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trial) to understand the evidence or
decide a fact in dispute, and whether
your testimony is trustworthy.
In deciding whether your testimony is
trustworthy, the judge considers
whether your testimony is based on
sufficient facts and data, whether it is
the product of reliable principles and
methods, and whether your principles
and methods have been applied in a
reliable manner to the facts and data in
the case.
Judges exclude expert testimony if
there is too great an analytical gap
between the data and the opinion an
expert offers, if it is speculative or con-
jectural, or if it is based on assump-
tions that are too unrealistic. For a
discussion of cases in which judges
have rejected expert opinions as to lost
profits, see "Daubert
and Lost
Profits Testimony" (Trial Magazine,
September 2005). You will find a link to
that article at
Accordingly, in doing your work as a
testifying expert witness, be sure to
gather all facts and data reasonably
required for your analysis, and make
sure the sources of those facts and
data are reliable. You can rely on facts
and data you learn from others, if of a
type reasonably relied by CPAs in ren-
dering such opinions.
Do not speculate and, to the extent you
need to make assumptions, make sure
they are well-grounded. The methodol-
ogy you use in your analysis should be
generally accepted among CPAs.
Unless you follow these guidelines,
your opinion can be attacked for lack of
trustworthiness, and the judge may not
allow you to testify.
advocacy community education
Stewart I. Edelstein,
J.D. is chair of the
Litigation Group at
Cohen and Wolf,
P.C. and teaches
Civil Litigation
Practice at Yale Law
School. He has more than 35 years'
experience representing clients in all
aspects of commercial litigation. His
clients include Fortune 500 and other
national corporations as well as lead-
ing municipalities and individuals.
You can contact him at
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