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AugMore than a century after it was decided, Frye v. United States still determines whether expert testimony reaches a jury in some of the busiest litigation venues in the country.
Attorneys tend to think of admissibility standards as background law. In practice, the standard governing your jurisdiction shapes expert selection, methodology, and case strategy from day one. An expert who would sail through a Daubert hearing in federal court can be excluded under Frye in state court and by the time that happens, it is usually too late to recover.
Here is what the Frye standard is, where it came from, how it differs from Daubert, and what it means for how you select and prepare experts.
The Frye standard sometimes called the “general acceptance test” holds that expert testimony based on a scientific technique is admissible only if that technique is generally accepted as reliable in the relevant scientific community.
The question under Frye is not whether the expert is qualified or whether the reasoning seems sound to the judge. The question is narrower: has the methodology gained standing among the specialists in that field? If the method is still experimental, contested, or novel, the testimony stays out no matter how credentialed the witness.
That single test governed expert admissibility in American courtrooms for seventy years, and it still governs it in several major states today.
In 1920, James Alphonso Frye was charged with second-degree murder. His defense sought to introduce results from a “systolic blood pressure deception test” an early precursor to the modern polygraph arguing the results showed Frye was truthful when he denied the crime.
The D.C. Circuit Court of Appeals refused to admit the testimony. The court reasoned that a scientific principle must cross the line from the experimental to the demonstrable before courts will accept expert testimony built on it, and the deception test had not yet earned recognition among physiological and psychological authorities.
Frye was convicted. But the two-page opinion outlived the verdict. Courts adopted its “general acceptance” reasoning as the governing test for scientific evidence, and for most of the twentieth century, Frye was the law of expert testimony nearly everywhere.
In Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993), the U.S. Supreme Court held that the Federal Rules of Evidence not Frye govern admissibility in federal court. The decision replaced the single general-acceptance question with a flexible reliability inquiry, with the trial judge acting as “gatekeeper.”
The practical differences matter:
Neither standard is uniformly “easier.” A well-established methodology applied loosely may survive Frye but fail Daubert standard. A newer, rigorously validated method may survive Daubert but fail Frye. The standard changes what your expert must be prepared to defend.
Federal practice has also kept moving: a December 2023 amendment to Federal Rule of Evidence 702 clarified that the proponent must establish each admissibility requirement by a preponderance of the evidence a reminder that courts are tightening, not loosening, their scrutiny of expert opinions.
All federal courts follow Daubert, and a majority of states have adopted Daubert or a close variant. But several significant jurisdictions still apply Frye or a Frye-based test, including New York, Illinois, Pennsylvania, Washington, and Minnesota, with California applying its own general-acceptance variant to novel scientific techniques. The differences in these standards are covered in Frye vs. Daubert by state. A number of other states apply hybrid approaches that borrow from both.
Two cautions. First, this landscape keeps shifting states have continued to migrate toward Daubert in recent years, and some apply different tests to different types of evidence. Second, even among Frye states, application varies: what “general acceptance” requires in a New York courtroom is not identical to Pennsylvania practice. Always confirm the current governing standard in your venue before committing to an expert strategy, and partner with comprehensive expert witness services that make sure your expert knows which test their opinion must survive.
A Frye challenge typically arrives as a motion to preclude, often resolved at a pretrial hearing. The dispute is rarely about the expert’s CV. It is about the method underneath the opinion.
The opposing side will argue that the technique is novel, that the supporting literature is thin, or that the expert has stretched an accepted method into territory the field has not endorsed. That last argument is the most common trap: an expert using a mainstream methodology can still be excluded if the application say, extrapolating causation at exposure levels the literature does not address lacks general acceptance.
Surviving the challenge comes down to preparation done months earlier:
Frye v. United States is significant not for its outcome but for the discipline it imposed: courts demand that expert opinions rest on methods the relevant field actually trusts. A century later, that demand in Frye form or Daubert form is the first hurdle every expert opinion must clear.
The attorneys who clear it consistently are the ones who treat admissibility as an expert-selection question, not a motion-practice question. The right expert, matched to the right question, with a methodology and track record that hold up under scrutiny, rarely faces a challenge they cannot survive.
That is where we come in. At Homestead, every expert we place is vetted for credentials, methodology, and prior challenge history before introduction so the expert you retain is one whose opinion can withstand Frye or Daubert scrutiny. Submit a case and speak with a matched expert before you commit.