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136 MANITOBA LAW JOURNAL |VOLUME 35 NUMBER 1
The Court of Appeal decided that the trial judge need only find that the
Crown expert had sufficient skill, knowledge, or expertise to provide an opinion
that would be helpful to the trier of fact in reaching a just decision. Once the
basic methodology was deemed admissible, it was the role of the jury to determine
if this particular application of the methodology was appropriate. 143 The standard
for qualification of an expert was found to be on the balance of probabilities even
when novel science was in question. 144 Furthermore, Finlayson JA held that no
special burden should be placed on DNA evidence in that it was only another
form of identification evidence, analogous to other commonly used forms of
identification such as fingerprints and dental impressions. 145
The appellant also argued that whether or not the DNA evidence was
deemed to be admissible, there was significant danger of the jury interpreting the
probability estimates provided by the DNA expert witness as representing the
probability of the appellant’s innocence. 146 He also argued that DNA evidence
deserved a special hearing and a higher standard of proof, using Mohan’s
conclusion that as expert testimony approaches the ultimate issue it deserves
greater scrutiny. 147 The Court found that the danger of this “mystic infallibility” of
DNA evidence was amply handled by the testimony of defence experts as to its
limitations and possible problems and through appropriate jury instruction. 148
The Court of Appeal generally accepted the trial judge’s shift of most of the
scientific analysis to the trier of fact. 149 The admissibility inquiry at the voir dire is
thus a procedure with a relatively low threshold requirement. This requirement in
this case was largely met by the admission on the part of the defence of the
general admissibility of DNA evidence generally as well as by the credentials of
Ms. Newall. The jury instructions become vital, and after an analysis of the jury
instruction Finlayson JA set out the requirements for an appropriate jury
instruction where DNA evidence is proffered:
At the conclusion of the evidence, the trial judge in his instruction should advise the jury
in the normal way as to the limits of the expert evidence and the use to which it can be put.
Additionally, in the case of DNA evidence, he or she would be well advised to instruct the
jury not to be overwhelmed by the aura of scientific infallibility associated with scientific
evidence. The trial judge should tell them to use their common sense in their assessment of
all of the evidence on the DNA issue and determine if it is reliable and valid as a piece of
circumstantial evidence. 150
143
144
145
146
147
148
149
150
Ibid at para 32.
Ibid at paras 45-46.
Ibid at para 47.
Ibid at para 58.
Ibid at para 48.
Ibid at para 55-57.
Ibid at para 56.
Ibid at para 65.