An appeals court in Maryland set a precidence when it declared that a dog owner can be declared negligent simply for owning a pitbul, or any breed mixed with a pitbul and it attacks someone. This precident changed from when it was declared previously that the victim (plantif) had to prove that the owner (defendant) knew that their dog had violent tendancies. This means in Maryland your homeowners or liability insurance could refuse to cover you, or could jack their rates extremely high, even though pitbuls are not in any more danger of attacking anyone than any other breed, but because they are declared inherently dangerous.
I live in Virginia and we have a pitbull, and it was very difficult to find a rental place that did not have a breed restriction, simply because plantifs can go after owners of properties in this state, addition to tennants, and there is not liability cap. There are pitbull fighters everywhere in this country and around the world, but 99% of these dogs are not used for fighting. They are sweet and gentle when raised to be sweet and gentle. If you ban or make it impossible to own a breed of dog stereotypically associated with fighting, the fighters will just start fighting another breed, perhapse a similar one, like boxers, or another simmilar terrier.
I have a sweet pitbull who only weighs 50 pounds and wouldn't even bite Michael Vick.