Daubert vs Frye: Standards for Expert Testimony

Expert witness testimony can make or break a case, but before a jury ever hears an expert’s opinion, the court must decide if that testimony is admissible. For decades, courts have relied on two primary frameworks to evaluate expert evidence: the Frye standard and the Daubert standard. 

Understanding how these standards operate — and how recent procedural updates impact them — is essential for teams preparing complex technical and scientific evidence.

In this guide, we’ll explore Daubert vs. Frye: what these standards are, how they differ, and how they’re impacted by the 2023 amendment to Rule 702.

What is the Daubert standard?

The Daubert standard is the legal framework used by federal courts and a majority of state jurisdictions to determine whether expert witness testimony is admissible at trial. Established by the U.S. Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993), it positions the trial judge as a "gatekeeper," who actively assesses whether an expert's underlying scientific principles and methodology are reliable and relevant to the facts of the case. 

The shift to Daubert was meant to solve a deep vulnerability in the court system: juries being asked to weigh complex "junk science" that even experts couldn't agree on. Years before he authored the Daubert decision, Justice Harry Blackmun famously questioned "how juries are to separate valid from invalid expert opinions when the 'experts' themselves are so obviously unable to do so.”

Daubert standards for assessing expert witnesses

The following factors are a flexible, non-exhaustive guide, rather than a checklist. The expert and their testimony don’t need to satisfy each one:

• Testability and falsifiability: The theory or technique used by the expert can be — and has been — tested using sound empirical research and objective testing methods.
• Peer review and publication: The underlying theory or methodology has been subjected to peer review and published in reputable scientific or professional journals.
• Known or potential error rate: The technique or method has a known or calculable error rate.
• Maintenance of standards: The scientific process includes rigorous operational controls and protocols that were properly maintained during the expert's evaluation.
• General acceptance: The methodology enjoys widespread acceptance within the relevant scientific or technical community, serving as a supporting factor alongside reliability.

Two later Supreme Court decisions shaped how these factors work in practice. In General Electric Co. v. Joiner (1997), the Court gave trial judges broad discretion over admissibility and held that an expert’s conclusion must actually follow from the data. A court can exclude testimony when there’s “too great an analytical gap” between the two. 

Then, in Kumho Tire Co. v. Carmichael (1999), the Court extended the gatekeeping duty to all expert testimony, not just scientific – including technical and experience-based expertise like engineering or digital forensics. Judges can apply whichever factors fit the expertise in question.

What is a Daubert motion?

A Daubert motion is a pretrial motion filed to exclude the testimony of an opposing expert witness. A team files this motion arguing that the expert’s methodology, qualifications, or conclusions fail to meet the standards set by Rule 702 (below) and Daubert.

Under Rule 702, the party offering the expert must show the court it’s more likely than not that:

• The expert is qualified by knowledge, skill, experience, training, or education
• The testimony will help the jury understand the evidence or decide a fact in issue
• The testimony rests on sufficient facts or data
• The testimony comes from reliable principles and methods
• The expert reliably applied those methods to the facts of the case

Daubert motions are typically filed after expert reports and depositions, often alongside summary judgment briefing. The court may hold an evidentiary hearing, but many motions are decided on the written briefs alone. If the motion succeeds, the judge can exclude all or part of the expert’s testimony. 

Studies have found expert testimony is excluded in whole or in part in about half (45% to 50%) of the cases where a Daubert motion is filed. This can severely weaken the opposing party's case and can force a favorable settlement or dismissal before the trial begins.

The 2023 amendment to Rule 702

In December 2023, Federal Rule of Evidence 702 was amended to clarify the judge’s gatekeeping role. Some courts had treated questions about an expert’s factual basis, or how they applied their methodology, as matters of “weight” for the jury instead of admissibility. The amendment makes clear that the party offering the expert must show the court, by a preponderance of the evidence, that each Rule 702 requirement is met. It also emphasizes that an expert’s opinion must stay within what their methodology can reliably support.

For teams using complex data or novel technology, that means the battle over admissibility shifts into early motion practice, where they must validate their methodology upfront.

What is the Frye standard?

The Frye standard was established by the Federal Court of Appeals case Frye v. United States (1923), which evaluated the admissibility of an early form of polygraph test. Under Frye, testimony is only admissible if the underlying scientific method or principle has gained general acceptance within its specific field.

