Admissability of Scientific Evidence – Daubert v. Merrell Dow (1993)

The U.S. Supreme Court’s opinion in Daubert v. Merrell Dow (1993) rejected the Frye  test and Frye-plus tests for the admissibility of certain scientific evidence (see admissibility tests lecture).  Instead of “general acceptance” in the scientific community, the Daubert test requires an independent judicial assessment of reliability.  Among other purposes, the Daubert test is intended to end the current “battle of the experts” state of affairs. The Daubert decision involved the claim that Bendectin caused birth defects, and even though it was intended to clear the way for admitting novel scientific evidence (like DNA), it has instead turned out to be a firestorm of controversy.

The misuse of scientific evidence is a serious problem. Even the FBI laboratory is under suspicion. In West Virginia, a serologist falsified test results in hundreds of cases over a ten-year period, sentencing hundreds of defendants to lengthy prison terms. In Texas, a pathologist faked autopsy results, resulting in as many as 20 death penalty verdicts. A police chemist elsewhere falsified reports and sent hundreds of innocent people away to jail on rape charges. Most misuse of scientific evidence is pro-prosecution. Daubert sheds light on shoddy procedures, protocols, and proficiency testing.

This document attempts to understand the Daubert test in light of continuing battles over forensic techniques and procedures. The Daubert ruling rests on an interpretation of the Federal Rules of Evidence. As a statutory, rather than constitutional case, it is not necessarily binding on the states, but many courts of appeals are ordering remands or whole new hearings because the trial court failed to conduct a Daubert hearing, and there is frequent variation from state to state in how Daubert hearings are conducted.

The fact is that Frye still remains the rule in many states. Other states have adopted Daubert, and yet other states have a history of rejecting Frye  and Daubert, substituting their own standards. The following table contains a summary:

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  States accepting Daubert:


  States sticking with Frye:

States with their own tests, or typically a Frye-plus test.

New Mexico
South Dakota
West Virginia

New York

North Carolina

Of course, all this is subject to change, but was fairly accurate as of 2004, and I continue to get emails from people updating my information. States in the third category, like North Carolina, express a variety of standards, but generally use a balancing test approach, balancing relevancy or materiality with prejudicial effect which, in North Carolina, has been noted as “consistent with Daubert” (see State v. Goode, 341 N.C. 513, 461 S.E.2d 631 (1995)).


JUDICIAL NOTICE: The theoretical foundations behind many sciences are so firmly established as scientific laws that they are more properly the subject of judicial notice; the judge should be able to make a determination.

ADMINISTRATIVE LAW: Some techniques and procedures have such an extensive precedent in administrative law as to be part of official manual/standard operating procedure for agencies; it is wide-ranging precedent. CERTIFICATION: Scientific fields that have been generally accepted by professional forensic associations are proliferating, forensic this and forensic that; there must be some underlying reliability standards.

CODIFICATION: Daubert may provide the impetus to amend Fed. Rule 702 and its state counterparts which have created a variety of tests such as the “modified Frye Rule”, the “Frye Plus Rule”, the “objectively verifiable rule”, and “three-prong rules”.

Let’s look at some common statements of FRYE and DAUBERT.


  Interpretation of Frye:

  Interpretation of Daubert:

Where novel scientific evidence is at issue, the Frye inquiry allows the judiciary to defer to scientific expertise precisely as to whether or not it has gained “general acceptance” in the relevant field. The trial court’s gatekeeper role in this respect is conservative, thus helping to keep “pseudoscience” out of the courtroom.

  General acceptance is an austere standard absent from and incompatible with the Rules of Evidence. “Scientific knowledge” must be derived from the scientific method supported by “good grounds& validating the expert’s testimony, establishing a standard of “evidentiary reliability.”

The Daubert ruling substitutes a reliability test for a relevancy test.For states that follow neither Frye nor Daubert, this means that the continued practice of using reliability as a weight once relevancy has been established exposes a serious constitutional liability.


All trial courts make a preliminary determination of admissibility. This job involves a preliminary assessment of whether the evidence is relevant, competent, and material. In short, can the evidence be properly applied to the facts in this case? This is the traditional “gatekeeping” function of courts. A number of reliability factors can enter into this and subsequent hearings using the Daubert  standard.

  • Has the scientific theory or technique been empirically tested? According to K. Popper (1989) in The Growth of Scientific Knowledge, “the criterion on the scientific status of a theory is its falsifiability, refutability, and testability.”
  • Has the scientific theory or technique been subjected to peer review and publication? This ensures that flaws in the methodology would have been detected and that the technique is finding its way into use via the literature. 
  • What is the known or potential error rate? Every scientific idea has Type I and Type II error rates, and these can be estimated with a fair amount of precision. There are known threats to validity and reliability in any tests (experimental and quasi-experimental) of a theory.
  • What is the expert’s qualifications and stature in the scientific community? And does the technique rely upon the special skills and equipment of one expert, or can it be replicated by other experts elsewhere? 
  • Can the technique and its results be explained with sufficient clarity and simplicity so that the court and the jury can understand its plain meaning? This is just the Marx standard, which is assumed to be incorporated in Daubert as it was with Frye.

