Also known as: Daubert standard · Daubert rule · Daubert hearing · Daubert · Daubert v. Merrell Dow
Written by attorneys — see sources below.
A judicial standard used by federal courts to determine the admissibility of expert testimony under Federal Rule of Evidence 702. The standard requires the trial judge to act as gatekeeper by ensuring that the testimony is both relevant and reliable through a flexible case-specific inquiry into the expert's principles and methods.
Damian Decker sued Dixon Foods after a delivery truck rollover injured him. Dixon Foods offered an aerospace engineer who relied on a proprietary fluid-dynamics simulation never validated against actual crash data. The district court conducted a pretrial hearing and excluded the testimony because the methodology lacked testing and a known error rate for real-world applications.
Destiny Davis sued Dakota Industries for patent infringement over a facial-recognition algorithm. Dakota Industries offered a computer scientist whose benchmarking script rested on unreviewed internal tests and laptop extrapolations. The district court excluded the testimony after finding an impermissible analytical gap between the limited data and the opinions offered.
Diane Dawson sued Dawson Steel after an industrial press severed her hand. Dawson Steel offered a mechanical engineer who relied on a finite-element computer model never independently validated. The district court admitted the testimony after determining that the flexible reliability inquiry supported the technical methodology.
Dolores Diaz challenged a state's execution protocol. The state offered a pharmacy dean to testify about a sedative's properties. The district court performed a Daubert analysis and admitted the testimony after concluding the expert's qualifications and methods met the reliability threshold.
Oklahoma has long used a three-drug protocol for executions. The first drug, a barbiturate, is intended to induce a state of unconsciousness. The second drug, a paralytic, is intended to paralyze the inmate and stop breathing. The third drug, potassium chloride, is intended to stop the heart. In 2009, Oklahoma began using a three-drug protocol consisting of sodium thiopental, pancuronium bromide, and potassium chloride. In 2010, after the sole American manufacturer of sodium thiopental announced that it would no longer produce the drug, Oklahoma began using pentobarbital in place of sodium thiopental. In 2013, after that manufacturer also ceased production of pentobarbital, Oklahoma announced that it would use midazolam in place of the barbiturate. On January 15, 2014, Oklahoma executed Charles Warner using the new protocol. Warner had filed a §1983 action challenging the constitutionality of Oklahoma’s lethal injection protocol, but the District Court denied his motion for a preliminary injunction, and the Court of Appeals for the Tenth Circuit affirmed. On the day of Warner’s execution, petitioners, all Oklahoma death row inmates, filed a §1983 action in federal district court. They contended that the use of midazolam in Oklahoma’s execution protocol violates the Eighth Amendment because it is incapable of rendering a person insensate to pain. In December 2014, after discovery, the District Court held a 3-day evidentiary hearing on the preliminary injunction motion. The District Court denied the motion for a preliminary injunction. The Court of Appeals for the Tenth Circuit affirmed. Oklahoma executed Warner on January 15, 2015, but the Supreme Court subsequently stayed the executions of Glossip, Cole, and Grant pending the resolution of this case.
View caseDaniel Diaz faced court-martial charges. He sought to introduce polygraph results through an examiner. The military judge excluded the testimony after determining that the technique failed the reliability requirements for specialized knowledge.
