counsel. Those instructions spoke directly to the manner in which
the jury should address the reliability of the tracing evidence.
[ 19] A proper functional assessment of the adequacy of a jury
instruction, particularly one pertaining to how the jury should
approach and assess certain evidence, must give significant
weight to the position advanced by counsel at trial. To the extent
that the instruction tracks that position, it is likely to properly
serve its functional purpose: see R. v. Polimac,  O.J. No.
1983, 2010 ONCA 346, 254 C.C.C. (3d) 359, at para. 97.
[ 20] Jury instructions are not inadequate or unfair because
they do not include everything that could properly have been said
about certain evidence or certain arguments advanced in respect
of that evidence. It would be a rare charge that could not, upon
critical review in the unhurried calm of the appeal court, be
improved or clarified. The jury instruction must be legally correct
and fair, not perfect: see Calnen, at para. 9; R. v. Huard, 
O.J. No. 4912, 2013 ONCA 650, 302 C.C.C. (3d) 469, at para. 52;
R. v. Newton,  O.J. No. 3107, 2017 ONCA 496, 349 C.C.C.
(3d) 508, at para. 13.
[ 21] Nor is the trial judge required to marshal the evidence and
arguments for either side as counsel might do. Instead, the trial
judge must ensure that the jury appreciates the respective positions of the parties having regard to the evidence and the applicable legal principles. In doing so, the trial judge need not repeat,
much less try to improve upon the way counsel argued the case to
the jury in their closing submissions.
A. The instructions on the tracing evidence
( i) The evidence
[ 22] The evidence relied on by the Crown at trial to trace the
911 call to the phone booth 100 feet from where the appellant
worked was described to some extent in Badgerow #2, at paras.
28-51. The evidence fell into two broad categories. There was evi-
dence from persons who were actually involved in the effort to
trace this 911 call (e.g., Constable Davis). There was also evidence
from persons who had no involvement in the tracing of this par-
ticular call, but who were familiar with the tracing system in
place at the relevant time (e.g., Mr. Johnston). These witnesses
described how the system was designed to allow the police, with
the assistance of Bell employees, to quickly trace a 911 call to a
specific location. The ability to do so accurately was, in some
situations, a matter of life and death.
[ 23] The witnesses involved in the tracing of the 911 call
testified that when the 911 call was received by the police, they