The conflicting lines of
authority, whether to use Frye, Federal Rule of Evidence 702, or a
hybrid of the two, remained unreconciled until the Supreme Court granted
review in Daubert v. Merrell Dow Pharmaceuticals, Inc. Interestingly,
significant impetus for review of the case may have come from within the
judicial rulemaking process. In June 1991, the Advisory Committee on
Civil Rules of the Judicial Conference of the U.S. proposed amendments
to both the Federal Rules of Civil Procedure and the Fed. R. Evid. The
amendments included a revised Rule 702, which would have allowed the
admission of expert testimony only if it was "reasonably
reliable" and would "substantially assist the trier of fact to
understand the evidence or to determine a fact in issue." The
Committee Notes suggested that this revision was intended to limit the
use, while increasing the utility and reliability, of expert testimony.
The proposal contemplated that the courts should "reject testimony
that is based upon premises lacking any significant support and
acceptance within the scientific community." The Committee summary
further indicated an intent to address unwarranted increases in
litigation costs resulting from the use of unreliable expert testimony.
The Supreme Court's Order of April 22, 1993,
adopted many of the civil rule amendments proposed by the Committee.
These amendments were part of the comprehensive changes which became
effective Dec. 1, 1993. The Court, however, granted certiorari in
Daubert on October 13, 1992, and the proposed modification of Rule 702
did not emerge from the rulemaking process. Instead, the Court addressed
the Committee's concerns in Daubert.
Daubert is now the best known of the many products
liability cases involving the anti-nausea drug Bendectin. During the
1980s, approximately 1700 actions were brought alleging that the drug
caused birth defects. Plaintiffs Jason Daubert and Eric Schuller were
minor children born with serious birth defects. They sued Merrell Dow
alleging that Bendectin caused their injuries.
Merrell Dow moved for summary judgment in the
district court, arguing that Bendectin did not cause birth defects in
humans and that petitioners could offer no admissible evidence to
support theirclaim. Merrell Dow supported its motion with an affidavit
of a physician whom Justice Blackmun, writing for the Court, described
as a "well-credentialed expert on the risks of exposure to various
chemical substances." The affidavit stated that none of the more
than thirty published epidemiological studies involving over 130,000
patients had found Bendectin to be capable of causing malformations in
fetuses and concluded that Bendectin was not a risk factor.
The plaintiffs did not dispute the description of
the published research, but rather presented the testimony of eight
experts whose credentials the court noted were also
"impressive." The experts, testifying that Bendectin could
cause birth defects, based their testimony on test tube and live animal
studies suggesting causation, analyses of pharmacological similarities
between Bendectin and other substances known to cause birth defects, and
reanalyses of the published studies on Bendectin.
The district court examined plaintiffs' evidence
under the Frye standard, which the 9th Circuit had reaffirmed in U.S. v.
Kilgus. The court recognized the extensive body of generally accepted
epidemiological data available on Bendectin. Consequently, it held that
plaintiffs' test tube, live animal, and pharmacological studies, which
were not based on epidemiological data, could not be admitted to prove
causation. The court further held that plaintiffs' reanalyses of the
published epidemiological studies were inadmissible because plaintiffs'
experts had not published these studies and their peers had not reviewed
them. Under the district court's analysis of the evidence, the
plaintiffs offered no proof that Bendectin caused their birth defects
and therefore it granted Merrell Dow's motion for summary judgment.
The 9th Circuit affirmed and discussed the Frye
rule - that expert opinion based on a scientific technique is
inadmissible unless the technique is generally accepted as reliable by
the relevant scientific community. Evidence based on techniques that
diverged significantly from techniques accepted by recognized
authorities in the field, the court reasoned, could not meet the
standard of general acceptance. The medical field generally accepted
epidemiological studies to show causation of birth defects, and
therefore the court did not permit other evidence of causation to be
admitted. Thus, the 9th Circuit concluded that the district court
properly excluded plaintiffs' test tube, live animal, and
pharmacological studies, and had correctly excluded plaintiffs' evidence
based on reanalyses of epidemiological data. While the medical community
utilized reanalyses, such studies were generally accepted only after
they were subjected to review by others in the field. The reanalyses in
question had been prepared for the Daubert litigation and had not been
reviewed by the scientific community. According to the 9th, it did not
suffice that scientific proof met some of the requirements of the
scientific community; the evidence had to meet all of the essential
requirements and so upheld the exclusion of the reanalyses.
The Supreme Court granted review in Daubert to
resolve the "sharp divisions regarding the proper standard for
admission of expert testimony." The primary issue presented was
whether the adoption of Fed.R. Evid. 702 eliminated the general
acceptance test of Frye for the admission of scientific evidence.
Secondarily, the Court was asked to consider whether, if Frye remained
valid,Rule 702 required that expert scientific testimony undergo peer
review to be admissible in evidence.
The Justices unanimously held that the adoption of
the Fed.R. Evid. superseded Frye. Interpreting the
legislatively-approved rules as it would any statute, the Court found
that nothing in the text of Rule 702 required general acceptance as a
foundation for the admission of scientific evidence, and there was no
clear indication that the drafters intended the new rules to incorporate
this standard. The Court construed the drafters' omission of any
reference to the Frye test in either the text or the Committee Note as
indicating that Frye was no longer good law. Moreover, in the Court's
view, this rigid test was incompatible with the "liberal
thrust" of the Fed.R. Evid. and henceforth should no longer be
applied in federal trials.
