Also known as: reliability gate-keeping · gatekeeping reliability · Daubert reliability · expert reliability screening
Written by attorneys · grounded in primary & secondary sources — see below
The judicial obligation to determine whether expert testimony rests on reliable principles and methods before it reaches the jury. The inquiry is flexible and case-specific, extending to all forms of specialized knowledge rather than being limited to laboratory science.
Riverstone Manufacturing offers a telecom engineer to explain what a reasonably designed backup system would have included after a network failure. The engineer bases his opinions on internal incident logs and a personal checklist rather than published industry protocols. The court must still decide whether those materials supply a sufficiently reliable foundation for the testimony to reach the jury.
Riverfront Developments calls a veteran banker to describe how institutional investors evaluate complex derivatives. The banker relies on industry heuristics and informal surveys drawn from years of market practice. The court conducts a reliability review to decide whether those methods are trustworthy enough for the jury even though they lack statistical validation.
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No. The obligation extends to every witness who offers testimony based on scientific, technical, or other specialized knowledge. Courts must therefore screen engineering, accounting, and experience-based opinions under the same flexible standard that governs laboratory science.
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The absence of those traditional markers does not automatically require exclusion. The court may instead consider other indicia such as the expert's depth of experience, whether the approach is common in the field, and whether it was applied reliably to the facts of the case.
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A court may exclude the testimony when the gap is too great. The judge evaluates whether the expert's reasoning bridges the data to the opinion in a trustworthy way, and the decision receives abuse-of-discretion review on appeal.
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Admission is possible only if the methodology still satisfies the flexible reliability standard. When the method was invented solely for the case, lacks external validation, and rests on unquantified subjective judgments, exclusion is ordinarily required.
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