Unlike Daubert, where judges evaluate scientific validity themselves, Frye leans on the scientific community to gauge reliability. If a consensus of experts in a given field accepts the methodology, the court generally admits the testimony.

Critics argue that this "general acceptance" test creates a lag when evaluating cutting-edge technology, but proponents appreciate its predictability. They prefer the reliance on domain experts over judicial interpretation.

Examples of Daubert and Frye in practice

Applying these standards in court reveals stark differences in how judges handle emerging technology, forensic analysis, and novel scientific theories across different state and federal jurisdictions.

DNA profiling and probabilistic genotyping

Probabilistic genotyping software analyzes complex DNA mixtures that older methods couldn’t reliably interpret, and it has been tested under both standards. In United States v. Gissantaner (6th Cir. 2021), a federal district court held a lengthy Daubert hearing and excluded results from the STRmix software, citing concerns about the lab’s internal validation. The Sixth Circuit reversed. It found the software testable, supported by more than 50 peer-reviewed studies, and low in error rate.

Frye courts reached a similar result by a different route. In People v. Wakefield (2022), New York’s highest court upheld the admission of results from TrueAllele, a competing program. The trial court had found after a Frye hearing that TrueAllele’s approach was generally accepted in the scientific community. The court also rejected the defense’s request for the software’s source code.

Digital forensics and electronic metadata

Location evidence from cell phone records shows how courts separate reliable technical analysis from guesswork. In United States v. Evans (N.D. Ill. 2012), a federal court applied Daubert and excluded an FBI agent’s testimony that a phone’s calls could be traced to a specific building. His estimate of each tower’s coverage range rested on training and experience, not scientific calculation. The court still allowed testimony about the underlying call records.

State courts navigate similar boundaries, though threshold limits and foundational rules often drive the outcome. In Pennsylvania, Commonwealth v. Nevels (Pa. Super. Ct. 2019) upheld the admission of historical cell-site analysis after a Frye hearing, finding the method was not novel science. The New Jersey Supreme Court, by contrast, excluded an agent’s “rule of thumb” estimate of a tower’s coverage area in State v. Burney under the state's “net opinion” rule because it lacked empirical, site-specific support. Whatever the standard, how the analyst reached the conclusion can matter as much as the data itself.

Expert admissibility standards govern evidence presented at trial, not every step of discovery. In Da Silva Moore v. Publicis Groupe (S.D.N.Y. 2012), the court held that Rule 702 and Daubert don’t apply to discovery-stage methods like technology-assisted review. Whether a document is admissible depends on the document itself, not how it was found. Still, documenting a defensible, transparent review process helps when methodology is challenged at any stage.

Toxic torts and causation science

Mass tort cases often turn on whether experts can reliably connect an exposure to an illness. In In re Acetaminophen – ASD-ADHD Products Liability Litigation, the federal district court applied the newly amended Rule 702 to exclude all five of the plaintiffs’ general causation experts and granted summary judgment to the defense. In Rutledge v. Walgreen Co. (2026), the Second Circuit vacated that judgment. It held that the district court exceeded its discretion in excluding three experts whose methods matched those used by other scientists in their fields, and it upheld the exclusion of the other two. Disagreements over how those three experts weighed the science, the court said, were for the jury to decide. The Second Circuit later denied the defendants’ petition for rehearing. (Note: This case is still active; this update is current as of October 27, 2026.)

Frye jurisdictions also require a reliable scientific link. In Parker v. Mobil Oil Corp. (2006), a gas station attendant alleged that benzene exposure caused his leukemia. New York’s highest court rejected his experts’ causation opinions because they didn’t connect his level of exposure to the disease. The court noted that exposure doesn’t need to be measured with mathematical precision, but the expert’s conclusion must still rest on reliable science.

Engineering and technical analysis

Daubert’s gatekeeping role isn’t limited to laboratory science. Kumho Tire Co. v. Carmichael (1999) began after a minivan tire blew out. The plaintiffs’ tire-failure expert relied on a visual and tactile inspection method to conclude the tire was defective. The Supreme Court upheld the trial court’s exclusion of that testimony. It held that the judge’s gatekeeping duty applies to all expert testimony, including engineering and other technical or experience-based expertise. Courts can apply whichever Daubert factors fit the type of expertise.

