[JohnJ]

I would say it's on a dog to dog basis.
I had a large Weimaraner that would have undoubtedly killed an intruder. I also had a Pit that would have smothered an intruder with kisses.
Bubba is still young, but as of now he'll stand in the doorway, bark, hackles up and block the entrance unless I go to the door and let them in. He hasn't snapped at anybody but nobody has attempted to push their way in either.
When it's a friend who's been over or a neighbor letting themselves in, he'll bark at first and then starts the kisses.

 

[JohnJ]

If your dog bites someone who casually walks in your door, then guess what, you are getting sued and your dog put down.

Not always the case but I know what you mean.
My family Weimaraner bit our neighbor who noticed our front door was partially open and tried to close it. We were on vacation and came home to a blood trail leading from our front door and down to the neighbors house.

She saw it as her mistake and that the dog was only doing a job.
I could see being sued and the dog put down in certain situations, but an uninvited person walking in the front door without notice?? If only there were a lawyer on this board.......#-o