What Is the Frye Standard?

The Frye standard is the test New York courts use to decide whether expert testimony based on scientific principles can be admitted at trial. A scientific method or technique passes the Frye standard only if it has gained "general acceptance" in the relevant scientific community. New York still applies Frye today. Federal courts do not. They use the broader Daubert standard instead.

If you have a personal injury, medical malpractice, or toxic exposure case in New York, this is not an abstract legal footnote. Expert testimony is often the evidence your entire case turns on. That might be a doctor explaining how a medical error caused your injury, an engineer describing a construction defect, or a toxicologist linking a chemical exposure to your illness. If a judge decides the method behind that testimony does not meet the Frye standard, the testimony can be thrown out. Your claim can collapse with it. This is why your attorney's choice of expert, and the methods that expert relies on, can decide a case.

This article explains where the Frye standard came from and how New York courts apply it today. It also covers when a Frye hearing is actually required, how Frye differs from the federal Daubert standard, and what all of it means for your case.

The Origins: Where Did the Frye Standard Come From?

The Frye standard comes from a 1923 federal case, Frye v. United States, decided by the Court of Appeals for the District of Columbia. A defendant wanted to introduce the results of an early lie detector test to prove his innocence. The test was a "systolic blood pressure deception test." The court refused to allow it.

In its short opinion, the court set out the rule that would carry its name for the next century. Expert testimony drawn from a scientific principle is admissible only once that principle has moved past the experimental stage. As the court put it, the thing the expert bases a conclusion on "must be sufficiently established to have gained general acceptance in the particular field in which it belongs." (Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).)

That single phrase, "general acceptance," became the entire test. The decision came 50 years before the Federal Rules of Evidence. Over time most federal courts moved away from Frye, but New York did not. The state still relies on the general acceptance test that Frye set out more than a hundred years ago.

How the Frye Standard Works in New York Courts Today

New York courts have refined the Frye standard into a two-step analysis. The New York Court of Appeals laid it out most clearly in Parker v. Mobil Oil Corp., 7 N.Y.3d 434 (2006). Understanding both steps is the key to understanding why some expert testimony gets in and some does not.

Step one is the Frye inquiry. The court asks whether the method the expert relied on is generally accepted as reliable within the relevant scientific community. This is a question about the methodology in general. It is not about the particular expert or the particular case.

Step two is the foundational inquiry. Even when a method clears the Frye step, the court separately asks whether the accepted method was properly applied to the facts of this specific case. As Parker makes clear, this is a different question from general acceptance. An expert can use a generally accepted method and still have their testimony excluded. That happens if the factual foundation for the opinion is weak. The data, the assumptions, or the way the method was carried out may be inadequate. (Parker v. Mobil Oil Corp., 7 N.Y.3d 434 (2006).)

These two inquiries are easy to blur together, but they are not the same. The Frye standard is about whether the science is sound in the abstract. The foundational step is about whether the expert applied that sound science correctly to your situation.

A few practical points follow from this framework.

"General acceptance" does not mean unanimous agreement. New York case law describes general acceptance as something widespread, prevalent, and extensive, though not necessarily universal. It is enough that a substantial section of the relevant scientific community accepts the method. A handful of dissenters does not defeat general acceptance. A single enthusiastic expert does not establish it.

The party offering the testimony bears the burden. If you are the one who wants the expert's testimony admitted, your side has to show that the underlying method is generally accepted. This is one reason the choice of expert matters so much. Your attorney needs an expert who relies on methods that can actually carry that burden.

A court does not need a hearing to find general acceptance. General acceptance can be shown in several ways. The court can take judicial notice of it. It can rely on legal and scientific writings, or on prior judicial opinions that already recognized the method. Or it can hold a dedicated Frye hearing. New York's official evidence rules on expert opinion testimony reflect this practice. (NY Courts Guide to Evidence, Rule 7.01, Opinion of Expert Witness.) A hearing is only one of several routes. That leads directly to a point many explanations of Frye get wrong.

When Is a Frye Hearing Actually Required?

A Frye hearing is not automatic. It is not held every time an expert takes the stand. This is the single most misunderstood part of the standard, so it is worth stating plainly. A Frye hearing is required only when the underlying scientific theory or technique is novel or experimental.

If an expert relies on an established, widely accepted method, no Frye hearing is needed. The court can recognize the method's general acceptance through case law or judicial notice and move on. The Frye gate exists to screen out unproven or fringe science. It is not meant to relitigate methods the scientific community settled long ago.

There is a related and equally important limit. The Frye rule is about scientific methodology, not about an expert's professional judgment. An expert may offer an opinion grounded in their own training, clinical experience, and skill within an accepted field. That kind of opinion generally does not trigger Frye at all. A New York appellate decision in 2024 illustrated this distinction. In Ghazala v. Shore Haven Apartment Del, LLC, the Second Department held that an expert engineer's testimony based on personal training and experience did not require a Frye hearing. A Frye hearing is not triggered just because the other side disagrees with the conclusion. (Ghazala v. Shore Haven Apartment Del, LLC, 2024 NY Slip Op 03681 (2d Dep't 2024).)

