Self-Defence
Self-defence is the criminal defence that justifies the use of force where the accused acted in response to a threat — to defend themselves, another person, or property in some configurations. The Criminal Code's self-defence provisions were comprehensively restructured by the Citizen's Arrest and Self-Defence Act, in force since 2013, and are now consolidated in section 34. The defence applies to virtually all assault-related offences, from simple assault through aggravated assault and, in extreme cases, homicide.
Mass Tsang's assault lawyers handle self-defence cases across the GTA. For more, see our blog post on self-defence law in Canada.
The three elements
Section 34 requires the Crown to disprove three elements once the defence has been raised with an air of reality: (1) the accused believed on reasonable grounds that force or a threat of force was being used or made against them or another person; (2) the act constituting the offence was committed for the purpose of defending or protecting themselves or the other person; and (3) the act committed was reasonable in the circumstances. If the Crown cannot disprove any of these elements beyond a reasonable doubt, the defence succeeds.
Reasonableness factors
Section 34(2) lists factors the court considers when assessing reasonableness, including: the nature of the force or threat; the imminence of the threat and other means available to respond; the role of either party in any prior incident; whether the accused or other party used or threatened to use a weapon; the size, age, gender, and physical capabilities of the parties; the nature, history, and relationship between the parties; the nature and proportionality of the response; and whether the act was a response to a known use or threat of force. The list is not exhaustive.
Initial aggressor and proportionality
The old common-law rules about initial aggressors and proportional response have been folded into the section 34 reasonableness analysis. A person who started the confrontation is not automatically barred from claiming self-defence, but their role weighs heavily against them. Disproportionate response — using a knife against a slap, for example — is also a major factor. The 2012 reforms moved the analysis from rigid rules to flexible contextual judgment.
Defence of property
Section 35 provides a parallel defence for the protection of property. The elements are similar but adapted to the property context. Self-defence and defence of property frequently overlap — an intruder being expelled from a home, for example, may engage both. The reforms aimed to simplify and unify the previously fragmented defences.
Air of reality threshold
Before self-defence is left to the trier of fact, the defence must demonstrate an air of reality — some evidence in the record on which a properly instructed jury, acting reasonably, could acquit. Once that threshold is met, the Crown must disprove the defence beyond a reasonable doubt. The air-of-reality threshold is low, but not nothing.
Related glossary terms
