Daubert's general holding -- setting forth the trial judge's general "gatekeeping" obligation -- applies not only to testimony based on "scientific" knowledge, but also to testimony based on "technical" and "other specialized" knowledge. See Fed. Rule Evid. 702.
As the U.S. Supreme Court held: {{cquote|[A] trial court may consider one or more of the more specific factors that Daubert mentioned when doing so will help determine that testimony's reliability. But, as the Court stated in Daubert, the test of reliability is "flexible," and Daubert's list of specific factors neither necessarily nor exclusively applies to all experts or in every case. Rather, the law grants a district court the same broad latitude when it decides how to determine reliability as it enjoys in respect to its ultimate reliability determination. Kumho Tire Co. v. Carmichael, 526 U.S. 137, 141-42 (1999).