In practice, here is how it tends to play out. Either party can ask the court for a Frye hearing, usually before trial through a motion challenging the other side's expert. The court decides whether the challenged method is novel enough to warrant a hearing. If it is, the parties present evidence. That often means competing experts, scientific literature, and prior rulings. The judge then decides whether the method has earned general acceptance. If the method is well established, the court can deny the request for a hearing and let the testimony move to the foundational analysis.

Some examples make the line clearer. A judge would likely order a Frye hearing if a plaintiff's expert proposed to use a brand-new diagnostic technique that no court had ever evaluated. A judge would likely not order one for a physician diagnosing a fracture from a standard X-ray, because that method is beyond dispute. The question is always whether the science is novel, not whether the expert's opinion helps one side.

Frye vs. Daubert: Why the Difference Matters for New York Cases

Most people who research expert testimony quickly run into a second name: Daubert. The Daubert standard comes from a 1993 U.S. Supreme Court decision, Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579. It governs federal courts and the majority of states. New York is one of the states that kept Frye instead. The Frye vs. Daubert distinction in New York matters because the two tests can reach different results on the same evidence.

The core difference is the judge's role. Under the Frye standard, the judge plays a limited gatekeeping role. The judge essentially asks the scientific community a single question: does your field accept this method? Under Daubert, the judge becomes an active gatekeeper. The judge evaluates the reliability of the methodology directly, using a multi-factor analysis.

Here is how the two standards compare:

The practical effect is that the Frye standard can be harder on new science. A method that is reliable but too new to have won broad acceptance may struggle under Frye. The same method could be admitted under Daubert. Diffusion tensor imaging (DTI) is a good example. DTI is a brain scan used to detect traumatic brain injury. New York state courts found DTI admissible under Frye as early as 2018, when a court held that the plaintiff had presented sufficient evidence of general acceptance through peer-reviewed publications and medical affirmations. DTI now passes Frye in New York. A method like that might have been admitted earlier in a Daubert jurisdiction, before general acceptance had fully taken hold.

There is also a hybrid reality worth understanding. New York formally applies Frye. Still, trial judges increasingly fold reliability-style considerations into their analysis. They informally weigh factors that look a lot like the Daubert checklist, even while the governing test remains general acceptance. The two standards are converging more in practice than the formal labels suggest.

One more point surprises many New Yorkers. If your case is filed in federal court in New York, Daubert applies, not Frye. That covers the Southern District (SDNY) and the Eastern District (EDNY). The standard that governs your expert depends on which courthouse your case is in.

What Types of Expert Testimony Does the Frye Standard Affect in NYC Personal Injury Cases?

The Frye standard reaches into nearly every category of personal injury and malpractice litigation that depends on scientific or technical proof. Here are a few of the most common scenarios in New York City cases.

Medical experts in malpractice cases. A physician may testify about the standard of care, a diagnosis, or whether a doctor's error caused harm. The methods behind those opinions can be challenged. Causation testimony in particular is a frequent target. That is the link between an alleged error and a specific injury.

Accident reconstruction and biomechanical experts. In a car or truck accident case, experts may use biomechanical analysis to explain how a crash produced a particular injury. New York courts have both allowed and excluded biomechanical causation testimony, depending on the method used. That shows Frye analysis is method-specific, not category-specific. The fact that one biomechanical expert was excluded does not mean all of them will be.

Toxicologists in exposure cases. Linking a chemical exposure to an illness is one of the hardest things to prove, and it is squarely a Frye issue. Parker v. Mobil Oil Corp. itself involved exactly this. The Court of Appeals upheld the exclusion of expert opinions that tried to link benzene exposure to the plaintiff's leukemia. The experts had not adequately shown the causal connection under a generally accepted methodology.

Forensic experts in criminal cases. The Frye standard still does active work in criminal court. In 2026, a New York judge ordered a Frye hearing on ballistics testimony involving microscopic comparison of shell casings. That is a reminder that even long-used forensic techniques can face fresh scrutiny under the general acceptance test.

Engineering experts in construction and premises cases. Engineers may testify about construction defects, code violations, or unsafe conditions, and they can face Frye challenges. As noted above, though, opinions resting on accepted engineering methods and professional experience often do not require a hearing.

It is just as important to know what Frye does not reach. It does not bar an expert from offering clinical judgment based on accepted training and experience. It does not apply to ordinary lay opinion. The dividing line, again, is whether the testimony depends on a novel scientific method.

How the Frye Standard Affects Your Personal Injury or Malpractice Case

For an injured person, the Frye standard is easiest to understand by its consequence. If your expert's testimony is excluded under Frye, the part of your case that testimony was meant to prove may have no support left. That part is often causation or the standard of care. Losing it can weaken your case badly or end it entirely. Defense attorneys know this. That is why a Frye challenge is a common strategic move. Knocking out a plaintiff's key expert before the jury ever hears from them can be as decisive as winning at trial.

