You absolutely CAN defend yourself with a gun in Canada.
The Criminal Code, section 35, defines our rights with respect to defending our property. If we believe, on reasonable grounds, that someone is unlawfully entering our property or about to damage it, we can take reasonable actions to prevent the person from entering our property, prevent them from stealing or damaging our property, and to physically remove them from our property. This means grabbing an intruder or burglar and knocking them down would be a reasonable defence, but shooting them would be deemed unreasonable.
In Canada, the use of firearms for defence of self or property is generally prohibited by law.
The Criminal Code, section 34, deals with our right to lawfully defend ourselves (or our loved ones). Under the law, we can defend ourselves with reasonable force if we are physically attacked or if we have good reason to believe that a person is going to use force against us or against another person, such as a family member. However, our actions must be solely for the purpose of defending or protecting ourselves from harm. For example, if we continue to strike someone who is no longer a threat, then that action would not be perceived as lawful. As in the defence of property, a person can legally defend themselves by actions that are reasonable in the circumstances. Some of the factors that the courts will use to judge if you used reasonable force in defending yourself are:
-What was the nature of the threat or force?
-How imminent was the threat to our safety (i.e. is the danger just about to happen or do we have time to avoid a physical altercation)?
-Did we have other options to respond to the threat, other than physical force?
-Did either my attacker or I use a weapon?
-What was the relative size, age, gender and strength of the two parties involved in the incident?
-Do the parties involved have a prior relationship or a history of disagreements or fighting?
-Was my response to the threat or attack relatively proportionate to the attacker’s action?
-Was the threat or use of threat against me authorized by the law? (i.e. if police are lawfully entering your property or detaining you, you cannot use force to defend yourself against them.)