MLJ Volume 36-1.pdf - Robson Hall Faculty of Law

160 MANITOBA LAW JOURNAL|VOLUME 36 ISSUE 1
In sum, undoubtedly there is a need for the trial judge to possess a
residual discretion to exclude any evidence where its probative value is
exceeded by its prejudicial effect. To require that a trial judge be
constrained by statutory rules of admissibility, besides being inconsistent
and arbitrary relating to the equivalent common law rules, would
undermine the trial judge’s fundamental duty to ensure a fair trial process
for all parties, especially the accused. This requires ensuring that the
probative value of evidence received is not outweighed by its
corresponding prejudice.
III. THE GENERAL DISCRETION AT COMMON LAW TO
EXCLUDE CROWN EVIDENCE
The second discretion is the trial judge’s general discretion at
common law to exclude Crown evidence where its prejudicial effect
outweighs its probative value. 74 It owes its existence to Wray, 75 though
It is fair to say, therefore, that not all statutory discretions are created equal: The
scope of the exclusionary discretion incorporated into section 715, in light of the
statements made by the Supreme Court in Potvin, is likely narrower than that
incorporated into either (former) section 715.1 of the Criminal Code or section 12 of
the Canada Evidence Act. Having said that, it paradoxically anticipates excluding some
improperly obtained evidence which is unlike the Supreme Court’s discussions of the
exclusionary discretions incorporated into section 715.1 of the Criminal Code and
section 12 of the Canada Evidence Act, in L (DO) and Corbett, where there is no
mention of either being exercisable against improperly obtained evidence. In this way,
the exclusionary discretion incorporated into section 715 of the Criminal Code may be
viewed as being wider than those discretions to exclude incorporated into (former)
715.1 and section 12 of the Canada Evidence Act.
Despite the Supreme Court’s concern in Potvin that the scope of the statutory
discretion in question be kept within strict bounds, it rejected the Wray formulation
as the weighing exercise to be used in deciding whether the statutory discretion should
be exercised on any given set of facts. The Court criticized it as being too restrictive,
stressing that a trial judge’s emphasis should be on: “The protection of the accused
from unfairness rather than the admission of probative evidence ‘without too much
regard for the fairness of the adjudicative process’ should be the focus of the trial
judge’s concern”: Potvin, supra note 24 at 553.
74
Paciocco & Stuesser, supra note 1 at 38-39, recognize this form of discretion.
75
Admittedly in Wray, the discretion’s existence was only recognized in the obiter
comments of Martland J. Despite this, there is no question as to its existence: see
Boulet v The Queen, [1978] 1 SCR 332, 75 DLR (3d) 223; Paciocco & Steusser, supra