Giving Evidence as an Expert Witness
| Author | Alan Gold and Hy Bloom |
| Pages | 59-88 |
CHAPTER 5
Giving Evidence as an Expert Witness
Alan Gold and Hy Bloom*
I. INTRODUCTION
Sooner or later most mental health professionals will assume the role of expert witness. is role,
depending upon circumstances, will involve to a lesser or greater extent the adversarial system. Testify-
ing in court means participating in an inherently adversarial system, and the demands and protocols
of testifying are very dierent from the demands met elsewhere in mental health practice. e expert
witness will exert litt le control over the proceedings and must understand a dierent technical language.
e outcome of any legal matter is beyond the witness’s purview. e essence, albeit exaggerated, of the
dierence is captured as follows:
e psychiatrist must be aware that going from a clinical setting into the judicial system is not unlike
Alice walk ing through the looking glass. ere are vast dierences bet ween legal and psychiatric termin-
ology, diagnoses, and concepts that must be considered (Wilkinson, 1997).
As an expert witness, the professional owes a duty to the retaining party, which is superceded by the
duty she owes to the court. e duty to the court may result in providing information and opinion evi-
dence that may go against the interests of the party by whom he was retained. In carrying out his duties,
he must also be sure to communicate in language appropriate to this very dierent audience.
is chapter is generally about the role of an expert witness. is role may specically be sought out
by professionals eager to grow a forensic practice; however, it may also be assumed by a mental health
professional whose primary role is therapeutic, but who has been conscripted into the role of expert be-
cause of some medico-legal scenario her patient has become involved in. e purpose of the chapter is to
assist the mental health professional to understand the relevant principles and requirements of the role,
and also to appreciate the preparatory steps and other measures and eorts that make a better expert
witness.
Clinicians who are unaccustomed to the role of expert, trainees, novices in medico-legal psychiatry,
and even clinicians who work in the eld, oen greet the prospect of going to court with trepidation.
Understanding the legal process, having an intimate familiarity wit h the scope and limits of the expert’s
role, as well as one’s personal abilities and limitations, are essential in allaying an xiety. Dvoskin and Guy
(2008) suggest that being aware of and managing the expert’s “narcissistic needs” (for admiration, win-
ning, and being valued) and that taking a more “humble stance, [by] think[ing] of themselves simply as
evidence,” will go a long way toward dispelling any anxiety and uncertainty.
Psychiatric consultation is sought for a widely diverse number of legal proceedings. A full but non-
exhaustive list of potential uses of psychiatric consultation and evidence in criminal and civil proceed-
ings was set out Tables 2.1 and 2.2 in Chapter 2.
Recent enquiries into the uses and abuses of medical and other expertise in the courts (Kaufman
Commission, 1997; Goudge Report, 2008) have cast a shadow on the professionalism and integrity of
* is chapter is a revi sed version of an earlier publication, Bloom & Bay (1996), Carswel l. Reprinted by permission.
Alan Gold and Hy Bloom
medical (and other) experts. Lawyers and the courts are now wary of the tr aining and objectivity of these
experts. is will no doubt result in greater scrutiny, rather than diminished use of experts. In R. v. Ab-
bey (2009), Justice Doherty articulated the dilemma for the courts as follows (p. 354):
Despite justiable misgivings, expert opinion evidence is, of necessity, a mainstay in the litigation pro-
cess. Put bluntly, many cases, including very serious cases, could not be tried without expert opinion
evidence. e judicial challenge is to properly control the admissibility of exper t evidence, the manner in
which it is presented and the use the jury makes of t hat evidence.
II. THE LAW REGARDING EXPERT EVIDENCE
A. Expert Evidence: Exception to the Usual Rules
Restricting witnesses to giving testimony as to facts, not opinions, is a cornerstone of the common law
legal system. Non-expert witnesses are invited to recount for the court what they personally observed
with their own senses; they are not allowed to oer what they believe may have happened.
In contrast, an expert witness is granted a special license by the court. Expert witnesses are the only
witnesses permitted by the court to give opinion evidence. ey are — subject to the rules of evidence
— allowed to oer their beliefs and conclusions as substantive evidence. e exception to the rules of
evidence regarding experts and the potential pitfalls are described below.
B. The Admissibility of Expert Evidence in Canadian Law
It is fundamental to the adversarial process that witnesses testify to what they saw, heard, felt, or did.
Using that evidentiary raw material from all the dierent witnesses with dierent testimonies, the trier
of fact (either the judge or the jury) determines the facts.
Expert opinion evidence is dierent. Experts are permitted, precisely because of their expertise, to
lter the facts that have been presented to the court through their professional experience and to render
opinions that “assist the trier of fact in appreciating the signicance of facts in evidence and drawing
the appropriate inferences from them” (Mitchell & Mandhane, 2005). e trier of fact must then decide
whether to accept or reject the expert’s opinion as to the appropriate factual inference. Expert evidence
has the potential to swallow the whole fact-nding function of the court, especially in jury cases, in
which novice triers of fact may be too readily inuenced by an expert’s seeming eminence and by the
seductiveness of her purported scientically grounded opinions. Consequently, expert opinion evidence
must be scrutinized with great care (Justice Doherty of the Court of Appeal in R . v. Abbey, 2009, at p. 353).
e court’s cynicism about psychiatric expertise in particular is historic, and never captured better
than by the following comment by the eminent American jurist, Judge David Bazelon (1974):
Psychiatry, I suppose, is the ultimate wizardry. My experience has shown that in no case is it more dif-
cult to elicit productive and reliable expert testimony than in cases that call on the knowledge and
practice of psychiatry . . . Unfortunately in my experience [psychiatrists] try to limit their testimony to
conclusory st atements couched in psychiat ric terminology.
Similar concerns were expressed by Justice Binnie in R. v. J-L.J. (2000), who described the court’s
role as regards the admission of expert evidence as a “gatekeeper function.” Justice Binnie cautioned that
“undue weight [not be] given to evidence cloaked under the mystique of science.”
Gold’s (2003) concern is that,
faced with an exper t’s impressive credentials and mastery of scientic jargon, which lay jurors do not eas-
ily understand, jurors are likely to overva lue the evidence, giving it more weight than it really deserves, or
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