California has a dog-bite statute listed under its Civil Code section 3342 which states in part: "(a) The owner of any dog is liable for the damages suffered by any person who is bitten by the dog while in a public place or lawfully in a private place, including the property of the owner of the dog, regardless of the former viciousness of the dog or the owner's knowledge of such viciousness." This means that under California law, even if a dog is good natured throughout its life but then one day out of the blue decides to bite somebody in a single instance or consume a small child, the owner could still be liable. Other states without such "strict liability" statutes will oftentimes have laws that will hold owners responsible for bites only if their dog was previously known to have bitten before or have an otherwise hostile disposition. These are often referred to as "one-bite" states, because after a dog bites once, the dog will often thenceforth be deemed to be knowingly hostile.
CA Dog Bite Law "Negligence"
Dog owners can also be held liable for their dog biting people under a general theory of negligence, even if a state has no specific dog bite statutes of any kind.
Under negligence, a dog owner must take reasonably prudent steps to prevent reasonably foreseeable attacks by their pet in order to avoid liability. (This differs from "strict liability" statues which can hold the owner liable even if they prove that they took reasonable precautions to prevent their dog from biting someone.)
Just what these prudent steps should be will always be different with each circumstance. The preventive safety measures with a large aggressive Pit Bull will likely be different than those concerning a small mild-mannered Chihuahua. Oftentimes, safety measures will concern the question of the dog being properly leashed. Is the dog confined to an area where children won't be able to accidentally wander into? Has the owner done everything reasonable to see that the dog is under control around others?
There are general exceptions to the rule of dog owner liability, even in states with strict liability dog-bite statutes.
1. The police, military or government agencies that use dogs in the course of their work or investigations that end up biting people. Translation: If you rape and pillage a community while smuggling a ton of heroin and then get bit by the German Sheppard the cops use to chase you down, don't think that you can get rich by suing the police. (Though admittedly this immunity often only applies towards bites against criminal or hostile suspects. Innocent bystanders may still have a valid claim, depending on the law of a given state.)
Exception Number Two
2. Trespassers. If someone wanders on to your property without your permission, many states will not hold you liable if your dog ends up biting them. In fact, many people keep dogs specifically in the hopes that they will keep out trespassers. California's dog-bite statute specifically allows for this exception.
Please note however that whether or not someone is a "trespasser" is itself a separate legal question. For instance, the law allows for postal employees to travel on to your property without your permission in order to deliver your mail. The "trespass" exception would not protect you from liability if your dog bites the mailman in this instance.
Exception Number Three
3. Assumption of the risk. If someone knows that a certain action could likely result in a dog biting them and proceeds to take that action anyway, that person is said to have "assumed the risk" and will not be able to hold the owner liable. (Example: If a dog owner tells you, "Don't go into my back yard and play with my dog. He is in a bad mood today and has been trying to bite anything that moves!" Then afterwards, you completely ignore the warning by going into the owner's back yard and playing with the dog. You will unlikely be able to hold the owner liable if you get bit since you assumed the risk in this instance.
Sometimes, the assumption of the risk is implied. For instance, courts have found that strict liability statues do not apply to dogs that bite veterinarians during the course of treating the pet. Such risks are apparently in the nature of the business for them.
Exception Number Four
4. Negligence. Some states may shield the owner from liability when a person negligently contributes to the dog bite. In practical terms, this defense operates similarly to "assumption of the risk". The only difference is that one doesn't ask "What did the bite victim know before approaching the dog?" Instead, one asks, "What should the victim have known, assuming that he or she is a reasonable person?"
A straightforward example would be someone approaching a dog after ignoring a clearly posted "Beware of Dog" sign. Courts may find that there was either an assumption of the risk or contributory negligence in this instance.
Exception Number Five
5. Provocation. In instances where someone mistreats or provokes a dog into biting him, courts will usually not hold the owner liable. For instance, unjustifiably beating a dog will often provoke it to bite back in retaliation.
Just what constitutes legal "provocation" is often a question of fact for the courts to decide in each instance. Generally, mere attempts to pet, feed or otherwise peacefully interact a dog will not be considered sufficient provocation. There usually must be some action that courts would recognize as mistreatment.