I live in the States, and from my understanding of the laws of the state that I live in(Georgia), I can use deadly force to repel intruders as long as the following conditions are met:

1.) They break into my house, and are physically located in my house.
2.) They appear to have a weapon or claim they have a weapon.

The basis for these rules is that a person standing on my lawn is not considered by their very presence there to be a deadly threat. Even if they do break into my house, they have to claim they have a weapon or appear to have a weapon - "appear" is where things get a bit sketchy.

If they hold their hand in a way that it looks like they're holding a gun, I can shoot them, but if I don't shoot and kill them(for example, I shoot them in the arm), they can sue me and are almost guaranteed to win the lawsuit. If I shoot them and they don't appear to have a weapon, what's to stop me from lying? Ghosts don't give testimony. I suppose ballistics could track if I shot him running away or from a face down position, but a spur-of-the-moment, "caught him coming in the front door" situation? Unlikely.

Not to mention that most people are a bit wary of using guns, especially on humans. Even a large majority of non-violent criminals(petty theft and the like) have admitted to being more nervous when guns are involved in a crime. With your nerves tied up in knots, a five-pound pull on the trigger feels more like a hair-trigger.

I believe the answer is no. According to Canadian law: Every one who is unlawfully assaulted without having provoked the assault is justified in repelling force by force if the force he uses is not intended to cause death or grievous bodily harm and is no more than is necessary to enable him to defend himself.

Call a local lawyer and ask this question. This is too important to leave to semi-anonymous people on the internet. BTW, post his response here.