Introduction: Basic Concepts in the Law of Evidence

• Author: Matthew Gourlay/Brock Jones/Jill D. Makepeace/Glen Crisp/Renee Pomerance
• Pages: 1-20

CHAPTER 1

INTRODUCTION: BASIC CONCEPTS IN

THELAWOF EVIDENCE

I. What Is the Law of Evidence and What Is It For?......................... 

II. The Sources of Evidence Law......................................... 

III. The Basic Rule of Evidence........................................... 

IV. The Objectives of Evidence Law ...................................... 

V. Defining Relevance and Materiality .................................... 

VI. Understanding Probative Value and PrejudicialEffect ................... 

A. Probative Value ................................................ 

B. Prejudicial Effect ............................................... 

VII. Burdens and Standards of Proof ..................................... 

A. The Burden of Proof on the Crown ............................... 

B. Burdens of Proof on the Defence ................................. 

1

Copyright © 2022 Emond Montgomery Publications. All Rights Reserved.

I. WHAT IS THE LAW OF EVIDENCE AND WHAT IS IT FOR?

At its core, a criminal trial is all about ans wering a single question: has the Crown proven

the accused’s guilt beyond a reasonable do ubt? This almost invariably implies a dispute

over the “who,” “what,” “when,” “how,” or “why” of whatever is alleged to have taken

place.1 If the centra l facts are not in dispute, the charge will be resolved by a guilty plea

or a withdrawal. Where those fa cts are in contention, a trial will usually take place. Evi-

dence is the material put before the court to reso lve the factual disputes that have given

rise to a trial.2

The law of evidence is a set of rules and p rinciples that answer two principal questio ns:

• What evidence can b e considered by the trier of fact?

• Once the eviden ce is admitted, what can th e trier of fact do with it?

One plausible answer to both questions is “anything”—in which case the need for

a law of evidence would be reduced or eliminated. Indeed, the existence of a discrete

body of law governing the admission and use of evidence is not an inevitability. Ben-

tham famously advocated the adm ission of all relevant evidence, arguing that the only

way to reach the truth is to “see everything that is to be seen; hear everybody who is

likely to know anything about the matter: hear everybody, but most attentively of all,

and first of all, those who are likely to kn ow most about it—the parties.”3

If all relevant evidence were admissible, we could dispense with much of what

we currently know as the law of evidence. And indeed, much of the rest of the world

manages without the complex web of exclusionary rules that our common law has

developed. The noted eviden ce scholar Thayer long ago observed:

At once, when a man raise s his eyes from the common-law system of evid ence, and looks

at foreign methods, h e is struck with the fact that our system is ra dically peculiar. Here, a

great mass of evidentia l matter, logically important and p robative, is shut out from the view

of the judicial tribuna ls by an imperative rule, while the same mat ter is not thus excluded

anywhere else . English-speaking countries have what we call a “ Law of Evidence;” but no

other country has it; we a lone have generated and evolved this large , elaborate, and dif-

ficult doctrine.4

But, for better or worse, this “large, elaborate, and difficult doctrine” is our own. In

recent decades, to be sure, the Supreme Court of Canada has made strides toward

1 The only exception w ould be where the fact s are undisputed and th e only contentious issue is w hether the

undisputed fac ts disclose the offence ch arged.

2 If the accused pleads guilt y, the need for evidence is a lmost invariably di spensed with and a fin ding of guilt

is made on the admi tted facts. Of course, ev idence may subsequently be le d at the sentencing hearing.

However, the focus of this b ook is on evidence led at trial to reso lve the question of guilt or in nocence.

3 Jeremy Bentham , “Rationale of Judicial Eviden ce” in The Works of Jeremy Bentham, vol 7 (Ed inburgh:

William Tait, 1843) at 599.

4 James Bradley Thaye r, A Preliminary Treatise on Evidence at the Comm on Law (Boston: Little, Brown,

1898) at 1-2. It is a mistake to thin k that Continental (Europe an) systems do not possess th eir own bodies

of evidence law, inclu ding rules of privilege and ru les excluding illegally obtain ed evidence. The most

salient difference is that Continental courts generally do not exclude otherwise probative evidence on the

basis of concerns th at it may be misused: Mirjan R Da maska, Evidence Law Adrift (New Haven, Conn: Yale

University Pr ess, 1997) at 14-17. Common law court s do this all the time.

2MODERN CRIMINAL EVIDENCE

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