The Admissibility of Expert Evidence
The modern Canadian law on the admissibility of
expert evidence began with the judgment of Sopinka J. in R. v. Mohan,
[1994] 2 S.C.R. 9. But in the last two decades since Mohan was decided
the law on expert evidence has changed significantly.
The test in White Burgess is now the governing
test for the admissibility of expert evidence. It adopts a two-stage approach:
the first stage focuses on threshold requirements of admissibility; the second
stage focuses on the trial judge’s discretionary gatekeeper role. Each stage
has a specific set of criteria.
STAGE
ONE: Threshold Requirements for Admissibility
Expert evidence is admissible when It meets the
threshold requirements of admissibility, which are:
a. The evidence must be logically
relevant;
b. The evidence must be necessary to
assist the trier of fact;
c. The evidence must not be subject
to any other exclusionary rule;
d. The expert must be properly
qualified, which includes the requirement that the expert be willing and able
to fulfil the expert’s duty to the court to provide evidence that is:
i. Impartial,
ii. Independent, and
iii. Unbiased. [FN1]
e. For opinions based on novel or
contested science or science used for a novel purpose, the underlying science
must be reliable for that purpose, and
STAGE
TWO: Gatekeeper Function: Do the Benefits of Admitting the Evidence
Outweigh the Costs?
Expert evidence should not be routinely admitted with
only its weight to be determined by the trier of fact. The unmistakable overall
trend of the jurisprudence has been to tighten the admissibility requirements
and to enhance the judge’s gatekeeping role”.
White
Burgess, at para. 20.
The trial judge, in a gatekeeper role, determines
that the benefits of admitting the evidence outweigh its potential risks,
considering such factors as:
a. Legal relevance,
b. Necessity,
c. Reliability. [FN2]
d. Absence of bias.
In short, if the proposed expert evidence does not
meet the threshold requirements for admissibility it is excluded. If it does
meet the threshold requirements, the trial judge then has a gatekeeper
function. The trial judge must be satisfied that the benefits of admitting the
evidence outweigh the costs of its admission. If the trial judge is so
satisfied then the expert evidence may be admitted; if the trial judge is not
so satisfied the evidence will be excluded even though it has met the threshold
requirements.
R. v. Abbey,
2017 ONCA 640.
Stuart
O’Connell, O’Connell Law Group, www.leadersinlaw.ca
FN1: an expert’s lack of impartiality and
independence and an expert’s bias go to the admissibility of the expert’s
evidence as well as to its weight, if admitted. At the admissibility stage
these qualities are relevant to the threshold requirement of a properly
qualified expert, and they are again relevant at the gatekeeper stage.
FN2: at the gatekeeper stage of admissibility the
reliability of the proposed expert evidence is central to its probative value
and thus to the benefits of admitting it: R.
v. Abbey, 2009 ONCA 624 (CanLII), 97 O.R.
(3d) 330, at para. 87 (Abbey #1).
Comments
Post a Comment