Here in Canada, lethal force is legal so long as it meets the definition of 'reasonable force'. IOW, if an old lady starts swinging her handbag at you in the mall, you are required to make every reasonable effort to leave the scene and let law enforcement handle it. OTOH, if someone(s) breaks into your house, and you have reasonable grounds to believe that they mean you (or others in the house) harm, you are allowed to use the necessary level of force, up to, and including lethal force, to defend yourself. This derives from the English common law principle, that 'a man's home is his castle'. You do not have to flee your own home.
If you shoot an intruder, the police will probably arrest and charge you, but once the authorities are reasonably sure that the shooting victim is in fact, an intruder, the charges will be dropped. Of course, the 'reasonable force' defence does not apply if the intruder(s) are attempting to flee...
Two years ago, my friend's 19 yr old grandson was stabbed and died while violently breaking (with 3 or 4 others)into a house and threatening the occupants. They were attempting to forcibly retrieve a 14 yr old girl that had run away with her boyfriend...
The killer was charged, but never brought to trial. And IMO, that is exactly how it should be. All this misery could have been avoided by letting the authorities handle it.
As for myself, my home has been robbed (while we were away) and because I don't have to worry about children, I have a 12 ga. Ithaca pump and a box of #4 birdshot in the bedroom closet. And if I ever feel threatened, I have no moral qualms about using it. "Better to be tried by twelve than to be carried by six"...
We've had a spate of vicious home invasions, mainly targeting the elderly, here (Nova Scotia) recently, including one where a 70 yr old man was beaten to death by a gang of thugs, so I have little sympathy for anyone who gets wasted while breaking into homes. Good for that little girl, and I hope she will realize that she did what had to be done.
JL