From Criminal Law Notebook
This page was last substantively updated or reviewed January 2019. (Rev. # 84130)

General Principles

An accused person can escape criminal liability for an offence that they could otherwise be convicted for by sufficiently proving the existence of one or more established defences.

Defences are often categorized as follows:

  • Justification: a justifiable act is one that makes out the offence but is justified by the external circumstances in which the act was committed. (e.g. self-defence)
  • Excuse: a criminal act is excused where the accused would have committed an undesirable criminal offence, the punishment for the offence would be morally inappropriate due to the extenuating circumstances. (eg. offences due to mental infirmities, duress). Defence such as necessity and duress are excuses since they are founded in their moral involuntariness.[1]
  • Affirmative Defence: a defence that, if proven, will eliminate liability despite all the elements of the offence having been made out
  • Negating Defence: a defence that negates one or more of the essential elements of the prosecution's case.

An affirmative defence is generally considered a type of justification defence.[2]

Appellate Review

Whether the judge correctly put a defence to a jury is a question of law and reviewable on a standard of correctness.[3]

  1. R v Ryan, 2013 SCC 3 (CanLII), [2013] 1 SCR 14, per LeBel and Cromwell JJ, at para 23
  2. R v Keegstra, 1994 ABCA 293 (CanLII), 92 CCC (3d) 505, per Harradence JA, at para 18 appealed to [1996] 1 SCR 458
  3. R v Tran, 2010 SCC 58 (CanLII), [2010] 3 SCR 350, per Charron J at 40

Common Law

Section 8(3) of the Criminal Code addresses the common law authority to define available defences: {{quotation2| 8
[omitted (1) and (2)]

Common law principles continued

(3) Every rule and principle of the common law that renders any circumstance a justification or excuse for an act or a defence to a charge continues in force and applies in respect of proceedings for an offence under this Act or any other Act of Parliament except in so far as they are altered by or are inconsistent with this Act or any other Act of Parliament.

[[List of Criminal Code Amendments|R.S., 1985, c. C-46, s. 8; 1993, c. 28, s. 78; 2002, c. 7, s. 138. ]]

Section 8(3) does not restrict the power of the court to "enlarge" the common law by recognizing new defences.[1]

  1. Kirzner v R, 1977 CanLII 38 (SCC), [1978] 2 SCR 487, per Laskin CJ ("I do not think that s. 7(3) should be regarded as having frozen the power of the Courts to enlarge the content of the common law by way of recognizing new defences, as they may think proper according to circumstances that they consider may call for further control of prosecutorial behaviour or of judicial proceedings.")
    R v Jobidon, 1991 CanLII 77 (SCC), [1991] 2 SCR 714, per Gonthier J ("[s. 8(3)] ...authorizes the courts to look to preexisting common law rules and principles to give meaning to, and explain the outlines and boundaries of an existing defence or justification, indicating where they will not be recognized as legally effective -- provided of course that there is no clear language in the Code which indicates that the Code has displaced the common law.")


Excuses and justifications do not "negative the mens rea rather they operate by justifying or excusing what would otherwise be criminal conduct."[1] It is a "concessions of human frailty" when face with an untenable choice.[2] Such conduct is not always morally blameless, however.[3]

Provisions of the Code can specify an offence as being made out "without reasonable excuse."[4] This part of the Codes lies "outside of the elements of the offence."[5]

  1. R v Hibbert, 1995 CanLII 110 (SCC), [1995] 2 SCR 973 (SCC), per Lamer CJ, at para 47
    R v Ryan, 2013 SCC 3 (CanLII), [2013] 1 SCR 14, per LeBel and Cromwell JJ, at para 23 - An excuse does not negate the wrongfulness of the act.
  2. Ryan, ibid., at para 23 citing R v Ruzic, 2001 SCC 24 (CanLII), [2001] 1 SCR 687, per Lebel J
  3. Ryan, ibid., at para 23
  4. e.g. Refusal (Offence)
  5. R v Greenshields, 2014 ONCJ 35 (CanLII), per Duncan J, at para 16
    R v Taraschuk, 1975 CanLII 37 (SCC), [1977] 1 SCR 385, per Laskin CJ
    see also Intention

Burden to Prove Excuse

See also: Burden of Proof

Under s. 794, the Code states that the burden is on the defendant to prove an exception or excuse:

No need to negative exception, etc.

794 (1) No exception, exemption, proviso, excuse or qualification prescribed by law is required to be set out or negatived, as the case may be, in an information.

(2) [Repealed, 2018, c. 29, s. 68]

R.S., 1985, c. C-46, s. 794; 2018, c. 29, s. 68.
R.S., c. C-34, s. 730.


Note up: 794(1)

The shifted burden found in s. 794(2)--as it existed before December 13, 2018--has been interpreted as applying only to the "narrow circumstances, usually regulatory offences, where a status in law has been conferred upon the accused who would otherwise be culpable."[1] This section has no application to offences in s. 335(1.1)[2] It has been applied in charges of refusal to give a breath sample under s. 254(5).[3] As well as s. 145(3) breaches of conditions.[4]

The section has been found to apply in regulatory provincial offences.[5]

  1. R v PH, 2000 CanLII 5063 (ON CA), 143 CCC (3d) 223, per Finlayson JA, at para 14
  2. PH, ibid., at para 14
  3. R v Goleski, 2015 SCC 6 (CanLII), 320 CCC (3d) 433, per curiam
  4. R v AMY, 2017 NSSC 99 (CanLII), per Rosinski J
    cf. R v Truong, 2008 BCSC 1151 (CanLII), 235 CCC (3d) 547, per Smart J, at para 24
  5. e.g. R v DMH, 1991 CanLII 4553 (NS CA), (1991) 109 NSR (2d) 322 (CA), per Hart JA
    R v TG, 1998 CanLII 11 (NS CA), NSR (2d) 265 (CA), per Chipman JA, at paras 15 to 19

Raising a Defence

Rejected or Prohibited Defences

Ignorance of the Law

By s. 19, the ignorance of the law is no defence. However, there are limited exceptions where the underlying belief is due to officially induced error or mistake of fact.

Ignorance of the law

19 Ignorance of the law by a person who commits an offence is not an excuse for committing that offence.
R.S., c. C-34, s. 19.


Note up: 19

An accused commits a "mistake in law" where he "erroneously believes that his voluntary action does not contravene a legal order or who is mistaken about the application of a legal order."[1]

Suicide Pact

There is no defence in the common law that can reduce murder to manslaughter where the unlawful death was pursuant to a suicide pact.[2]The existence of a suicide pact would only be relevant towards a defence "not criminally responsible due to mental disorder defence."[3]

  1. R v Allaby, 2017 SKCA 25 (CanLII), 353 CCC (3d) 476, per Ottenbreit JA (3:0) , at para 42
  2. R v Dobson, 2018 ONCA 589 (CanLII), 48 CR (7th) 410, per Doherty JA
  3. Dobson, ibid., at para 42

Types of Defences

Case Digests

See Also