As evidenced by the recent case of Moore v. Getahun, the scope of permissible
interactions between counsel and expert witnesses is a recurring
issue that arises from time to time when experts are called to
testify at trial. The Advocates' Society has recently developed
and approved a set of "best practices" that litigators
should consider following in their interactions with experts. I
will briefly summarize them, though a full review of the principles
and the position paper underpinning them may be found here.
Given a duty to present reliable, clear, comprehensible and
relevant expert evidence, an advocate can (and should in many
cases) have an appropriate degree of consultation with testifying
experts, including appropriate input into the format and content of
an expert's report or affidavit before it is finalized and
delivered. What is to be avoided is any communication likely to
interfere with the expert's duties of independence and
objectivity, which would result in a disservice to the expert, the
client and the court.
The advocate's duty when engaging an expert is to inform the
expert of his or her role in the process and of the nature and
content of the expert's duties, including the requirements of
independence and objectivity. Since there is a possibility that the
expert's file will be disclosed, the advocate should advise the
expert of same and counsel the witness not to destroy relevant
Further, the advocate must ensure that the expert witness
receives all relevant information and documentation concerning the
matters at issue and understands the issue on which the expert has
been asked to opine. The lawyer should advise the expert that this
receipt of information and documentation is subject to applicable
rules of confidentiality.
The expert witnesses must understand they are able to probe and
question information and assumptions provided to them before
completion of their analysis and/or expression of their opinions.
An advocate should discourage an expert from preparing a draft
report until the expert has a proper understanding of:
the issue to opine on;
the facts and assumptions upon which the opinion will be
the documentation and information relevant to the opinion
sought (irrespective of whether same is helpful or harmful to the
the need to confine his or her analysis, observation and
opinion to matters that lie within the expert's expertise.
This will assist the advocate in her/his obligation to take
reasonable steps to protect a testifying witness from unnecessary
A determination as to the appropriate degree of consultation
with a testifying expert and the appropriate degree of the
advocate's involvement in preparation of an expert's report
or affidavit will depend on several factors as well, including the
nature and complexity of the case in question, the level of
experience of the expert, the nature of the witness's
expertise, and other relevant circumstances of the case.
In appropriate cases, an advocate should also consider entering
into an agreement with opposing counsel relating to matters such as
agreed limits on disclosure of draft reports and communications
with experts, and limits on demands for production of the files of
The content of this article is intended to provide a general
guide to the subject matter. Specialist advice should be sought
about your specific circumstances.
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A recent decision of the Ontario Court
of Appeal, D'Onofrio v. Advantage
Car & Truck Rentals Ltd., 2017 ONCA 5,
asks whether a party who takes "no
position" on a summary judgment
motion is later bound by the motion
judge's findings in the ongoing
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