Edited by Lannis on April 4, 2018, 10:35 pm
Just answering the question "as is", in most states it's the 'Castle Doctrine' here.
Your home is your castle. You are allowed to assume that anyone inside your home without your permission is there to harm you, and you're allowed to use any means necessary, including deadly force, to stop them from harming you. You can't set tripwires and deadly man-traps while you're out, but someone comes in while you're there, you can shoot, no questions asked.
If you call 911 and say "Some dude came into my house, don't know what he was doing here, I shot/stabbed/clubbed him ... " there will be some investigating to make sure it's not a wife's former boyfriend and you decoyed him into the house to shoot him, but in the absence of something obvious like that, the homeowner will get a handshake from the police, because 99 times out of 100, the dead body on the floor is already WELL known to them.
Hard to feel sorry for the intruder; amazingly enough, I've NEVER accidentally broken into someone's house thinking that it was mine ... ! Bet no one else you know has either ...