In March 1992, Edward G. Scheffer, an airman stationed at March Air Force Base in California, volunteered to work as an informant on drug investigations for the Air Force Office of Special Investigations. His OSI supervisors advised him that they would ask him to submit to drug testing and polygraph examinations from time to time during his undercover work. In early April, one of the OSI agents supervising Scheffer requested that he submit to a urine test. Shortly after providing the urine sample, but before the results were known, Scheffer agreed to take a polygraph test administered by an OSI examiner, who concluded that the test indicated no deception when Scheffer denied using drugs since joining the Air Force. On April 30, Scheffer unaccountably failed to appear for work and could not be found on the base. He remained absent without leave until May 13, when an Iowa state patrolman arrested him following a routine traffic stop and held him for return to the base. OSI agents later learned that Scheffer's urinalysis revealed the presence of methamphetamine. Scheffer was tried by general court-martial on charges of using methamphetamine, failing to go to his appointed place of duty, wrongfully absenting himself from the base for 13 days, and, with respect to an unrelated matter, uttering 17 insufficient funds checks. At trial Scheffer testified on his own behalf, relying upon an innocent ingestion theory and denying that he had knowingly used drugs while working for OSI. On cross-examination the prosecution attempted to impeach him with inconsistencies between his trial testimony and earlier statements he had made to OSI. Scheffer sought to introduce the polygraph evidence in support of his testimony that he did not knowingly use drugs, but the military judge denied the motion and excluded the evidence pursuant to Military Rule of Evidence 707. Scheffer was convicted on all counts and sentenced to a bad-conduct discharge, confinement for 30 months, total forfeiture of all pay and allowances, and reduction to the lowest enlisted grade. The Air Force Court of Criminal Appeals affirmed in all material respects. By a 3-to-2 vote the United States Court of Appeals for the Armed Forces reversed. The Supreme Court granted certiorari.
View caseDwight Dorsey was prosecuted for drug trafficking. The government offered an agent's interpretation of recorded statements. The district court excluded the testimony after finding the agent's methodology created too great an analytical gap from the underlying data.
A deputy sheriff stopped Reginald Harris's rental car for weaving on the highway. Harris consented to a search that uncovered 19 kilograms of cocaine in two suitcases in the trunk, leading to his immediate arrest. Shortly after the arrest, DEA Special Agent Donald Walton interviewed Harris by telephone. Harris stated that he obtained the cocaine from an unidentified Cuban in Fort Lauderdale, that the cocaine belonged to petitioner Fredel Williamson, and that it was to be delivered to a particular dumpster that night. Physical evidence also connected Williamson to the car: the luggage bore the initials of Williamson's sister, Williamson was listed as an additional driver on the rental agreement, and an envelope addressed to Williamson along with a receipt bearing his girlfriend's address were found in the glove compartment. Several hours later, Agent Walton spoke with Harris in person. Harris explained that he had rented the car a few days earlier, driven it to Fort Lauderdale to meet Williamson, and received the cocaine from a Cuban acquaintance of Williamson along with a note instructing him on the delivery. Harris repeated that he was to leave the drugs in a dumpster, return to his car, and depart without waiting. When Agent Walton prepared to arrange a controlled delivery, Harris admitted he had lied about the Cuban, the note, and the dumpster. He stated instead that he was transporting the cocaine to Atlanta for Williamson, who was traveling ahead in another rental car, and that Williamson had driven past the stop and seen the police searching the trunk. Harris explained he had lied out of fear of Williamson and refused to have his statement recorded or to sign a written version, though Walton promised to report any cooperation to the prosecutor. At Williamson's trial on charges of possessing cocaine with intent to distribute, conspiring to possess cocaine with intent to distribute, and traveling interstate to promote the distribution of cocaine, Harris refused to testify despite receiving use immunity and being held in contempt. The District Court admitted Agent Walton's testimony about Harris's statements under Federal Rule of Evidence 804(b)(3), finding them against Harris's penal interest, Harris unavailable, and sufficient corroboration present. The Court of Appeals for the Eleventh Circuit affirmed the conviction without opinion, and the Supreme Court granted certiorari.
View caseThe trial judge must act as gatekeeper to ensure expert testimony is both relevant and reliable before it reaches the jury. The judge conducts a preliminary assessment of the expert's methodology outside the jury's presence, typically during a Daubert hearing.
No. The reliability analysis extends to all expert testimony based on technical or other specialized knowledge. Courts retain discretion to consider the traditional factors or other appropriate indicia of reliability tailored to the field.
Appellate courts review a district court's decision to admit or exclude expert testimony for abuse of discretion. A court may exclude testimony when there is too great an analytical gap between the data and the opinion proffered.
No. The factors are illustrative and flexible rather than a rigid checklist. A court may consider testability, peer review, error rate, standards, and general acceptance, but need not require every factor when the methodology is otherwise reliable for its field.