The Frye Standard

A 1923 murder appeal, and the two pages it produced

Frye v. United States, 293 F. 1013, was decided on 3 December 1923 by the Court of Appeals of the District of Columbia — an intermediate federal appellate court and the predecessor of today’s D.C. Circuit. The modern citation form, “D.C. Cir. 1923,” is shorthand for a court that was not then styled that way. It is not a decision of the Supreme Court of the United States, which has never adopted the test and which, the one time it addressed the question squarely, held the test inapplicable in federal court.

James Alphonso Frye had been convicted of second-degree murder. The defense offered the results of a systolic blood pressure deception test — an ancestor of the polygraph rather than the polygraph itself — administered by William Moulton Marston, a Harvard-trained lawyer and psychologist. The opinion describes the premise in one sentence: “In other words, the theory seems to be that truth is spontaneous, and comes without conscious effort, while the utterance of a falsehood requires a conscious effort, which is reflected in the blood pressure.” The trial court had refused both the test results and expert testimony about them. The judgment was affirmed.

The opinion is authored, not per curiam. It carries the byline “VAN ORSDEL, Associate Justice,” and was decided by a panel of Chief Justice Smyth, Associate Justice Van Orsdel, and Presiding Judge Martin of the United States Court of Customs Appeals, sitting by designation. The mistake is common enough to be worth correcting; it probably survives because the entire opinion runs across two pages of the Federal Reporter, 293 F. 1013–1014.

The passage, and it is two sentences long

The rule that carries the case name is a single passage. Quoted whole, it reads:

“Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.” 293 F. at 1014.

Two features of that text are lost in almost every paraphrase. First, the opinion does not say “generally accepted in the scientific community.” It says “general acceptance in the particular field in which it belongs” — the relevant community is defined by the technique, and the modern fight under the test is precisely about how narrowly or broadly that field is drawn. Second, the sentence contains a clause that favors the proponent and is rarely quoted: courts “will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery.”

The application, which is the actual holding, is a separate sentence: the deception test “has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made.” Primary text: the opinion at 293 F. 1013.

The question it asks is about a community, not about a method

General acceptance is a question of fact about a field. The court is in substance taking a census: does the relevant discipline accept this technique? It is not asked to decide whether the technique works, and in the stricter formulations it is not permitted to. Pennsylvania’s Supreme Court made that limit explicit in Walsh v. BASF Corp., 234 A.3d 446 (Pa. 2020), holding that a court conducting the inquiry may not “question the merits of the expert’s scientific theories, techniques or conclusions” and abuses its discretion when it rules on its own reading of the scientific literature rather than on a review of methodology.

That is a materially different exercise from the one a federal judge performs under FRE 702, where the court must find by a preponderance that the method is reliable and that the opinion reflects a reliable application of it. One inquiry defers to a field; the other makes a determination about the science.

The counting problem is the test’s central difficulty and the source of most litigation about it. Who constitutes the “particular field”? A proponent defines it narrowly — the practitioners who use the technique, and who by definition accept it. An opponent defines it broadly — the surrounding discipline, which may not. Nothing in the federal framework produces an equivalent fight, because no federal question turns on drawing the boundary of a community.

Where general acceptance still gates novel science

Six states can be confirmed from rule text or from their own high courts as applying general acceptance to novel scientific methodology.

• Illinois — Ill. R. Evid. 702 (eff. 1 Jan. 2011) codifies the test in its second sentence and applies it only “[w]here an expert witness testifies to an opinion based on a new or novel scientific methodology or principle.” The committee comment states that the rule “confirms that Illinois is a Frye state.”
• Pennsylvania — Pa.R.E. 702(c) is the only operative rule text in the country to carry the requirement directly: admissibility requires that “the expert’s methodology is generally accepted in the relevant field.” Grady v. Frito-Lay, Inc., 839 A.2d 1038 (Pa. 2003) confines the analysis to novel science.
• Minnesota — the Frye-Mack standard, Goeb v. Tharaldson, 615 N.W.2d 800 (Minn. 2000), which expressly declined to adopt the federal approach.
• New York — common-law, uncodified, People v. Wesley, 83 N.Y.2d 417 (1994).
• Washington — Lakey v. Puget Sound Energy, Inc., 176 Wn.2d 909 (2013).
• California — as the Kelly test, People v. Kelly, 17 Cal. 3d 24 (1976), reaffirmed after 1993 in People v. Leahy, 8 Cal. 4th 587 (1994), and limited to new scientific techniques.

