Also known as: gatekeeper functions · gate-keeping function · gatekeeper role · gatekeeper · gatekeepers
Written by attorneys · grounded in primary & secondary sources — see below
A judicial screening role that requires a court to determine whether proffered expert testimony is both relevant and reliable before it reaches the trier of fact. Reliability is evaluated through a flexible, case-specific inquiry that may consider whether the expert's theory or method has been tested, subjected to peer review and publication, shown to have a known or potential error rate, governed by controlling standards, or generally accepted in the relevant field.
Gloria Green offers a toxicologist who concludes that Glacier Energy's emissions caused her respiratory illness. The district court holds a hearing and finds the expert's methodology untested and lacking peer review or known error rates. The court excludes the testimony, preventing it from reaching the jury.
George Garcia proffers an epidemiologist linking PCBs from Great Lakes Steel to his lung cancer. The court examines the studies cited and concludes an analytical gap exists between the data and the expert's causation conclusion. The testimony is excluded as unreliable.
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Gina Griffin offers a tire analyst who attributes a blowout to a manufacturing defect based on visual inspection alone. The court applies the gatekeeper role to this technical testimony and finds the method lacks sufficient validation or standards. The opinion is excluded.
Glenn Gross seeks to introduce an engineer's reconstruction of a product failure. The court conducts a pretrial hearing and determines the expert's principles and their application to the facts are not shown to be reliable by a preponderance. The testimony is barred from trial.
No. The function extends to all expert testimony, including technical and other specialized knowledge, not merely novel scientific theories. A court must therefore assess the reliability of a tire-failure analyst's methodology even though it rests on experience rather than laboratory science.
The proponent must demonstrate by a preponderance of the evidence that the expert is qualified and that the opinion reflects a reliable application of principles and methods to the facts of the case. The court performs this screening before the evidence reaches the jury.
No. The court cannot abdicate the screening function or allow the jury to decide reliability questions. Doing so would defeat the purpose of ensuring only relevant and reliable expert testimony is admitted.
…failed Rule 702's reliability requirement. The court agreed with Kumho that it should act as a Daubert -type reliability "gatekeeper," even though one might consider Carlson's testimony as "technical," rather than "scientific." See Carmichael v. Samyang Tires, Inc. , 923 F. Supp. 1514, 1521-1522 (SD Ala. 1996). The…