This paper traces the Supreme Court’s erratic course over the past fifteen
years in addressing the question whether federal judges may bar expert scientific
testimony on the ground that the testimony is “unreliable.” From the initial stance
that no such reliability threshold exists (Barefoot v. Estelle), the Court moved to
the view that there is a reliable threshold–expert testimony will be admitted only
when the expert’s methodology conforms to the dictates of “good science”
(Daubert v. Merrell-Dow Pharmaceuticals, Inc.), and more recently moved again,
this time to the view that district judges have broad discretion to admit or exclude
expert testimony based upon their assessment of the reliability of both the
methodology and the ultimate conclusions reached (General Electric Co. v.
Joiner). This journey has been marked from beginning to end with formalist
opinions that do not address the wisdom of the choices being made. The opinions
in Barefoot and Joiner announce their conflicting results simply as ipse dixits,
while the Daubert opinion relies solely on dictionary definitions of two words
(“scientific” and “knowledge”) in Rule 702 of the Federal Rules of Evidence
(“FRE”). Given that the controlling words in the Federal Rules of Evidence have
remained unchanged throughout the period of these decisions, dictionaries seem an
unsatisfying explanation for the divergent results.
This paper identifies the unarticulated reasons that likely explain this
erratic journey. It also critiques the holdings in Daubert and Joiner, using two
indices the Court did not consider: the intent of Congress when it enacted the FRE
in 1975, and the public good. Finally, the paper speculates on the future of expert
scientific testimony in light of the recent Joiner opinion.