(Note this is not a complete list, and is not accurate for ALL jurisdictions.

BALLISTICS generally FAILS the Daubert  standard despite widespread acceptance.

BATTERED WOMAN SYNDROME has satisfied the Daubert standard in some jurisdictions, but fails in most.

CHILD ABUSE ACCOMMODATION SYNDROME has FAILED the test, for the most part.

COMPUTER SIMULATION has failed because experts often can’t explain the algorithms.

DNA evidence is admissible under either the Frye or Daubert standard, but the reliability issue goes beyond the matter of testimony to the proper performance of protocols and probability estimates.

EYEWITNESS IDENTIFICATION generally FAILS the Daubert test, for the most part, as most social science, like social psychology, does.

FORENSIC ANTHROPOLOGY has not yet met the Daubert test, but the study of certain features from bones remains reliable.

HAIR ANALYSIS. Daubert has been successfully applied to Spectrophotometer and Gas Chromatographic tests for detecting the past use of drugs.

HYPNOSIS has known therapeutic value, but not as a method of producing accurate recollection of past events, as it would be used in court. Hypnosis, therefore, does not meet the Daubert test.

INTOXILYZER TESTS have been ruled valid and are considered beyond scientific dispute by many judges.

POLYGRAPH evidence (which was usually acceptable under Frye with a few exceptions) is beginning to be found reliable in Daubert hearings, but still does not enjoy widespread acceptance, and is, in fact, outlawed by per se laws in various jurisdictions.

PSYCHIATRIC evidence has had mixed results under Daubert. Techniques such as use of penile plethysmography to measure sexual arousal have had problems getting admitted in some states, but have faced no problems in other states. Also having difficulty is psychological or sociopsychological profiling which is often attacked for its lack of logical foundation and/or weak methodology. Checklist techniques, such as those used to determine if someone is a pedophile or a psychopath (e.g., an Axis disorder on the DSM IV) are even experiencing difficulties. However, testimony regarding mental disorders that go to the matter of mens rea  generally satisfies the Daubert test as does much diminished capacity testimony and the more proven variety of syndromes.

QUESTIONED DOCUMENTS (or Expert Handwriting Analysis) has been ruled by many judges as not requiring the Daubert test because scientific principles have nothing to do with the day to day tasks as performed by practicing QDEs. However, some newer types of analysis are experiencing difficulties.

SOCIAL SCIENCE evidence, such as the use of regression analysis to show evidence of racial bias or estimates of damage, often requires the addition of proof from the field of epidemiology and some demonstration of mastery at econometrics, but “naked” statistical evidence has often been admitted anyway by some judges.

TRACE EVIDENCE COMPARISON has not yet been decided due to controversy over the qualifications required for a forensic scientist or lab technician as a microanalyst.

VOICE COMPARISON techniques have FAILED the Daubert test, for the most part.


Blog 702

Daubert on the Web

Daubert Tracker from MDEX Online

RAND Report on Admitting Scientific Evidence


Berger, M. (2000). “The Supreme Court’s Trilogy on the Admissibility of Expert Evidence,” Reference Manual on Scientific Evidence. Washington D.C.: Federal Judicial Center.

Dixon, L. & Gill, B. (2002). Changes in the Standards for Admitting Expert Evidence in Federal Civil Cases Since the Daubert Decision. Santa Monica: CA: RAND.

Giannelli, P. (1994). “Daubert: Interpreting the Federal Rules of Evidence.” Cardoza Law Review 15: 1999-2026.

Golan, T. (2004). Laws of Men and Laws of Nature: The History of Scientific Expert Testimony in England and America. Cambridge, MA: Harvard Univ. Press.

Huber, P. (1993). Galileo’s Revenge: Junk Science in the Courtroom. NY: Basic Books.

Jasanoff, S. (1997). Science at the Bar: Science and Technology in American Law. Cambridge, MA: Harvard Univ. Press.

Kiely, T. (2005). Forensic Evidence: Science & The Criminal Law, 2e. Boca Raton, FL: CRC Press.

Lubet, S. (1999). Expert Testimony. NY: National Institute for Trial Advocacy.

Spiegel, M. (1994). Admissibility of expert testimony: Daubert and Beyond. Washington D.C.: ABA Section on Litigation.

Wecht, C. & Rago, J. (Eds.) (2005). Forensic Science and Law. Boca Raton, FL: CRC Press.

  Last updated: 02/05/06

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