Opinion Evidence

• Author: David M. Paciocco/Lee Stuesser
• Pages: 172-202

172

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

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

1. THE GENERAL EXCLUSIONARY RULE

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

fact.’”1In 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] that the usual witness may not give opinion evidence, but

testify only to facts within his knowledge, observation and experience.”2

A major exception applies for expert witnesses, who are often per-

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

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

on the matter in question and therefore require assistance in knowing

what to make of the facts.

Since lay witnesses have no more expertise than the triers of fact,

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

views will be superfluous, adding nothing that the 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

allowed than to state simply that, as a general exclusionary rule, opin-

ion evidence is inadmissible.

OPINION EVIDENCE

chapter 6

2. LAY WITNESSES

Lay witnesses may present their relevant observations in the form

of opinions where

• they are in a better position than the trier of fact to form the

conclusion;

• the conclusion is one that persons of ordinary experience are

able to make;

• the witness, although not expert, has the experiential capacity

to make the conclusion; and

• the opinions being expressed are merely a compendious mode of

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 dichotomy between fact and opinion that

is presupposed by the general rule is unrealistic. As Dickson J. said in

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

virtue in any distinction resting on the tenuous and frequently false

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

‘opinion’ is not clear.”3For example, when a witness identifies the driv-

er of the vehicle by pointing her out in court, he is stating as a fact that

she is the driver. Yet in a real sense he is offering his opinion that the

person in court is the same person who was driving the vehicle.

Numerous apparent statements of fact are arguably no more than

expressions of opinion; things like age, height, weight, the identifica-

tion of people or things, the speed of vehicles, distance, whether some-

one is happy or angry all call for judgment to be made about what has

been observed and for conclusions to be drawn. Obviously, it is com-

mon for witnesses to testify about such things. The fact is that lay wit-

nesses do offer opinions.

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

sionary rule prohibiting lay witnesses from testifying about their opin-

ions, to which there were numerous particular exceptions allowing for

proof of the kinds of things that have just been described. In the impor-

tant case of Graat v. R.4the Supreme Court of Canada adopted a more

general, sensible, and less technical approach. Graat was charged with

Opinion Evidence 173

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

4Ibid.