Are you sure that 加拿大禁止使用枪支用于自卫? It seems in Alberta someone used firearm for 自卫, and no charge.
Thank you for clarification.
Self-defence is not something very clear writing by the law, and often it's the decision of the judge, Alberta is definitely more gun friendly than Ontario,also in this case "someone" got it off, but in other 10 cases the person whom try to use firearm to defending their home is facing criminal charges.
Here is one case everyone who interested may want to read:
Man faces jail after protecting home from masked attackers
http://news.nationalpost.com/2011/01/20/man-faces-jail-after-protecting-home-from-masked-attackers/
I find a good post for your question, happy reading:
That depends, but there is a good chance you'd be facing murder charges.
Self defense exceptions to assault are listed in section 34 to 36 of the Criminal Code of Canada. You are permitted to use reasonable force in self defense of your person (not property). However, you must have no choice.
That problem with using a firearm for self defense is that Canadian firearm laws are such that you must go to two separate rooms and unlock both the firearm and then the ammunition and then load the weapon. It is almost impossible to prove that you both knew that the person was there to harm you and then had time to retrieve and load the weapon, or that if you had time to do this but didn't have time to say phone the police, flee your house, etc. If you received the weapon without seeing them... that's typically premeditation.
If it was someone you knew and had threatened you in the past, they were banging on your door and screaming they were going to killed you... and you couldn't realistically flee the building and you called 911, then had time to retrieve and weapon/ammunition while the where breaking the door down or something, and then barricaded yourself in a room, sure.
You can't make any self defense claims for property. Unless the person comes after you... you certainly can't shoot them. Even if they were walking out with your TV set, you can't shoot them. I'll also point out that if you had a firearm (and the time to retrieve and load it), it is pretty hard to claim that someone attacked you with a knife or baseball bat -- unless the guy would absolutely high on drugs, few people are going to rush someone in wait with a rifle or shotgun. If they can see you... they can typically see your weapon and you've certainly had time (since you retrieved and loaded the weapon) to be in a defensible position.
Of course, if they are dead and had a weapon, there typically isn't anyone to contradict your story.