This is why the work happens long before any hearing. An experienced attorney evaluates the expert's methods before retaining the expert. The attorney asks whether those methods are novel or well established, and whether they can withstand a Frye challenge. The goal is to build the case on accepted methodology from the start. Where a Frye hearing is likely, the attorney prepares for it. The aim is to be ready to show general acceptance through case law and literature, rather than leaving it to chance.

A forward-looking frontier is also emerging. The New York court system's Advisory Committee on Artificial Intelligence and the Courts released its 2025 annual report. It recommended examining whether the Frye standard should be modified to account for AI-generated evidence. Frye poses a particular puzzle for AI. The test depends on identifying a "relevant scientific community" that accepts a method. For AI forensic tools, that community is often ill-defined, and professional standards tend to lag well behind the technology. As AI tools work their way into evidence, expect the limits of the general acceptance test to be tested in new ways.

Frequently Asked Questions

What is the Frye standard in simple terms?

The Frye standard is a rule for deciding whether expert testimony based on science can be used in court. The science behind the testimony must be generally accepted as reliable by experts in that field. If it is too new, fringe, or unproven, the judge can keep it out. New York has applied this general acceptance test since 1923.

Does New York use the Frye or Daubert standard?

New York uses the Frye standard. Federal courts and most other states use the Daubert standard. So a state-court case in New York is governed by Frye. A case in a New York federal court, the Southern or Eastern District, is governed by Daubert.

When is a Frye hearing required in New York?

A Frye hearing is required only when the scientific theory or technique behind the expert's testimony is novel or experimental. If the method is already well established and accepted, no hearing is needed. The court can recognize its acceptance through prior case law or judicial notice.

What does "generally accepted" mean under the Frye standard?

Under the Frye standard, "generally accepted" means the method is widely accepted within the relevant scientific community. New York case law describes this as widespread, prevalent, and extensive, though not necessarily universal. Acceptance by a substantial section of the field is enough. Unanimous agreement is not required.

Who bears the burden of proof in a Frye hearing?

The party offering the expert testimony bears the burden of showing that the underlying method is generally accepted under the Frye standard. If you want your expert's testimony admitted, your side must demonstrate the method's acceptance to the court's satisfaction before the jury ever hears from that expert.

What happens if an expert fails the Frye standard?

If an expert's method fails the Frye standard, the court excludes that testimony. The jury never hears it. Expert testimony often supplies the proof of causation or the standard of care, so an exclusion can seriously weaken or even end a case.

How is the Frye standard different from the Daubert standard?

Under the Frye standard, the judge asks a narrow question: does the scientific field accept this method? Under Daubert, the judge actively evaluates the method's reliability, using factors such as testing, peer review, error rate, and acceptance. Daubert is generally more open to newer science.

Does Frye apply in federal court cases filed in New York?

No. Cases in New York's federal courts — the Southern District (SDNY) and Eastern District (EDNY) — follow the federal Daubert standard, not Frye. The Frye standard applies only in New York state courts. Which courthouse your case is filed in determines which test your expert must satisfy.

Can a judge exclude expert testimony even if it passes Frye?

Yes. New York applies a two-step analysis. Even after a method clears the Frye general-acceptance step, the judge separately asks whether the method was properly applied to the facts of the specific case. A weak factual foundation can lead to exclusion despite passing Frye.

How does the Frye standard affect medical malpractice cases in New York?

Medical malpractice cases lean heavily on expert testimony about the standard of care, diagnosis, and causation. Defense attorneys often use Frye challenges to attack the methods behind a plaintiff's causation experts. If that testimony is excluded under the Frye standard, proving the doctor's error caused the injury becomes far harder.

Sources & Official Resources

Cases Cited

1. Frye v. United States, 293 F. 1013 (D.C. Cir. 1923) — U.S. Courts (Second Circuit program materials)
2. Parker v. Mobil Oil Corp., 7 N.Y.3d 434 (2006) — NY Court of Appeals via nycourts.gov
3. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) — U.S. Supreme Court via supremecourt.gov
4. Ghazala v. Shore Haven Apartment Del, LLC, 2024 NY Slip Op 03681 — NY Appellate Division, Second Department via nycourts.gov

New York Evidence Rules 5. NY Courts Guide to Evidence, Rule 7.01 — Opinion of Expert Witness

Helpful Resources 6. NY Courts Advisory Committee on Artificial Intelligence and the Courts — Annual Report 2025

Contact The Orlow Firm

If you were injured in New York City and your case depends on expert testimony, whether that testimony is admitted under the Frye standard can decide whether you recover anything at all. Your case might turn on a doctor explaining a medical error, an engineer describing a construction defect, or a toxicologist connecting an exposure to your illness. The Orlow Firm has handled personal injury and medical malpractice cases throughout New York for over 40 years, with offices in Queens, Manhattan, Brooklyn, and the Bronx.

Call (646) 647-3398 for a free consultation. We work on contingency — you pay nothing unless we win.

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This article provides general information and is not legal advice. Every case is different. Contact an attorney to discuss your specific situation.