( iii) The admissibility of demeanour evidence and the
jury instruction on that evidence
 The jury heard a great deal of evidence about how the
appellant acted or reacted on various occasions on the night of
the murder and in the days following. That evidence included
testimony from various witnesses that the appellant seemed
“normal” or, to the contrary, “unusual”. The jury also heard evidence that some of the things the appellant did and said seemed
to others to be contrived or rehearsed.
 Evidence describing the demeanour of an accused when
he did or said something can be admissible. The demeanour may
be sufficiently unambiguous to give it probative value, or it may
be an integral part of the witness’ description of the relevant
event: R. v. Trotta,  O.J. No. 4366, 190 C.C.C. (3d) 199
(C.A.), at para. 41.
 Demeanour evidence is, however, often of little or no probative value. There is also a real risk that a jury might give too
much weight to demeanour evidence unless clearly cautioned
that the evidence can be misleading and often provides little or
no real insight into a person’s state of mind, or the reasons
for that person’s actions: R. v. Levert,  O.J. No. 3907,
159 C.C.C. (3d) 71 (C.A.), at para. 27; R. v. Wall (2005), 77 O.R.
(3d) 784,  O.J. No. 5095 (C.A.), at paras. 49-50.
 At the new trial, the trial judge may conclude that some of
the demeanour evidence has virtually no probative value and
should not be admitted. For example, if a witness describes the
appellant as acting “unusually”, but does not know the appellant
and cannot articulate any basis upon which the witness formed
his or her opinion about the appellant’s behaviour, the trial
judge may well conclude that the witness’ opinion about the
appellant’s behaviour has no probative value and should not
 To the extent that demeanour evidence is properly before
the jury, the trial judge must be careful to instruct the jury about
the risks inherent in drawing inferences from a witness’ description of someone else’s demeanour: see Wall, at paras. 49-50.
( iv) The absence of any limiting instruction in respect of
Officer Miller’s testimony
 The defence claimed that the police quickly focused on
the appellant as the perpetrator of the murder to the exclusion
of all other suspects. To support this “tunnel vision” theory,
defence counsel cross-examined Detective Miller with a view to