In Canada, obtaining a verdict of self defense with a firearm is extremely difficult. You basically have to prove that you did everything in your power to diffuse the problem before turning to a firearm, you contacted the police, your life was in immediate danger, you somehow managed to unlock and load your firearm while still being in danger, and that if you hadn't done what you did you'd be dead.
Same, same. Here it is either "necessary defense" (when you defend yourself against an attacker) or "extreme emergency" (covers all the other situations of using firearms).