For your expert witnesses under the gun of
cross-examination, usually the most problematic answer is a flat “yes” or “no.”
Science holds few absolutes to be true, thus most scientists (which is the
majority of your experts) are uncomfortable with an uncategorical “yes” or “no”
in response to many of opposing counsel’s questions.
Yet opposing counsel has one goal in mind: get that expert
to say “yes” to certain questions and “no” to certain others.
A useful technique is to suggest to your expert that he/she
respond with a qualifier in front of their “yes” or “no,” such as: “In this
situation, yes.” “Under certain conditions, no.” “When X is detected, yes.” “In
the presence of Y, no.” And so on.
These responses open the door to asking your witness later, why he/she qualified their answer in
such a manner.
Now, here’s where it gets really interesting: the results of
meta-research on 107 different studies conducted over 50 years on persuasion
and sidedness* show that two-sided arguments are more persuasive than their
one-sided equivalents, as long as counter-arguments are raised when presenting
the opposing view.
So, in telling the jury the rationale behind the qualifier,
the expert can present his/her thinking as, for example; “It could be said, as
opposing counsel’s expert stated, that …, however, studies show that …, which
is why my opinon is …” which format serves to present the two sides of the
argument, and raises the counter argument.
According to the meta-research, not only is such an approach
more convincing, it also boosts the speaker’s credibility.
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*Daniel O’Keefe, 1999, Communication
Yearbook, 22, pp. 209-249