The difference between the Frye and Daubert standards comes down to who decides whether an expert’s method is reliable enough for a jury to hear. Frye, from a 1923 federal case, asks only whether the technique is generally accepted in its scientific field. Daubert, decided by the U.S. Supreme Court in 1993, puts the trial judge in a gatekeeping role and requires an independent look at scientific validity, methodology, and relevance. Most federal and state courts now follow some version of Daubert; a handful of states still apply Frye.
What the Frye Standard Asks
Frye comes from Frye v. United States, a 1923 case in which the defendant tried to introduce results from an early blood-pressure-based lie detector test. The court excluded the evidence and set the rule that a scientific technique must be “sufficiently established to have gained general acceptance in the particular field in which it belongs” before a court can admit testimony based on it.1Justia. Frye v. United States
The judge’s inquiry under Frye is narrow. The question is not whether the judge personally finds the methodology sound, but whether the broader scientific community treats it as reliable. If the technique is well-established and accepted by peers in the field, it comes in. If it’s too new or too controversial to have earned that consensus, it stays out. Frye is conservative by design: cutting-edge science tends to be excluded until the relevant field catches up.
What the Daubert Standard Asks
In 1993, the Supreme Court replaced Frye as the federal standard in Daubert v. Merrell Dow Pharmaceuticals, Inc., a case brought by parents who claimed the drug Bendectin caused birth defects. The Court held that the Federal Rules of Evidence, not Frye’s general acceptance test, govern the admissibility of expert testimony in federal trials.2Justia U.S. Supreme Court Center. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) Rule 702, which addresses expert testimony, contains nothing that requires general acceptance as a precondition for admissibility.
Instead of deferring to scientific consensus, Daubert puts the trial judge in a “gatekeeping” role. The judge must independently assess whether the expert’s reasoning and methodology are scientifically valid and whether the testimony is relevant to the facts of the case. The Court emphasized that this inquiry should focus on the expert’s principles and methods, not on the conclusions those methods produce.2Justia U.S. Supreme Court Center. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)
The Daubert Factors
The Court outlined several factors a judge can weigh when evaluating reliability. These are guidelines, not a rigid checklist:
- Whether the theory or technique can be tested, and has been tested.
- Whether the work has been published in peer-reviewed journals or otherwise subjected to scrutiny by other experts.
- The known or potential rate of error, along with the existence of standards governing how the technique is applied.
- Whether the method is generally accepted in the relevant scientific community. This factor survived from Frye, but under Daubert it is one consideration among several rather than the only test.2Justia U.S. Supreme Court Center. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)
No single factor is decisive. A technique with a high error rate might still be admissible if it has been extensively peer-reviewed and tested. General acceptance alone will not save testimony built on flawed methodology. The judge weighs the totality of the factors as they apply to the specific case.
Later Supreme Court decisions extended Daubert. General Electric Co. v. Joiner (1997) held that appellate courts review a trial judge’s admissibility ruling only for abuse of discretion, giving trial judges wide latitude.3Justia U.S. Supreme Court Center. General Electric Co. v. Joiner, 522 U.S. 136 (1997) Kumho Tire Co. v. Carmichael (1999) confirmed that the gatekeeping role applies to all expert testimony, not just scientific testimony — engineers, accountants, and other specialists are subject to the same analysis, though the judge has flexibility to decide which factors fit the particular expertise.4Justia U.S. Supreme Court Center. Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999)
The Core Differences in Practice
The most fundamental difference is who decides reliability. Under Frye, the scientific community effectively makes the call through its consensus. Under Daubert, the judge makes an independent determination using multiple criteria. That gives Daubert judges considerably more power over what the jury hears, and it demands more of them. A Frye hearing can be relatively straightforward: does the field accept this method or not? A Daubert hearing often involves a deeper look at how the expert conducted the analysis, what data was used, and whether the methodology was properly applied to the facts.
Daubert is generally more flexible than Frye toward newer science. A technique that has not yet gained widespread acceptance may still be admissible under Daubert if the expert can demonstrate sound testing, a low error rate, and peer scrutiny. Under Frye, the same evidence would likely be excluded until the field reached consensus. The practical stakes are highest in toxic tort cases, product liability suits, and patent disputes, where the ability to introduce emerging scientific methods can decide the outcome.
Daubert also cuts the other way. It can be used to exclude evidence that would pass Frye. If an expert relies on a generally accepted methodology but applies it sloppily to the specific facts, a Daubert judge can keep the testimony out. Under Frye, the court’s inquiry typically ends once general acceptance is established, leaving application issues for cross-examination rather than exclusion.
Where Each Standard Applies Today
All federal courts apply Daubert. Federal Rule of Evidence 702 was amended effective December 1, 2023, to clarify the judge’s gatekeeping burden. The updated rule states that an expert may testify only if “the proponent demonstrates to the court that it is more likely than not” that the testimony meets each admissibility requirement: that the expert’s knowledge will help the jury, the testimony rests on sufficient facts or data, it is the product of reliable methods, and the expert reliably applied those methods to the case.5Legal Information Institute. Rule 702 – Testimony by Expert Witnesses
The amendment responded to a pattern in some courts. Judges had been treating questions about the sufficiency of an expert’s data and the reliability of the expert’s application of methodology as issues of “weight” for the jury rather than threshold admissibility questions. The amended rule makes clear these are gatekeeping determinations the judge must resolve before the testimony reaches the jury. If an expert’s factual basis is inadequate, the opinion is inadmissible.
Most states have also adopted some version of Daubert, either through court decisions or by amending their state evidence rules to mirror Rule 702. A smaller group still follows the Frye general acceptance test; California, Illinois, Minnesota, New York, Pennsylvania, and Washington are among the most prominent Frye jurisdictions. Some states apply hybrid approaches, treating general acceptance as a significant factor within a broader reliability analysis. Because states periodically change course through court decisions or legislation, it’s worth confirming which standard applies in a given jurisdiction before trial.
The consequence is that the same expert testimony can be admissible in one courtroom and excluded in another. An opinion based on a newer methodology that passes Daubert’s flexible test may be blocked in a Frye state where the technique lacks broad acceptance. Attorneys in multi-state litigation need to account for this when preparing expert witnesses.
How a Challenge Actually Works
The usual way to challenge expert testimony is through a pretrial motion in limine, filed before trial begins. The motion asks the judge to rule on admissibility before the jury ever hears the expert. When the challenge is based on Daubert, the judge usually holds a hearing, commonly called a Daubert hearing, where both sides argue over the expert’s qualifications, methodology, data, and conclusions.
At a Daubert hearing, the challenger argues that the testimony fails one or more reliability requirements. The proponent responds by showing that the methodology is testable, peer-reviewed, has a manageable error rate, and is accepted within the field. The judge may examine the expert’s reports, deposition testimony, and underlying data, then admit the testimony, exclude it entirely, or limit its scope.
Under Frye, the challenge is narrower. The opposing party argues that the technique has not achieved general acceptance, and the proponent offers evidence of consensus in the scientific community, typically through publications, professional standards, or testimony from other practitioners. Because the inquiry is more focused, Frye hearings tend to be shorter and less complex than Daubert hearings.
Whichever standard applies, the stakes are high. Excluding a key expert can effectively end a case, especially in areas like medical malpractice or product liability where expert testimony is required to establish causation.