Evidence About Credibility and Reliability

AuthorDavid M. Paciocco/Lee Stuesser/Palma Paciocco
Simply because evidence has been admitted does not mean it will be
used. The entire enterpri se of admitting evidence is undert aken to fur-
nish the trier-of-fact with the d ata for decision making. Once evidence
is admitted, the tr ier of fact must decide what to make of it.
A critical determination in discharg ing this obligation is for the
trier of fact to decide what admitted information it will accept and act
upon. There is no presumption that witnesses are credible or that their
testimony is accurate,1 or that evidence that ha s been admitted will be
accepted and utilized. This i s true even of evidence that has gained
admission pursuant to a n admissibility rule that includes a preli minary
reliability ass essment, such as hearsay ev idence admitted under the
principled e xception.2 The trier of fact is free to accept some, all, or
none of the admissible evidence offered by a witne ss.3
In deciding what weight to give testimony, triers of fact should
evaluate that evidence at the end of the case in the context of all other
evidence. When deciding whether to accept testimony as accur ate,
triers of fact wil l consider both “credibility” (the honesty of the witne ss
1 R v Thain (2009), 243 CCC (3d) 230 (Ont CA) at para 32.
2 See the dis cussion in Chapter 4, Section 2.2, “Thre shold Reliability.”
3 R v RR, 2017 ONCA 141 at para 7.
Evidence About Cred ibility and Reliabilit y 593
when relating the testimony) and “reliability” (the accuracy of the testi-
mony given by an honest witness).4 They will do so by consider ing a
range of things, including the character of the witness; the demeanour
of the witness; the condition and capabilities of witness (i.e., things
that may affect their opport unity or capacity to observe); the plausibil-
ity of the testimony (as measured th rough “the probabilities that sur-
round the currently exi sting conditions”);5 the internal and external
consistency of the witness’s evidence; and whether there is supporting
information (in other words, how the testimony “stacks up” to other
available i nformation).6
Much of the data that will be used in examining credibility and
reliability is der ived from primarily mater ial evidence information
that is called to prove or disprove a substantive issue in the case. For
example, a witness’s descr iption of a suspect may not be consistent
with other, more reliable evidence about that suspect, and so t he wit-
ness’s description will b e discounted or rejected. Or, two independent
witnesses may support each other by offering similar testimony. Other
data will come from secondarily material ev idence that is admitted for
the sole purpose of assi sting the trier of fact in as sessing other evi-
dence. For example, a police officer who purports to remember that
the accused smelled of alcohol when arrested for impaired operation a
year before may be asked whether they made a note of thi s observation
at the time, and, if not, how many other impai red operation cases they
have processed in the pa st year. The answers to these questions are not
primarily material evidence, but they may as sist in evaluating the reli-
ability of the police officer’s claim that the accused smelled of alcohol.
Or, a police officer may be asked whether they have been di sciplined
before for providing misleading testimony. An affirmative answer ha s
nothing to do with the primarily materi al issues in the case but may
assist in evaluating the credibility of the officer.
The range of information that may conceivably assist in credibility
and reliability evaluat ion is exceedingly broad, since lea rning anything
about the quality of the witne ss’s memory, attentiveness, experience, or
honesty can help. Yet courts are practical institutions. Time and resour-
ces are not unlimited, and such w ide-ranging inquir ies would be apt to
add little, at great cost. With the exception of the controlled but gener-
ous approach taken to cross-ex amination, the law is t herefore guarded
about the admissibility of secondarily material evidence.
4 See the disc ussion in Chapter 2, Section 4.1, “How Believable I s the Evidence?”
5 Faryna v Chorny, [1952] 2 DLR 354 (BC CA) at 356 [Faryn a].
6 R v S(DD), 2006 NSCA 34 at para 77.
This chapter describ es the rules that control the presentation of sec-
ondarily materi al evidence, including the specia l procedures that may
apply. Most of the rules di scussed here apply to the cross-e xamination
of witnesses c alled by opposing counsel. The special rules th at apply to
evidence about the credibility of a party’s own witnesse s are addressed
in Chapter 11, “Secondary Materiality and Your Own Witness.”
The term “demeanour” is often used, but there is no generally accepted
definition of it. Typically, the term is used in the law of evidence to
describe the comportment of a witness while testif ying insofar a s it
betrays aspect s of the witness’s attitude, knowledge, or emotional state
relevant to their credibility or reliability. However, as some of the deci-
sions about to be discussed reve al, the term “demeanour” is sometimes
used to apply to in-court observat ions made by the trier of fact about the
physical appearance or comportment of someone linked to the event,
who is not necessarily acting as a witness at the t ime the observation
is made, even to support primar ily material in ferences in the case. For
example, the accused may make a threatening gesture in court that
can support the “after-the-fact conduct” inference that the accused is
attempting to hide their complicity by intimidating the witness.7 We
will therefore use the ter m in its broader meaning, to encompass any
observation made in court by t he trier of fact of a witness’s or a party ’s
physical appearance or comportment th at the trier of fact relies upon to
draw inferences in the c ase. Given the theme of the current chapter, the
emphasis in the following d iscussion will be on demeanour evidence
used in evaluating t he credibility or reliability of w itnesses.
Demeanour is not evidence, per se, as it ha s not been admitted at
the proceeding. It has inste ad been observed directly by the trier of fact.
Subject to limits, the trier of fact is nonetheles s entitled to use those
observations when assessing that witness’s testimony.8 For example, if
a witness is co-operative with one side and hostile to another, this may
denote partiality.
However, care should be taken. “It is now acknowledged that
demeanour is of limited value because it can be affected by many fac-
tors including the culture of the w itness, stereotypical attitudes, and
7 See Chapter 2, S ection 3.6, “After-the-Fact Conduct.”
8 R v S(N), [2012] 3 SCR 726.

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