Also known as: gatekeepers · gatekeeping · gatekept · gate keeper
Written by attorneys · grounded in primary & secondary sources — see below
A judicial function requiring the trial court to screen proffered expert testimony to ensure it is both relevant and reliable before it reaches the factfinder. Reliability is evaluated through a flexible inquiry that may examine whether the expert's theory or method has been tested, subjected to peer review, shown to have a known error rate, governed by standards, or generally accepted in the field. The court may also exclude an opinion when an analytical gap exists between the data and the conclusion offered.
Gustavo Gutierrez sued Genesis Pharmaceuticals after developing a severe reaction to a new medication. Genesis offered a toxicologist who relied on an internal company study never published or tested outside the firm. The district court excluded the testimony after finding the methodology lacked external validation and could not be shown reliable under the governing standard.
Georgia Gibbs sued Gateway Bank after claiming exposure to chemicals caused her illness. Her expert relied on animal studies and general literature but offered no direct link to the specific compounds at issue. The district court excluded the opinion, concluding the analytical gap between the cited data and the proffered conclusion was too wide.
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Gary Goldman sued Gulfstream Aviation after a tire blowout caused an accident. His engineering expert applied a visual inspection method never subjected to peer review or error-rate analysis. The district court performed its screening function and excluded the testimony for lack of demonstrated reliability.
Appellate courts review a district court's decision to admit or exclude expert testimony for abuse of discretion. The trial judge's gatekeeping determinations receive substantial deference because they are case-specific and involve weighing multiple reliability factors.
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The obligation extends to all expert testimony based on technical or other specialized knowledge. Courts may consider the Daubert factors or any other appropriate indicia of reliability when screening non-scientific expertise.
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A court may examine whether the expert's theory 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. These factors are flexible and not a rigid checklist.
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A court may exclude an opinion when the gap between the data relied upon and the conclusion offered is too great. The expert's conclusions must be supported by sufficient facts and a reliable methodology.
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…by people who deal in these matters, see, e.g., Gross Aff. at 5. The Court held, however, that federal judges perform a "gatekeeping role," Daubert , --- U.S. at ----, 113 S.Ct. at 2798; to do so they must satisfy themselves that scientific evidence meets a certain standard of reliability before it is admitted. This…