Depending on the state you live in, proving knowledge of a dog’s dangerous history may or may not be required by courts to hold the owner liable for a dog bite injury.
In California, for example, the law applies strict liability to dog owners in cases of dog bite injury. This means the victim does not need to prove that the owner has been negligent or careless to win a dog bite case. In addition, the owner may still be liable even if the dog has not shown any vicious or dangerous propensity, or even if the owner has no prior knowledge of such propensity prior to the time of the incident.
On the other hand, in states that do not apply strict liability rules on dog bite cases, owners may not be held legally responsible for injuries caused by their dogs unless the victim proves that they had knowledge of the dog’s dangerous propensity prior to the incident. In the state of Georgia, for example, the owner can use lack of such knowledge as a legal defense against the victim’s dog bite claim. Also, proving that the owner had such knowledge is usually difficult and does not guarantee victory.
For a more detailed answer, you may see a local attorney who handles dog bite cases with whom you can discuss the rules on liability that applies in your area.