Expert Opinion Evidence: The Middle Way
| Author | Adam Wilson |
| DOI | 10.1350/jcla.2009.73.5.592 |
| Published date | 01 October 2009 |
| Date | 01 October 2009 |
| Subject Matter | Article |
Expert Opinion Evidence: The
Middle Way
Adam Wilson*
Abstract This article assesses the admissibility of expert testimony and
suggests that generic principles for admission may, taken in isolation, be
more inclined to mislead than assist. Instead, it is preferable to consider
each case on an individual basis. This is the current judicial response. The
judicial response, whilst broadly correct in approach, may benefit in terms
of implementation by greater precision of definition. Judges may benefit
from guidance provided by working parties outside the courtroom. A
middle path is suggested charting a path between laissez-faire admission,
on the one hand, and a call for pervasive principles of admission, on the
other.
Keywords Criminal evidence; Expert opinion testimony; Admiss-
ibility of expert evidence
There is an adage that justice must be done and be seen to be done.1
Expert testimony arguably serves a function on both sides of this equa-
tion ascertaining factual truth whilst, simultaneously, allowing courts to
bask in the perceived infallibility of forensic science. This double benefit
may, however, become short lived if forensic science is admitted too
lightly and, over time, becomes discredited. High-profile miscarriages of
justice make this latter concern not entirely fanciful.2
This article assesses the law pertaining to admissibility of expert
testimony. These rules may be divided into two related, but distinct,
questions. First, the expert must be received by the court.3Secondly, the
discipline must be adjudged worthy of admission.4There are two poss-
ible responses to these questions. The first is to seek principles of generic
application. This article suggests that articulating generic principles for
admission may, taken in isolation, be more inclined to mislead than
assist. The second is to consider each discipline, and expert, on their
merits on a case-by-case basis. This is often the judicial response.5The
judicial response, whilst broadly correct in approach, may benefit in
terms of implementation by greater precision of definition and more
detailed evaluation. Judges may benefit from guidance provided by
working parties outside the courtroom. A middle path is suggested
charting a path between a laissez-faire approach to admission, on one
* Senior Lecturer in Law Sheffield Hallam University; e-mail: A.J.Wilson@shu.ac.uk.
1 One may add the modern mantra that justice must be done cheaply.
2 There is a Law Commission consultation: see Law Commission, The Admissibility of
Expert Evidence in Criminal Proceedings in England and Wales, Law Com. CP 190,
published 7 April 2009, available at http://www.lawcom.gov.uk/current_consultations.
htm, accessed 3 August 2009.
3R v Robb [1991] 93 Cr App R 161 at 164.
4 Ibid.
5R v Luttrell [2004] 2 Cr App R 31 at [37].
430 The Journal of Criminal Law (2009) 73 JCL 430–450
doi:10.1350/jcla.2009.73.5.592
hand, and an onerous call to arms for all-pervading principles of admis-
sion, on the other. Equally, assessing expert testimony is neither left
solely in the hands of the judiciary nor completely removed from
them.
Admission of the expert
Peritus
The test for admissibility, in relation to the expert, was defined in R v
Silverlock:6
The question is, is he peritus? Is he skilled? Has he an adequate knowledge?
. . . There is no decision which requires that the evidence . . . be excluded
because his experience has not been gained in the way of his business.
This case concerned admission of handwriting. The noun ‘peritus’,
however, imports a theological aspect wholly inappropriate for discus-
sions on handwriting analysis.7One explanation may be that the word
‘peritus’ is associated with the Latin ‘expertus’.8The court may have
intended this latter definition. The circularity of this definition would
equally add little as it would, in effect, provide that an expert is expert.
The quality eliciting expertise remains hidden.
Study and experience
The case of R v Robb,9later, added the gloss:
Whether study and experience will give a witness’s opinion an authority
which the opinion of one not so qualified will lack, and (if so) whether the
witness in question is peritus. (emphasis added)
The concepts of ‘study’ and ‘experience’ are not without difficulty.
Turning initially to ‘study’, there are issues in relation to definition.
Study
Academic qualifications
Academic qualifications may suffice for study. It was stated in Robb:10
A defendant cannot fairly be asked to meet evidence of opinion given by a
quack, a charlatan or an enthusiastic amateur. But we do not regard Dr.
Baldwin as falling anywhere near these categories. He was entitled to be
regarded as . . . well qualified by academic training and practical experience.
(emphasis added)
Whilst academic training is not synonymous with academic qualifica-
tions Bingham LJ specifically noted Dr Baldwin’s BA, MA and PhD.11
6 [1894] 2 QB 766 at 771.
7 The Oxford Dictionary of English, 2nd edn at 1310 defines ‘peritus’ as ‘a theological
adviser or consultant to a council of the Roman Catholic Church’.
8 Ibid.
9R v Robb [1991] 93 Cr App R 161 at 165.
10 Ibid. at 166.
11 Ibid. at 165.
Expert Opinion Evidence: The Middle Way
431
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