Before an expert may testify, the court conducts a gatekeeping function under Daubert (or Frye in some state courts) to ensure the testimony is both relevant and reliable. The offering party must qualify the witness as an expert, typically through voir dire about credentials. Opposing counsel may challenge the expert's qualifications, methodology, or the application of the methodology to the specific facts. Experts may rely on facts or data not admitted into evidence if they are of a type reasonably relied upon by experts in the field. Common expert witnesses include forensic scientists, medical professionals, economists, accident reconstructionists, and digital forensics analysts.
Attorney: "Dr. Chen, please state your qualifications." Witness: "I hold a Ph.D. in biomechanics from MIT, have published 47 peer-reviewed articles on vehicle crash dynamics, and have testified as an expert in over 30 cases." Attorney: "Your Honor, I tender Dr. Chen as an expert in biomechanics and crash reconstruction."
Opposing Counsel: "Your Honor, I request a Daubert hearing. The methodology this expert used — extrapolating from a sample size of three — has never been peer-reviewed and has no known error rate." Judge: "We'll schedule a hearing outside the presence of the jury."
Attorney: "Dr. Ramirez, based on your examination and review of the medical records, do you have an opinion to a reasonable degree of medical certainty regarding the cause of the plaintiff's injuries?" Expert: "Yes. In my opinion, the herniated disc at L4-L5 was caused by the rear-end collision."
Students often assume experts must have academic credentials. Rule 702 also qualifies experts through skill, experience, or training. A mechanic with 30 years of experience may qualify as an expert on engine failure without any formal degree. Additionally, the Daubert standard applies in federal court, while some states still use the older Frye "general acceptance" test.
Federal courts follow the Daubert standard (1993) for expert admissibility under FRE 702, requiring scientific reliability. Some states still use the older Frye "general acceptance" test (e.g., California, Illinois, Pennsylvania), leading to significantly different expert qualification outcomes.
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)
Replaced the Frye "general acceptance" test with a multi-factor reliability analysis for scientific expert testimony, establishing the trial judge as gatekeeper under Rule 702.
Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999)
Extended the Daubert gatekeeping framework to all expert testimony, including non-scientific testimony based on technical or specialized knowledge.
General Electric Co. v. Joiner, 522 U.S. 136 (1997)
Established that appellate courts review trial court Daubert rulings under the deferential abuse-of-discretion standard, giving trial judges broad latitude in gatekeeping decisions.
| Daubert (Federal Courts) | Frye (Some State Courts) |
|---|---|
| Multi-factor reliability test | Single "general acceptance" test |
| Judge acts as gatekeeper evaluating methodology | Judge asks only if method is generally accepted |
| Applies to all expert testimony (after Kumho) | Applies primarily to novel scientific evidence |
| Flexible, non-exclusive factors | Binary: accepted or not accepted |
| Codified in Rule 702 (amended 2000) | Common law standard from 1923 |
| Adopted by federal courts and majority of states | Still used in some states (e.g., California, New York) |
What is the Daubert standard for expert testimony?
The Daubert standard requires federal courts to act as gatekeepers, ensuring expert testimony is both relevant and reliable. Courts consider factors including whether the theory can be tested, peer review and publication, known error rates, existence of standards, and general acceptance in the scientific community.
What is the difference between Daubert and Frye standards?
The Daubert standard (federal courts) evaluates reliability through multiple factors and gives judges discretion as gatekeepers. The Frye standard (some state courts) requires only that the methodology be "generally accepted" in the relevant scientific community. Daubert is considered more flexible and comprehensive.
Can an expert testify based on experience alone without academic credentials?
Yes, Rule 702 qualifies experts through "knowledge, skill, experience, training, or education." A witness with extensive practical experience in a field can qualify as an expert without formal academic credentials, provided their testimony meets reliability requirements.
What can an expert witness rely on in forming their opinion?
Under Rule 703, experts may rely on facts or data not admitted into evidence if they are of a type reasonably relied upon by experts in that field. This allows experts to base opinions on hearsay, reports from others, and data that would otherwise be inadmissible, provided the reliance is reasonable.
Foundation refers to the preliminary showing that must be made before evidence is admitted. It estab...
Evidence is relevant if it has any tendency to make a fact of consequence more or less probable than...
Direct examination is the initial questioning of a witness by the party who called that witness to t...
Voir dire is the process by which prospective jurors are questioned to determine their qualification...
