Most of these urban legends come from a few misunderstood instances. Much like the infamous McDonald's coffee case (where the victim had 3rd degree burns including the fabric of her pants literally fused to her skin
because McDonald's kept their coffee significantly hotter than industry standard so it would stay "fresher" longer...and she initially only asked them to repay her medical bills, which were hundreds of thousands of dollars, and only when McDonald's refused did she sue...and she was actually awarded more than she requested in damages due to McDonald's negligence...but still the popular conception is "of course coffee is hot, dummy!")...
One of the big things that happens is when someone intentionally booby traps their land to cause injury to trespassers/intruders (by booby trap I mean setting traps that people can't see but will be injured by). You can't do that--and honestly, for good reason. I mean, what if EMTs are called because you're having a heart attack and get hit by your booby traps? However, at least in my state, a dog biting an intruder does not fall under that category (although, in said EMT scenario, you may have to wait for animal control to respond before they'll come in and save you). If someone is breaking into your house and the dog bites them, it will be ruled a justified bite. If a kid is taking a short cut across your unfenced lot and your dog bites them, you might get in trouble, but the bite will still be investigated and depending on the circumstances it may or may not be ruled "justified."
A dog biting the plumber you left the door open for will probably cause you trouble, even though from the dog's perspective it's all the same--but it's your responsibility to control your dog at all times and the dog shouldn't have been loose. A dog biting an unauthorized intruder (say, burglar) is probably not going to cause you trouble.
That said, anyone can file a lawsuit, which is the other big thing that gets people. A burglar could sprain his ankle kicking in your door and sue you; that doesn't mean he'd win. That's the US justice system, and why we have homeowner's and renter's insurance, since you do have to pay to defend yourself. Sensationalist news outlets will pick up on a suit that is filed, and conveniently not report when it is lost or dismissed.
So in short, I don't worry about my dogs potentially biting a burglar.
same advice I've been told by every police officer and attorney that I know.
Well, that and NEVER fire a warning shot. Always shoot to kill. Has nothing to do with not wanting to be sued, really. It's not wanting to be arrested! If you don't shoot to kill, the argument can be made that you really weren't in fear of your life since you just wanted to "scare him away" I'll take my chances that his family will try to sue over defending myself against attempted murder charges any day.
ETA: lol didn't realize until I read a post by me that this was an old thread! oops
The way I was always taught, warning shots are dangerous. Where are you shooting? If you live in a remotely residential area, that bullet is going to land somewhere and it could land in an innocent neighbor's head, or ricochet if shot into the floor. Plus yes, you only pull your weapon when you are in fear of your life.
As far as shoot to kill, it's more like shoot the largest mass so you have most chance of making your shot. Head shots, knee shots, whatever are difficult for even skilled marksmen in the heat of the moment. You shoot the torso; it has a good chance of being fatal but that's not necessarily why you do it--all that matters is stopping the person.