Witness Competence, Compellability and Privilege

• Author: Justice Cameron Gunn/Mona Duckett/Patrick McGuinty
• Pages: 47-63

47

Witness

Competence,

Compellability,

and Privilege

2

I. Competence ............................................. 48

II. Compellability ............................................ 50

III. Privilege ................................................ 51

A. Class Privileges ..................................... 52

B. Case-by-Case Privileges ............................... 59

C. The Accused and Testimonial Privilege .................. 62

Copyright © 2023 Emond Montgomery Publications. All Rights Reserved.

48Part I Witness Preparation

Witnesses are generally competent to testify, compellable by either party, and not

able to withhold information. These concepts—competency, compellability, and

privilege—are related but distinct.

This book is not a text on evidence,1 but the concepts described above are relevant

to counsel seeking to prepare and present a witness or to confront a witness presented

by the opposing party. Whether determining the manner of the presentation of evi-

dence; who will or will not testify; what questions might be asked; or, alternatively,

how to challenge or test the evidence called, counsel has to understand any legal

impediments to the production of evidence. A witness who observed crucial events

may not be able to recount those events because they lack the mental capacity to tes-

tify. Privilege may limit what a witness is able to testify to even if they are competent

and compellable. This chapter will explore, in brief, the potential legal impediments

to witness testimony so that counsel can identify issues and potential solutions.

I. Competence

Competency refers to a person’s legal capacity to give evidence in a court of law.2

The requirement of competence is “to exclude at the outset worthless testimony,

on the ground that the witness lacks the basic capacity to communicate evidence to

the court.”3 Competence is a threshold requirement; that is, a witness may not give

evidence unless they possess the capacity to so. The presumption is that witnesses

are competent.4

One of the principal challenges to competence has been to the mental capacity of

the witness to testify. Section 16 of the Canada Evidence Act5 states that the party who

challenges the mental capacity of a witness bears the burden.6 This challenge is for a

witness 14 years of age or older and is done in the context of an inquiry.

The inquiry requires the court to determine whether (1) the person understands

the nature of an oath or a solemn armation, and (2) is able to communicate the

evidence. If a judge armatively determines these two criteria, then the witness has

capacity and testifies under oath or armation. If, however, the witness is found not

to understand the nature of an oath or a solemn armation, they may still have capac-

ity if the judge finds they are able to communicate the evidence. In such a case, they

testify after promising to tell the truth. If, however, they are not able to communicate

1 For a broader examination of privilege and evidence law in general, see M Gourlay et al, Mod-

ern Criminal Evidence (Toronto: Emond, 2022).

2 R v DAI, 2012 SCC 5 at para 16.

3 R v DAI, 2012 SCC 5 at para 16.

4 R v DAI, 2012 SCC 5 at para 16.

5 Canada Evidence Act, RSC 1985, c C-5.

6 Canada Evidence Act, s 16(5).

Copyright © 2023 Emond Montgomery Publications. All Rights Reserved.