The laws of Canada may be similar to those found here in NT Australia. Here, the owner/occupier of a residence has the legal right to evict a trespasser, by using reasonable force if necesary. Similarly, there is a legal right to defencive conduct, where, if you are defending yourself (or others) and also for removal of trespassers.
The level of force used has to be reasonable and justified, under the current law, it would be fine for an owner/occupier to take a baseball bat to someone they find in their house, just so long as they didn't cause death or serious harm while wielding the bat.
The laws give you the right to defend yourself and get unwanted people out of your house, the laws are not going to go so far as to say that people have a justification for killing.
Where someone is killed by an owner/occupier, I would be surprised to see them convicted of murder, I reckon any savvy lawyer type would be able to water the charge down to manslaughter due to the dubious nature of intent. (didn't want to kill him, just wanted him out of my house.....)