example, the complaint in Daubert v. Merrell Dow
Pharmaceuticals(1993) itself. The plaintiffs claimed
that Jason Daubert’s mother’s ingestion of Bendectin
during pregnancy caused or contributed to his birth
defects. This claim had both general and specific com-
ponents. As a matter of general causation, the plain-
tiffs were obligated to show that Bendectin sometimes
causes birth defects. This hypothesis transcends the
particular dispute and is as true in California as it is in
New York. In addition, the plaintiffs had to show that
Jason’s birth defects were attributable to his mother’s
ingestion of Bendectin. This proof might involve
showing that she took the drug during the relevant
period of gestation and that other factors did not cause
the defects. This is specific causation.
Virtually all scientific evidence shares this basic
dichotomy between the general and the specific.
Science provides methods by which relationships or
associations can be identified and, typically, quantified.
Scientific theories often involve induction from the par-
ticular to the general. The law, however, needs to apply
these general lessons to specific cases. Although still
little appreciated among psychologists, this division
between what scientists do and what the law needs is
one of the areas needing the greatest attention by those
interested in the psychology-and-law connection.David L. FaigmanSee also Expert Psychological Testimony; Expert
Psychological Testimony, Admissibility Standards; Expert
Testimony, Qualifications of ExpertsFurther Readings
Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993).
Davis, K. C. (1942). An approach to problems of evidence in
the administrative process. Harvard Law Review, 55,
364–425.
Monahan, J., & Walker, L. (1986). Social authority: Obtaining,
evaluating, and establishing social science in law.
University of Pennsylvania Law Review, 134,477–517.
Monahan, J., & Walker, L. (2002). Social science in law:
Cases and materials(5th ed.). Westbury, NY: Foundation
Press.
Walker, L., & Monahan, J. (1987). Social frameworks: A new
use of social science in law. Virginia Law Review, 73,
559–598.
Walker, L., & Monahan, J. (1988). Social facts: Scientific
methodology as legal precedent. California Law Review,
76,877–896.EXPERTPSYCHOLOGICALTESTIMONY
ON EYEWITNESSIDENTIFICATION
Psychologists occasionally testify about the factors
that influence eyewitness identification accuracy in
criminal cases in which eyewitness identification is a
pivotal issue. Considerable research has addressed the
need for this testimony and its impact on the jury.
Typically, the expert witness is trained in cognitive or
social psychology and has published scholarly work
about eyewitness identification accuracy. Most often,
the expert witness is offered by the attorney for the
defendant. In such cases, the expert undergoes “direct
examination” by the defense attorney and “cross-
examination” by the prosecuting attorney.
The purpose of this form of expert testimony is to
educate the jury about the factors that are known from
research to influence the likelihood of false identifica-
tion. The content of the expert testimony typically
focuses on issues such as factors affecting the likeli-
hood of mistaken identification, the suggestiveness of
lineup and photoarray procedures, and the relation
between eyewitness confidence and identification
accuracy. For example, with respect to witnessing fac-
tors, an expert might testify that witnesses are more
likely to make false identifications when identifying a
perpetrator of another race than when identifying a
perpetrator of their race. Extreme stress associated
with a violent crime inhibits a witness’s ability to accu-
rately encode information. The presence of a weapon
creates a “weapon focus” effect and increases the like-
lihood of false identification. With respect to lineups,
an expert witness might testify that false identifications
are more likely with suggestive lineup instructions and
when lineup members are presented simultaneously
rather than sequentially. An expert witness might also
testify that eyewitness confidence is not strongly
related to identification accuracy and that eyewitness
confidence levels can be inflated by information pro-
vided by cowitnesses or investigators that validates the
eyewitness’s selection from the lineup. Expert wit-
nesses do not offer opinions about the accuracy of eye-
witness identification in a given case.
The decision to admit expert psychological testi-
mony about eyewitness identification into court is
normally left to the discretion of the trial judge, and
the likelihood of admission varies considerably from
state to state and in federal courts. Typical reasons
for excluding expert psychological testimony about278 ———Expert Psychological Testimony on Eyewitness IdentificationE-Cutler (Encyc)-45463.qxd 11/18/2007 12:42 PM Page 278