Published fifty-state charts add and subtract states from that list, and several are years out of date. The list above is what can be confirmed; anything beyond it should be checked against the forum’s current rule.

No state relies on general acceptance alone

The gate catches the method. It says nothing about whether this expert applied the method correctly, which in the classical formulation is a matter of weight. Every state on the list above has built a second screen to close that gap, and the second screen is where experts are more often lost.

Washington states the division most crisply. In Lakey: “Frye excludes testimony based on novel scientific methodology until a scientific consensus decides the methodology is reliable; ER 702 excludes testimony where the expert fails to adhere to that reliable methodology.” The expert in that case cleared the first step — his epidemiological methods were accepted — and was excluded under ER 702 for his handling of the data.

New York runs the same two-step through Parker v. Mobil Oil Corp., 7 N.Y.3d 434 (2006), which separates the general-acceptance question from whether “there is an appropriate foundation for the experts’ opinions.” Minnesota requires that every expert opinion have “foundational reliability” and layers general acceptance on top for novel scientific theory only. California adds the gatekeeping duty of Sargon Enterprises, Inc. v. University of Southern California, 55 Cal. 4th 747 (2012), under which a court excludes opinion that rests on material an expert may not reasonably rely on, on reasons unsupported by that material, or on speculation — a duty built out of the California Evidence Code and applying to all expert opinion. Reading “this is a Frye jurisdiction” as “the bar is low” misdescribes all four.

The experience-based expert is usually outside the gate entirely

In most general-acceptance states the trigger is novel scientific evidence, which by its terms leaves out the witness whose qualification is experience rather than a laboratory method. Illinois says so in the rule text. New York reaches novel science and tests everything else through qualification and the Parker foundation inquiry. Pennsylvania’s rule is written broadly but Grady confines the analysis to novel science. Washington screens the non-scientific expert under ER 702’s helpfulness and qualification requirements instead.

Two states are the exception. Minnesota imposes foundational reliability on every expert opinion, so the experience-based witness is gatekept there in a way most general-acceptance states do not manage. California applies Kelly only to new scientific techniques, but Sargon — itself a lost-profits case, not a science case — reaches valuation and experience-based opinion alike.

The practical consequence is worth stating flatly: against a non-scientific expert in a general-acceptance state, the general-acceptance motion is usually the wrong motion. It invites the answer that the test does not apply, which is often correct and rarely the end of the matter. The available challenges are to qualification, to the foundation of the opinion, to whether the testimony will help the trier of fact, and to the state’s analytical-support doctrine where it has one.

What became of the test in federal court

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), held that the Federal Rules of Evidence, not Frye, supply the standard in a federal trial. The reasoning is textual rather than policy-driven: Rule 402 sets a permissive baseline, Rule 702 speaks specifically to expert testimony and says nothing about general acceptance, and “a rigid ‘general acceptance’ requirement would be at odds with the ‘liberal thrust’ of the Federal Rules.” 509 U.S. at 588. What made the test vulnerable was its exclusivity: “Frye made ‘general acceptance’ the exclusive test for admitting expert scientific testimony.” Id. at 589.

Two qualifications follow, and both are routinely dropped. General acceptance was demoted, not rejected — the opinion lists it among the reliability considerations and says it “can yet have a bearing on the inquiry,” 509 U.S. at 594. And the displacement was federal only. A 1923 panel decision of the D.C. court was never binding on any state, so there was nothing for the Supreme Court to overrule as a matter of state law. Every state that has moved since has done so by its own decision, rule or statute — the District of Columbia itself only in 2016, ninety-three years after its own court decided the case.

On the point that carried the day the Court was unanimous. Chief Justice Rehnquist, joined by Justice Stevens, agreed that the Rules superseded the test and dissented only from the Court’s general observations about reliability.

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Published 2026-08-12