I had a dog that bit a person in the face (unfortunately for both of them, they leaned over to kiss the dog and dog was not in favor). My dog was on a 4 foot leash. I always had her on leash when people were around because she'd growled and showed teeth to people, and bit a running person in the past. I was completely unprepared for the person's move. They had ultimately I think 3 plastic surgery procedures and came close to losing an eye.
Because she was taken to the ER, the bite was reported to the sheriff's department. It's required for medical people to report dog bites. The sheriff came to my home. Interestingly, they told me that neither my dog or I were in trouble. I had done my due diligence by having the dog on a leash. She was a working dog, we were on private property at a sheepdog trial. I did have to quarantine the dog for a period in case of rabies.
The bite victim did not sue me, but I lost my homeowner's insurance. It was extremely difficult to find another company that would sell me a policy and when I found one, the cost was exorbitant.
After much painful deliberation, I chose to have my dog euthanized. She was very young, but I do travel and there would be times that I would need to leave her in the care of someone else. She had many years ahead that would require extreme management and I felt that the chances for another incident were fairly high.
Incidentally, this dog had one litter of puppies before any of these situations occurred. I kept one and when he was 3 rehomed him as a pet, because he wasn't very keen on working. The couple loved him very much. When he was about 5 he bit a person who was dancing in the room. A couple of other incidents that were possible to dismiss as "border collie behavior" until, when he was 7, he ended up biting his owner in the face to the point where the person's nose was broken. He was euthanized after that.
Clearly there was a genetic component to this serious temperament issue that she passed on, though I also had her littermate. That dog was a saint her entire life.