20 www.DFInews.com FALL 2013
are testifying. In many cases the opposing attorney may
also contact you. This is a good thing. If you are working for the state in a criminal case, you should welcome
a meeting with the defense attorney. The attorney will
have the opportunity to review the tests you did and
the significance of the results obtained in a much less
formal manner than when you are testifying on the
witness stand. This is a perfect opportunity for you to
educate the attorney. It also shows that you are open
and unbiased. Since bias is the most common method
used to attack the credibility of a forensic expert, any
opportunity to let the attorney see how unbiased you are
can always be helpful. This meeting with counsel before
trial often reaps many benefits. You may even find your
testimony is less arduous.
I was recently asked if it was alright to talk to the
“opposing attorney” (the lawyer who did not call you to
testify) after you begin testifying, such as during a break.
My response was an energetic, “Of course!” If you find
yourself on a break during testimony and you haven’t
spoken with that attorney previously, introduce yourself and ask if the attorney has any questions. Usually,
lawyers will not have any questions, but will remember
that you were available to them outside the formal
setting of the courtroom. This willingness to share your
knowledge and conclusions goes a long way to make the
process less adversarial for the witness.
Question 2: Should you even say “I don’t know” on the
witness stand? Doesn’t it make you sound inadequate as
It goes without saying that the expert will understand
the scientific basis of the testing that was done. However, even the most educated and experienced persons
have gaps in their knowledge and experience. In most
cases, what you don’t know will have no effect on the
outcome of a trial. The exception to this is if you admit
you are not familiar with a certain basic process or fact
that is an essential part of your area of expertise. The
expert should also be familiar with other techniques and
procedures that may be conducted in other laboratories.
These should never be in the “I don’t know” category.
However, certain activities that took place before the
expert received the evidence, subsequent activities and
collateral matters may not be familiar. If you are asked
a question and you do not know the answer, you should
answer clearly, “I don’t know.” Never speculate. Nev-
er say “I imagine.” Never try to reason out the “best”
answer. This can lead to disastrous results. Once you say
you do not know the answer to a question, the attorney
can repeat that question only so many times before the
court will stop the repeated questioning, the other at-
torney will object, or the jury will get bored or annoyed.
If you are thoroughly prepared, the situations that arise
where you must express a lack of knowledge should be
minimal and logical based on your role in the case.
Question 3: What do I do if asked a question outside my
field of expertise?
It is well known that many attorneys are not thoroughly
versed in the different forensic disciplines. In addition, lawyers may not grasp the subtle boundaries of a
witness’s expertise. As with the “I don’t know” question,
the best approach is to be honest and straightforward.
If asked a question concerning a topic that is different
from or tangentially related to your expertise, merely
restate your expertise and that the question is outside
your area. There is no need to explain further. The
attorney may attempt to ask you the question in several
ways, but just continue testifying that the subject is
outside your expertise. Ultimately, you will appear more
credible to the jury if you continue to insist on limiting
the questions to your knowledge base.
Question 4: How do you correct a fact or conclusion that
has been misstated by the attorney?
Sometimes attorneys will misstate your testimony or
conclusions hoping to catch you in a contradiction or
to provide information to support their cases. Usually,
however, these errors are not intentional and may be
misspoken or misunderstood information. Once again
the best solution is the most straightforward. Before
answering the question, restate the premise correctly.
For example, if the attorney says that the fiber analysis
resulted in a match of two fibers, the expert could respond, “We do not say that fibers are ‘matched’ by these
methods, but results of these analyses did show the fibers
to have similar microscopical and instrumental characteristics.” This restates the limitations of the tests for the
trier of fact and prevents the witness from agreeing tacitly
to the use of inappropriate terms. Once expert witnesses
have finished testifying, they cannot control the language
used by attorneys during other court proceedings. While
still on the stand, however, it is the expert’s responsibility
If asked a question concerning a top-
ic that is different from or tangentially
related to your expertise, merely restate
your expertise and that the question is
outside your area.