The law in Canada was written so you can't do that under many circumstances. A drunk neighbour who opened the wrong unlocked door and crashed on the wrong couch doesn't deserve to get blasted.

A knife, or similar beweaponed intruder who broke into your home and doesn't leave when they are confronted with residents both deserves to get blasted and the resident will be charged but not convicted.

The key is proportionality to the threat. A drunk mistakenly at the wrong door poses little threat. A 911 call, solid yelling at, and even a push out the door is fine.

The armed intruder who doesn't immediately retreat when confronted takes one step towards you gives a reasonable person a legitimate fear of greivous bodily harm or death and proportional self defense is warranted.

E.g. he had a knife. He adanced towards me. I feared for my life, as most people would under the circumstances and I used the most expiditous means at my disposal to end the imminent threat. (Bat, gun,knife,frozen salmon, table lamp, ming vase, whatever.

If they run, you let them go. It's the police's problem. Easy peasy.

You don't get invited to many parties, do you?