Daubert v. Merrell Dow Pharmaceuticals, Inc.

In a 1923 case, Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), the D.C. Circuit held that evidence could be admitted in court only if "the thing from which the deduction is made" is "sufficiently established to have gained general acceptance in the particular field in which it belongs." Frye dealt with a systolic blood pressure deception test, a "crude precursor" to the polygraph. In 1923, this blood pressure test was not widely accepted among scientists, and so the Frye court ruled it could not be used in court. Over the years, scholars disputed the proper scope and application of the Frye test.

The plaintiffs successfully argued that after Congress adopted the Federal Rules of Evidence in 1975, Frye was no longer the governing standard for admitting scientific evidence in trials held in federal court. The Supreme Court agreed and had already ruled that where common law rules conflicted with provisions of the Rules, the enactment of the Rules had the effect of supplanting the common law. Frye was certainly part of the federal common law of evidence because it was decided almost 50 years before the Rules were enacted. But the text of the Rules did not suggest that Congress intended to keep the Frye rule, and so the Court reasoned that Frye was no longer the rule.

Rule 702 of the Federal Rules of Evidence provides (in part):

If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise...

The text of Rule 702 did not make admissibility of expert testimony depend on general acceptance, and there was no evidence that Congress intended to incorporate a general acceptance standard into Rule 702. "Given the Rules' permissive backdrop and their inclusion of a specific rule on expert testimony that does not mention 'general acceptance,' the assertion that the Rules somehow assimilated Frye is unconvincing. Frye made 'general acceptance' the exclusive test for admitting expert testimony. That austere standard, absent from, and incompatible with, the Federal Rules of Evidence, should not be applied in federal trials."[1]

Three key provisions of the Rules governed admission of expert testimony in court. First, scientific knowledge, meaning that the testimony must be scientific in nature and must be grounded in "knowledge." Of course, science does not claim to know anything with absolute certainty; science "represents a process for proposing and refining theoretical explanations about the world that are subject to further testing and refinement." The "scientific knowledge" contemplated by Rule 702 had to be arrived at by the scientific method.

Second, the scientific knowledge must assist the trier of fact in understanding the evidence or determining a fact in issue in the case. The trier of fact is often either a jury or a judge; but other fact finders may exist within the contemplation of the federal rules of evidence.[2] To be helpful to the trier of fact, there must be a "valid scientific connection to the pertinent inquiry as a prerequisite to admissibility." For example, although it is within the purview of scientific knowledge, knowing whether the moon was full on a given night does not typically assist the trier of fact in knowing whether a person was sane when he or she committed a given act.

Third, the Rules expressly provided that the judge would make the threshold determination[3] regarding whether certain scientific knowledge would indeed assist the trier of fact in the manner contemplated by Rule 702. "This entails a preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue." This preliminary assessment can turn on whether something has been tested, whether an idea has been subjected to scientific peer review or published in scientific journals, the rate of error involved in the technique, and even general acceptance, among other things. It focuses on methodology and principles, not the ultimate conclusions generated.

The Court stressed that the new standard under Rule 702 was rooted in the judicial process and intended to be distinct and separate from the search for scientific truth. "Scientific conclusions are subject to perpetual revision. Law, on the other hand, must resolve disputes finally and quickly. The scientific project is advanced by broad and wide-ranging consideration of a multitude of hypotheses, for those that are incorrect will eventually be shown to be so, and that in itself is an advance." Rule 702 was intended to resolve legal disputes and, thus, had to be interpreted in conjunction with other rules of evidence and with other legal means of ending those disputes.

Cross examination within the adversary process is adequate to help legal decision makers arrive at efficient ends to disputes. "We recognize that, in practice, a gatekeeping role for the judge, no matter how flexible, inevitably on occasion will prevent the jury from learning of authentic insights and innovations. That, nevertheless, is the balance that is struck by Rules of Evidence designed not for the exhaustive search for cosmic understanding but for the particularized resolution of legal disputes."