Opinion Evidence

• Author: David M. Paciocco/Lee Stuesser
• Pages: 184-216

Cha pter 6

OPINION EVIDENCE

1. the GeNeraL eXCLUSIONa rY rULe

“In the law of evidence, an opinion means an ‘inference from observed

fa ct .’”1 In our system of trial, it is the neutral, impartial trier of fact

who is to determine what inferences to draw from facts. “A basic tenet

of our law is [therefore] th at the usual witne ss m ay not give opinion

evidence, but testify only to facts within his k nowledge, obser vation

and experience.”2

A major exception applies for exper t witnesses, who are often p er-

mitted to provide conclusions about fact. As w ill be seen, this excep-

tion is allowed because triers of fact lack the experience of the expert

on the matter in question and t herefore require assi stance in k nowing

what to make of the facts.

Since lay w itnesses have no more experti se than the t riers of fact,

there is generally no point in having them provide opinions. Their

views will be super f‌luous, adding nothi ng that t he trier of fact cannot

accomplish itself. In some cases, however, even the evidence of lay wit-

nesses is presented in the form of opinions.

It is more instructive to focus on when opinion evidence will be al-

lowed than to state simply that, as a general exclusionary r ule, opinion

evidence is inadmi ssible.

1 R. v. Collins (2001), 160 C.C.C. (3d) 85 at para. 17 (Ont. C.A.).

2 R. v. D.(D.), [2000] S.C.R. 275 at para. 49.

184

Opinion Evidence 185

2. LaY WItNeSSeS

Lay witnesses may present their relevant obser vations in the form

of opinions where

           

conclusion;

           

able to make;

      

to make the conclusion; and

 

stating facts that are too subtle or complicated to be narrated as

effectively without resort to conclusions.

Even for lay witnesses it is apparent that the general exclusionary rule

disallowing opinion evidence is often not applied. A moment’s ref‌lec-

tion will reveal that the stark d ichotomy between fact and opinion that

is presupposed by the general rule is unrealistic. A s Dickson J. said i n

Graat v. R.: “Except for the sake of convenience there i s little, if any,

vir tue in any distinc tion rest ing on the tenuou s and freq uently fal se an-

tithesis between ‘fact’ and ‘opinion.’ The line between ‘fact’ and ‘opinion’

is not clear.”3 For example, when a witness identif‌ies the driver of the

vehic le by point ing her out i n court, he is stati ng as a fac t that she i s the

driver. Yet, in a rea l sense he is offer ing his opinion that the person in

cour t is th e same p erson wh o was dr iving the veh icle. Num erous ap par-

ent state ment s of fa ct are argu ably no more tha n exp ress ions o f opin ion;

th ings l ike ag e, hei ght, we ight, the id enti f‌icati on of pe ople or thin gs, th e

speed of vehicles, distance, whether someone is happy or angry, all call

for judgment to be made about what has been observed and for con-

clusions to be drawn. Obviously, it is common for witnes ses to testify

about such things. The fact is that lay w itnesses do offer opinions.

We once proceeded on the basis that there was a general exclusion-

ary rule prohibiting lay witnesses from testifying about their opinions,

to which there were numerous particular exceptions allowing for proof

of the kinds of things t hat have just been described. In the important

case of Graat v. R.4 the Supreme Court of Can ada adopted a more gen-

eral, sensible, and less technica l approach. Graat was charged with im-

paired dr iving, and the tri al judge had permitted a series of witnesses

to offer opinion evidence about whether the ability of Mr. Graat to drive

3 (1982), 31 C.R. (3d) 289 at 305 (S.C.C.).

4 Ibid.

THE LAW OF EVIDENCE186

a motor vehicle was impaired. Dick son J. held that it was appropriate

to allow such testi mony, but not because the degree of impairment of

an individual is one of those est ablished, exceptional cases where lay-

persons can offer their opinion. Rather, Dickson J. decided that the evi-

dence was admissible on the more general basis that lay witnesses can

present their obser vations as opinions where they “are merely giving a

compendious statement of facts that are too subtle and too complicated

to be narrated separately and distinctly.”5

To understand t his distinction, attempt to describe the difference

between a vehicle travelling at 40 kilometres an hour and one travelling

at 70 kilometres a n hour wit hout expressing what will clearly b e con-

clusions that capture the series of indescribable and internalized obser-

vations that enable most people to provide fair estimates of speed. Or,

consider the recognition of faces. The compendious statement of fact,

“That is Aunt S ally,” subsumes myriad subtle characteristics observed

and digested by the witness, attributes that could not be communicated

effectively without resort to conclusions.

Except in those common areas where this kind of opinion evidence

is routinely admitted, the admissibility of lay opinion evidence is a mat-

ter of judicial discretion. Based on the reasoning in Graat, a n important

consideration is whether it i s necessary to have the lay w it ness ex press

an opinion. I n exercis ing that discretion, the t rial judge should therefore

assess whether the tr ier of fact is in as good a position as the witness to

form the relevant conclusion. If so, the l ay opinion should not be admit-

ted. In R. v. Walizadah6 the Onta rio Court of Appeal took a more robust

approach, perm itting a police off‌icer to express an opinion about what

surveillance and re-enactment videos showed even though jurors were

in as good a position to make that determination. The Court focused

only on relevance and prejudice in evaluating whether the trial judge

had exercised t he Graa t discretion properly. The specif‌ic decision in the

case is understandable given that per mitting a witness to give thi s kind

of “guided tour” of video ev idence as it is being presented can be us eful

in focusing attention on matters of importance, and given t hat the ap-

peal court, as an appeal court, wa s concerned with the r isk of preju dicial

error. Still, the gener ic focus in t his case on “prejudice” and “relevance”

should not be taken as an appropriate measure for the admissibility of lay

opinion evidence; necessity is ordin arily the central consideration.

It is clear from Graat that in determ ining whether lay opinion evi-

dence is needed, the tria l judge should consider whether, given the na-

5 Ibid. at 310.

6 (2007), 223 C.C.C. (3d) 28 at paras. 44– 46 (Ont. C.A.).