In place of Frye, the majority articulated a
two-part test, directing that "the trial judge must ensure that any
and all scientific testimony or evidence admitted is not only relevant,
but reliable." According to the Court, the primary source of this
duty is the language of Rule 702, which first requires that the expert
testimony convey "scientific knowledge." This characterization
indicates that purported scientific testimony must be based on
"scientific method or procedure" and comprise more than
"subjective belief or unsupported speculation." Scientific
testimony need not be certain, but must meet a standard of evidentiary
reliability or trustworthiness. Rule 702's use of the term
"knowledge" required that the testimony be supported by
appropriate validation consisting of "good grounds based on what is
known."
In addition, the majority explained, Rule 702
requires that there be a sufficient "fit" between the
scientific testimony and the facts of the case so that the testimony
will assist the trier in finding the facts. Displaying uncharacteristic
whimsy, Justice Blackmun explained that absent an acceptable showing of
such a nexus, evidence on the phases of the moon indicating that it was
full on a certain night could not be received to show that a particular
individual was behaving irrationally on that evening. He cautioned,
however, that this relevance determination will not always present an
obvious question, as the validity of scientific evidence can vary
depending on the purpose for which it is used.
A court exercising its gatekeeping function
regarding a proffer of expert scientific evidence must find that the
proponent has established, by a preponderance of the evidence, the
foundation facts. In making this preliminary determination, however, the
court is not bound by the evidentiary rules. The Court identified some
of the factors which bear on the determination as to whether the
evidence is scientific, but did not attempt to provide a definitive
checklist.
Ordinarily, a key question is whether the
proffered theory or technique can be and has been tested. As the Court
noted, "'scientific methodology today is based on generating
hypotheses and testing them to see if they can be falsified.'" A
second consideration is whether the theory or technique has been
subjected to peer review and publication. Although publication is not
necessary for admissibility, and in some instances may not ensure
reliability, exposure to the review process supports admission because
it increases the likelihood that the scientific community will detect
any error that exists. For particular techniques, the district court
should consider the known or potential rate of error and any
professional standards that may be applicable. Lastly, the court may
still consider the general acceptance of a technique by explicitly
identifying a relevant scientific community and expressly determining
the degree of acceptance in that community. "Widespread acceptance
can be an important factor" in admitting evidence, and the district
court may be properly skeptical of a known technique that has garnered
only minimal support within the community.
The Daubert opinion emphasized that the district
court should be flexible in conducting its inquiry and should focus on
the principles and methodology that underlie the evidence, not on the
conclusions they generate. The Court acknowledged its reliance on
Downing and, in an obvious invitation to the lower courts to expand on
the factors enumerated in the majority opinion, suggested that the
approaches offered by the 3rd Circuit and a number of other sources on
the reliability determination "may well have merit."
The majority cautioned that a district court
considering a proffer must be mindful of other rules of evidence. Expert
evidence based on otherwise inadmissible hearsay may be admitted
pursuant to Rule 703 only if the underlying facts or data are of a type
"reasonably relied upon by experts in the field in generating
inferences or opinions upon the subject." Rule 706 authorizes the
court to appoint an expert to assist with the case. In addition, the
court may exclude evidence under Rule 403 "if its probative value
is substantially outweighed by the danger of unfair prejudice, confusion
of the issues, or misleading the jury." The majority noted that
this provision allows judges greater control over experts than other
witnesses, as "'expert evidence can be both powerful and quite
misleading because of the difficulty in evaluating it.'"
Daubert concluded by responding to some of the
policy concerns expressed by the opposing parties and numerous amici in
the case. The Court stated that it did not expect that the abandonment
of Frye would result in a free-for-all in which juries would
beconfounded by "pseudoscientific" offerings. Merrell Dow was
"overly pessimistic" about the ability of the jury to address
scientific evidence, and the efficacy of the adversary system. At trial,
vigorous cross-examination, introduction of opposing evidence, and
careful jury instructions as to the burden of proof adequately address
the potential problems presented by "shaky but admissible
evidence." Moreover, if a court believes that the evidence is
insufficient to support a favorable finding by a reasonable juror, the
court may either direct a judgment at trial or grant summary judgment.
The Daubert majority was satisfied that these
devices adequately insure the integrity of the truth-seeking process
where scientific evidence is admitted in a case. Unlike scientific
inquiry, legal fact finding is generally not subject to revision as
additional data becomes available, but rather must settle issues within
the constraints of a dispute resolution procedure. While the gatekeeping
role played by a judge may occasionally result in the exclusion of
valuable insights, the rules of evidence sanction this balance in order
to resolve issues in the context of the legal process.
Justice Stevens joined Chief Justice Rehnquist in
partial dissent. While agreeing that Frye did not survive the enactment
of the Fed.R. Evid., these Justices disassociated themselves from the
Court's effort to sketch the contours of the new test, calling the
Court's observations "not only general, but vague and
abstract." They expressed concern that the scientific subject
matter of the briefs was outside the expertise of the judiciary. In
particular, they questioned the competence of federal judges to decide
in the first instance whether a scientific theory can be and has been
tested. While not disputing the appropriateness of a gatekeeping
function, they cautioned that amateur science was not within the
jurisdiction of the courts.
While courts and commentators have debated at some
length whether Daubert will affect the admissibility of various types of
scientific evidence, Daubert did not contemplate a revolutionary change
in the practice of the federal courts. In particular, the Court retained
Frye's general acceptance standard as an "important factor"
bearing on admissibility. Under the Court's formulation of the standard
for Rule 702, district courts are free to retain all prior jurisprudence
on the reliability of various scientific methods. At the same time,
Daubert's emphasis that the inquiry it envisioned was to be "a
flexible one" is calculated to allow the trial court to scrutinize
the reliability of techniques that it views with skepticism, even when
proponents have shown general acceptance. Daubert, however, also affords
the district court the freedom to consider new methods of proof for
which no such claim of acceptance can yet be made.
