Also known as: scientific methods · Daubert factors
Written by attorneys · grounded in primary & secondary sources — see below
An analytical technique by which a hypothesis is formulated and then systematically tested through observation and experimentation. In the law of evidence the technique supplies the foundation for assessing whether an expert's theory or methodology is reliable.
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Maria Lopez sued Apex Pressworks after a factory press crushed her hand. Apex offered a mechanical engineer who relied on proprietary modeling software and personal inspections to conclude the safety guard design was adequate. The court conducted a flexible reliability inquiry and admitted the testimony because the engineer's methods were shown to rest on tested principles and were reliably applied to the machine at issue.
Harbor Ridge Partners sued Zephyr Wind Corp. alleging low-frequency turbine noise caused health problems. Zephyr offered an acoustics consultant whose hybrid method combined short-term sound measurements with subjective annoyance surveys. The court applied a flexible reliability analysis to the technical methodology and admitted the testimony after finding the approach grounded in accepted acoustic principles and properly applied to the wind farm conditions.
After an armed robbery the police conducted a lineup in which the defendant stood among several fillers. The defense challenged the identification procedure as unreliable. The court examined whether the identification process incorporated systematic testing and controlled standards akin to the scientific method and found the procedure sufficiently reliable to admit the resulting testimony.
In a DUI prosecution the state offered a lab analyst's report on the defendant's blood alcohol level obtained through gas chromatography. The defense objected that the analyst who performed the test did not testify. The court assessed whether the underlying scientific method was reliable and whether the testifying witness could adequately explain the controlled standards and error rate before admitting the results.
Plaintiffs sued a pharmaceutical company alleging a design defect in a prescription drug. The defendant offered expert testimony based on internal testing protocols that had not been published or subjected to external validation. The court evaluated whether the testing methodology satisfied the requirements of the scientific method and excluded the testimony because the protocols lacked known error rates and independent verification.
No. The reliability inquiry under Rule 702 extends to all expert testimony based on scientific, technical, or other specialized knowledge. Courts apply a flexible, case-specific analysis that may consider the Daubert factors or other appropriate indicia of reliability for engineering, technical, and experience-based expertise.
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…nothing less than whether the experts' testimony reflects "scientific knowledge," whether their findings are "derived by the scientific method," and whether their work product amounts to "good science." --- U.S. at ----, ----, 113 S.Ct. at 2795, 2797. Second, we must ensure that the proposed expert testimony is "relevant to the…
…The Criminal Lineup at Home and Abroad, 1966 Utah L. Rev. 610, 621-627. [^maj-30]: Thirty years ago Wigmore suggested a "scientific method" of pretrial identification "to reduce the risk of error hitherto inherent in such proceedings." Wigmore, The Science of Judicial Proof 541 (3d ed. 1937). Under this approach, at least 100…
…but Part IV of this opinion. JUSTICE THOMAS joins all but Part IV and footnote 6. [^maj-2]: Gas chromatography is a widely used scientific method
…a critical element of admissibility. See, e.g., State v. Temple , 302 N.C. 1, 273 S.E.2d 273, 280 (1981) (evidence based on new scientific methods
No. The Daubert factors are illustrative considerations that guide but do not rigidly control the admissibility determination. A court may admit testimony when the methodology rests on tested principles, has been published, or can be tested through cross-examination even if some factors are not fully met.
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Peer review and publication are relevant but not mandatory factors. Their absence does not automatically render testimony inadmissible when other indicia such as testing, known error rates, or industry validation demonstrate that the methodology is reliable and was reliably applied to the facts.
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Lay opinion is admissible only if it is rationally based on the witness's perception and does not depend on scientific, technical, or other specialized knowledge. When a witness draws conclusions that require systematic testing, controlled standards, or specialized methodology, the testimony crosses into expert territory and must satisfy Rule 702 reliability requirements.
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