Frye jurisdictions often take a narrower view. Frye generally applies to novel scientific techniques, so many Frye courts, including New York’s, have held that an engineer’s opinion based on training and experience doesn’t require a Frye hearing at all. In those courts, challenges to the expert’s reasoning are typically left for cross-examination and the jury.

How are the Frye and Daubert standards similar?

While the legal tests differ in their approach, both the Frye standard and the Daubert standard aim to keep unreliable or pseudoscientific evidence away from juries. Here is a high-level comparison of the Frye standard vs Daubert standard.

Shared focus on filtering junk science

Both standards exist to prevent juries from being misled by unsupported theories or unreliable expertise. Whether evaluating a lie detector in 1923 or complex machine learning algorithms today, both legal tests serve as essential filters to preserve the integrity of judicial proceedings.

Requirement for expert qualification

Under both Frye and Daubert, the witness must first qualify as an expert through sufficient knowledge, skill, experience, training, or education. No methodology — regardless of its general acceptance or scientific rigor — can be admitted through an unqualified witness.

Emphasis on relevance to the dispute

Neither standard allows expert testimony simply because it’s scientifically sound. The expert's insights must help the court make sense of complex facts or decide a central issue. If scientific data does not fit the specific legal question, it is excluded under both rules.

Dependence on pretrial motion practice

In both state and federal courts, challenges under either standard are typically raised through pretrial motions. Teams use these proceedings to present competing evidence and resolve evidentiary disputes well before opening statements begin.

Evaluation of foundational scientific principles

Both frameworks look beyond the expert’s credentials, focusing instead on the underlying science. Even in Frye jurisdictions, courts must verify the foundational discipline is recognized. Experts may not offer personal conjecture that isn’t supported by professional norms.

How do the Frye and Daubert standards differ?

When looking at the Frye standard vs Daubert standard, the operational distinction is this: Who has the authority to validate scientific procedures?

Judicial gatekeeping versus expert consensus

The most significant difference lies in who evaluates scientific validity. Frye relies on external consensus, requiring judges to defer to what most scientists in a field think. Daubert empowers judges to independently evaluate the scientific validity of the methods used, making the court an active arbiter of reliability.

Treatment of novel scientific techniques

Frye can create hurdles for cutting-edge techniques. New technology may not be admitted if it doesn’t have enough of a track record or widespread community adoption. Daubert offers a more flexible structure for novel methods, allowing teams to introduce emerging science if they can demonstrate sound testing, peer review, and known error rates.

Scope of evaluation factors

Frye focuses on a single question: Is the technique generally accepted? Daubert gives courts multiple ways to assess reliability. By looking at testability, peer review, error rates, operational standards, and general acceptance, it tends to be more flexible. 

Application of Federal Rule 702

Federal Rule 702 governs only federal courts. State courts follow their own evidence rules. Some Frye states have a state Rule 702 that incorporates the general acceptance test, while others rely on case law.

Burden on procedural methodology

Under the Daubert rule, misapplying a valid method can get an expert’s testimony thrown out before trial. 

Frye’s general-acceptance test focuses on the method, though some Frye courts (like New York) separately scrutinize whether the expert’s conclusions are supported.

Which standard does your state follow?

All federal courts and a clear majority of states follow Daubert or a Daubert-based standard. A smaller group — including California, New York, Pennsylvania, and Illinois — follows Frye, and roughly a dozen states use their own hybrid tests.

Because evidentiary rules vary by forum, teams operating across multiple jurisdictions must tailor their preparation, data collection, and evidentiary motions to the standard governing the trial court.

You can check your state’s status here (current as of 2023).

How DISCO keeps your methodology transparent and reliable

Whether navigating a Daubert challenge in federal court or meeting the Frye standard in state litigation, the key to surviving expert scrutiny is complete transparency into how data was handled, searched, and analyzed. A strong legal argument requires an uninterrupted chain of custody and verifiable processes from initial collection through trial presentation.

DISCO provides cloud-native solutions that ensure your technical evidence stands up to intense judicial gatekeeping. By partnering with DISCO Forensic Services & Collections for sound data gathering and leveraging the advanced search and review capabilities of the DISCO Platform, teams can ensure every piece of digital evidence is backed by reliable, repeatable methodologies.

Ready to streamline your ediscovery and strengthen your evidentiary foundation? Schedule a demo today to see how DISCO is with you in every case.