Self-Defence – A Simplified Explanation of the Defence in Canadian Criminal Law

Self-Defence – A Simplified Explanation of the Defence in Canadian Criminal Law

Criminal lawyers, including myself, will at some point in time have a client tell them that their actions amounted to “self-defence”. However, their understanding of what self-defence is can be vary different than what Canadian criminal law says it is. So, what is self-defence?


Self-defence is what is considered a “justification” for what would otherwise be criminal wrongdoing. Section 34 of the Criminal Code of Canada sets out what Parliament has defined as self-defence, and is the starting point to evaluate the defence.

Section 34(1) of the Criminal Code sets out the pre-requisites for this defence:

  • a) that the person believes on reasonable grounds that force is being used against them, or that a threat of force is being made against them;
  • b) that the act that constitutes the alleged offence is committed for the purpose of protecting the defendant from that use or threat of force; and,
  • c) that the act committed is reasonable in the circumstances

Section 34(2) of the Code outlines a list of factors that a court must review in a self-defence assessment, which include the following:

(a) the nature of the force or threat;

(b) the extent to which the use of force was imminent and whether there were other means available to respond to the potential use of force;

(c) the person’s role in the incident;

(d) whether any party to the incident used or threatened to use a weapon;

(e) the size, age, gender and physical capabilities of the parties to the incident;

(f) the nature, duration and history of any relationship between the parties to the incident, including any prior use or threat of force and the nature of that force or threat;

(f.1) any history of interaction or communication between the parties to the incident;

(g) the nature and proportionality of the person’s response to the use or threat of force; and

(h) whether the act committed was in response to a use or threat of force that the person knew was lawful.


It’s important to note that the accused person is not required to prove that they acted in self-defence. Once an err of reality is raised in the evidence that the accused acted in self-defence, then it becomes the Crown’s burden to disprove the defence beyond a reasonable doubt.

An err of reality is a low threshold to meet, and it requires that the Judge or Jury be satisfied that there is at least some evidence upon which a reasonable jury could find that self-defence applies.

The evidence is not weighed at all at this stage of the analysis.


The common law has significantly shaped the defence of self-defence over the years, creating key legal precepts that Courts must take into account when evaluating whether an accused’s actions are justified by way of the defence.

For example, a long standing principle in this context is that a person defending him/herself against an attack cannot be expected to weigh to a nicety the exact measure of defensive action. In other words, Courts have ruled that it is difficult for individuals to make very calculated and precise decisions when they are faced with high risk and high pressure situations.

Another principle is that it is the force used that must be the focus of the assessment rather than the consequences of the force.


A very simple way to understand the defence is that it arises when someone is being attacked, or under the threat of attack, and responds physically to that attack (or threat) for the sole purpose of defending or protecting themselves. The response chosen must be reasonable in the circumstances.

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