Also known as:Federal Rule of Evidence 702 · FRE 702 · Rule 702 · Fed. R. Evid. Rule 702
Written by attorneys · grounded in primary & secondary sources — see below
A federal evidentiary rule that permits a witness qualified by knowledge, skill, experience, training, or education to offer opinion testimony. The proponent must show that the specialized knowledge will help the trier of fact understand the evidence or determine a fact in issue, that the testimony rests on sufficient facts or data, that it is the product of reliable principles and methods, and that the expert has reliably applied those principles and methods to the facts of the case.
Sources & Authorities· 8 primary sources
Select any source to read its text and confirm it supports the definition.
Cases
Federal Rules
Hornbooks
Study Supplements
How it applies
Common Examples
6
Disclosure of Retained Expert
Floyd Franklin sues Fisher Foods after suffering an allergic reaction to a packaged snack. Fisher Foods retains a toxicologist to testify about the product's ingredients and manufacturing process. Under the applicable disclosure rules, Fisher Foods must identify this witness to Franklin before trial so that the opposing party can prepare for the expert's opinions.
Distinguishing Lay from Expert Opinion
Fernando Farrell testifies that a warehouse floor appeared wet based on his direct observation of smearing patterns. When he begins to estimate how long the liquid had been present using specialized training in slip-and-fall analysis, the court requires him to satisfy the standards for expert testimony rather than permitting the opinion as ordinary lay testimony.
Gatekeeping Reliability Review
Faye Fuller offers a forensic economist to calculate damages in a securities fraud case using a novel event study with alternative market indices. The court examines whether the methodology has been tested, subjected to peer review, or shown to have a known error rate before deciding whether the testimony may reach the jury.
Subject Matter Disclosure
Forrest Falconer designates a network engineer to address redundancy failures in a telecommunications outage case. The disclosure must state the subject matter on which the engineer will present evidence so the opposing party receives adequate notice of the topics the expert will cover.
Technical Expertise Screening
Felicia Fuentes offers an entertainment production manager to testify about rigging standards after a stage collapse. The court applies reliability screening to this experience-based technical testimony even though it rests on industry practice rather than laboratory science.
Analytical Gap Between Data and Opinion
Farid Farahani offers a computer scientist who reviewed only marketing brochures and selected code snippets before concluding that one algorithm copies another. The court excludes the testimony because the limited data create too great a gap from the confident opinion offered on real-world performance.
General Electric Co. v. Joiner522 U.S. 166 (1997)
Common questions
Frequently Asked
4
What must a proponent demonstrate before expert testimony is admitted under the rule?+
The proponent must show that the expert is qualified, that the specialized knowledge will assist the trier of fact, that the testimony rests on sufficient facts or data, that it is the product of reliable principles and methods, and that the expert has reliably applied those methods to the facts of the case.
Supporting sources
Does the reliability requirement apply only to scientific experts?+
No. The requirement applies to all expert testimony based on scientific, technical, or other specialized knowledge, including engineering and experience-based opinions. Courts use a flexible, case-specific analysis that may draw on the traditional scientific factors or other appropriate indicia of reliability.
What role does the trial judge play when expert testimony is offered?+
The trial judge acts as gatekeeper and must ensure that the testimony is both relevant and reliable before it reaches the jury. The judge evaluates the soundness of the expert's principles and methods and their application to the facts rather than leaving those questions entirely to the jury.
Supporting sources
May a court exclude expert testimony that rests on an analytical gap between the data and the opinion?+
Yes. When the expert's conclusions are not supported by sufficient facts or reliable methodology, the court may find too great an analytical gap and exclude the testimony. This determination is reviewed for abuse of discretion on appeal.
Supporting sources
EvidenceRelevancy and reasons for excluding relevant evidence · Expert testimonyUBEIntermediate