7-2 RELIABILITY OF EXPERT WITNESS TESTIMONY GENERALLY

• Jurisdiction: United States

7-2 Reliability of Expert Witness Testimony Generally

Federal Rule of Evidence 702 establishes the general standard for the admissibility of expert testimony at trial: "[i]f scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise."¹ The evidentiary standard under the Texas Rules of Evidence is identical.²

Under these rules, it is the trial court's responsibility to "ensure the reliability and relevancy of expert testimony."³ This gatekeeping requirement "is to make certain that an expert, whether basing testimony on professional studies or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field."⁴ The U.S. Supreme Court has established several nonexclusive factors to assist trial courts in determining reliability, including (1) whether the theory can be (or has been) tested; (2) whether the theory has been subject to peer review and publication; (3) the theory's potential rate of error; (4) the application of standards and controls to the theory; and (5) whether the theory is generally accepted.⁵ By contrast, an expert's opinion is considered unreliable if there is too great a gap between the data relied upon and the opinion, the foundational data is unreliable, or if the expert draws conclusions from sound data based on flawed methodology.⁶ To be clear, "[t]he test for determining reliability is flexible and can adapt to the particular circumstances underlying the testimony at issue."⁷ The party offering the expert testimony has the burden of showing that the expert testimony is reliable.⁸

Beyond relevance and reliability, an expert must be qualified to testify on the topic on which he or she offers testimony. "Before a district court may allow a witness to testify as an expert, it must be assured that the proffered witness is qualified to testify by virtue of his 'knowledge, skill, experience, training, or education.'"⁹ Indeed, "[a] district court should refuse to allow an expert witness to testify if it finds that the witness is not qualified to testify in a particular field or on a given subject."¹⁰ Under Rule 702, qualification as an expert can come in many forms, including through general experience in the industry at issue...