educational attainment before an expert will be per-
mitted to testify about a relevant diagnosis. For exam-
ple, while a court might permit a social worker with
relevant experience to testify that it is not unusual for
rape victims to fail to immediately report an assault, it
is likely to require clinical certification to diagnose
the alleged victim as suffering from posttraumatic
stress disorder. Similarly, courts usually demand a
medical degree to support testimony about drug treat-
ment or the effects of a particular drug regime on
human behavior.
Perhaps the most pressing issue presented in the
context of expert testimony is whether experts must
demonstrate specialized knowledge of the subject of
the testimony. The hallmark of contemporary science
(and all expertise) is specialization. This trend leaves
courts somewhat uncertain as to whether generalists
should be permitted to testify about matters that are
highly specialized. Courts tend to approach this mat-
ter flexibly. In practice, this means that the matter is
within the trial court’s discretion. Some courts require
experts to have demonstrated expertise in the specific
areas and topics on which they are to testify. Other
courts provide that generalists may testify on specialty
areas and that their lack of expertise in those areas is
a matter of weight for the trier of fact.
All the general issues presented regarding the quali-
fications of experts to testify can be found in the many
legal contexts in which training and experience in psy-
chology might assist triers of fact. Indeed, psychology
possibly illustrates better than any other field the com-
plexities associated with measuring an expert’s qualifi-
cations. Psychological expertise comes in myriad forms
and is introduced for a great variety of purposes. As
a general matter, as is true with other areas of substan-
tive expertise, an expert psychologist’s qualifications
depend on the nature of his or her proffered testimony.
A witness proposing to testify on the unreliability of
eyewitnesses, for example, would be expected to be
steeped in the research in this area. A witness proffered
on whether a defendant suffered from posttraumatic
stress disorder would be expected to have clinical
expertise. These two examples roughly represent the
two basic domains in which psychologists are offered
to testify: research-based knowledge and clinical opin-
ion. Each of these domains presents special difficulties
with regard to qualifications, not least because there is
no obvious line that divides the two.
In a number of legal contexts, psychological
research is relevant to general background facts, evenif the expert cannot reliably testify regarding how
those circumstances affected the particular case.
Specifically, research studies can often assist the trier
of fact to understand the background context regarding
some matter that is relevant to the case at hand. For
example, researchers might offer to testify regarding
the suggestibility of young children to leading ques-
tions in a case involving sexual assault, but they may
be unable to provide a reliable opinion regarding
whether a particular child’s testimony was influenced
by the questioning that occurred in the case at hand. A
witness proposing to testify regarding general research
results should generally have expertise in the relevant
literature as well as in statistics and research design.
Very often, an expert proffered to testify regarding a
particular research area will be someone who has pub-
lished extensively on the subject—though this would
not be a prerequisite in most jurisdictions.
In many cases, expert psychological evidence will
also be proffered on an issue that is particular to the
case. In theory, the proponent of such testimony has
the obligation to demonstrate the admissibility of both
the general framework and the framework’s applicabil-
ity to the particular case. With regard to expert qualifi-
cations, at least in theory, this means that an expert
must be qualified on the research basis for the general
framework and the clinical application of that research
framework to particular cases. This will often mean
that different experts will testify to these two subjects.
Consider, for example, a defendant who claims that
she killed in self-defense based in part on the battered
woman syndrome. As an initial matter, the defendant
has the burden to demonstrate the basic validity of the
claimed syndrome. This is a claim that ought to be
premised on the research literature and should be intro-
duced by an expert qualified to discuss the strengths
and weaknesses of that literature. Additionally, the
defendant is likely to proffer an expert opinion that she
suffered from the syndrome. This very often requires
the introduction of an additional expert, one qualified
to offer clinical expert testimony that is relevant and
reliable for the particular claim.
It must be emphasized that the issue of qualifica-
tions is intrinsically bound to the associated standards
for admissibility of the substantive expert testimony.
In federal cases, for example, this means that the
admissibility inquiry will be parallel to the determina-
tion made under Rule 702 and Daubert v. Merrell Dow
Pharmaceuticals(1993) and its progeny. Accordingly, if
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