Description of the rule
The one bite rule says that an owner, harborer or keeper of any domestic animal (a dog, cat or any other domestic animal) shall be held legally liable for damages caused by the animal if it is shown that (a) the animal had a propensity to do something harmful which was unusual for the animal's class (such as biting people, scratching them or knocking them down), (b) the owner, harborer or keeper of the animal was aware of this propensity or dangerous propensity prior to the incident in question, and (c) the animal's propensity to act harmfully caused damages to a person or property in the incident in question.
The Restatement (Second) of Torts, section 509, sets forth the one bite rule as follows:
§ 509. Harm Done by Abnormally Dangerous Domestic Animals.
Except as stated in § 517, a possessor of a domestic animal which he has reason to know has dangerous propensities abnormal to its class, is subject to liability for harm caused thereby to others, except trespassers on his land, although he has exercised the utmost care to prevent it from doing the harm.
The Restatement, quoted above, uses the phrase "has reason to know." The significance of it is explained in Restatement (Second) of Torts § 12 (1965):
§ 12. Reason to Know; Should Know
(1) The words "reason to know" are used throughout the Restatement of this Subject to denote the fact that the actor has information from which a person of reasonable intelligence or of the superior intelligence of the actor would infer that the fact in question exists, or that such person would govern his conduct upon the assumption that such fact exists.
(2) The words "should know" are used throughout the Restatement of this Subject to denote the fact that a person of reasonable prudence and intelligence or of the superior intelligence of the actor would ascertain the fact in question in the performance of his duty to another, or would govern his conduct upon the assumption that such fact exists.
How the rule relates to dog bite law in general
The one bite rule is one of several methods of establishing the liability of a defendant in a dog bite case. Other methods include negligence and negligence per se, as set forth in Legal Rights of Dog Bite Victims in the USA. In certain situations, victims have even based their claims on less ordinary causes of action such as nuisance, battery, assault and intentional torts.
The one bite rule is relevant the first time that a canine attacks a human being. In such a case, the paramount legal issue is the extent to which the state having jurisdiction adheres to the English common law pertaining to injuries inflicted by domestic animals. The common law shielded the owner of a domestic animal from civil liability to the first victim of each of his animals. This absolving principle came to be known variously as the "one bite rule," the "first bite rule," or the "first bite free" rule.
The one-bite rule underlies civil and criminal actions in modern America, and is applicable in every state and the District of Columbia. A minority of American states (listed in Legal Rights of Dog Bite Victims in the USA) use the one-bite rule to determine legal liability. The majority of states and the District of Columbia have passed "dog bite statutes" that modify the one-bite rule in specific circumstances. (The list of those states also is in Legal Rights of Dog Bite Victims in the USA.) Criminal laws which apply to the owners, keepers and harborers of dogs are generally based upon the one-bite principle, in that criminal liability usually does not result from dog attacks unless the dog previously engaged in similar behavior.
It should be noted that the one-bite rule applies to cases involving any domestic animal, and any type of injury (such as a knock-down or trip-and-fall). For example, an owner's liability for injuries by his cat would be determined by the one-bite rule. In the absence of a strict liability statute or ordinance in the jurisdiction where the incident happened, the factual issue would be whether the cat was known to its owner, harborer or keeper to inflict injuries on people or property a certain way. If so, and if the cat were to do it again in that way, then that person would be liable under the one-bite rule.
Rationalle for the rule
The rationale of the one bite rule was that domestic animals by definition were not injurious, and therefore liability could be predicated only on the defendant's knowledge that a particular animal had a propensity to behave in manner that was injurious to humans. Again, the rule applied to any type of injury, whether or not a bite.
The rule provided not only a shield for the animal's owner but also a sword for its victim, because it justified compensating any victim -- after the first one -- who was injured by the same dangerous propensity provided that the owner, keeper or harborer of the dog knew or should have known about it. The cause of action was founded on the defendant's scienter (i.e., knowledge) of his dog's dangerousness. For that reason, this cause of action has been referred to as the "scienter cause of action," or as "common law strict liability." Because the gist of the tort "is the keeping of a thing known to be dangerous, one who keeps or harbors an animal owned by another may be liable, if he has such knowledge." Prosser or Torts, chapter 10, section 57, page 441.
The Restatement (Third) of Torts, section 23, comment (b), sets forth the rationale of holding dog owners strictly liable for keeping vicious dogs:
Ownership of animals such as dogs and cats is widespread throughout the public; therefore, the limited risks entailed by ordinary dogs and cats are to a considerable extent reciprocal. Accordingly, the case on behalf of strict liability for physical harms that all such ordinary animals might cause is weak. However, even though animals in such categories generally entail only a modest level of danger, particular animals may present significant and abnormal dangers.... Even if ... retention [of such an animal] is itself proper, an abnormally dangerous animal is by definition unusual; owning such an animal is an activity engaged in by a few that imposes significant risks on others within the community. In these circumstances, strict liability is fairly imposed.
An actual bite is not required
It has been repeatedly stated in the court decisions that the name "one-bite rule" is a misnomer, and that the rule applies to any injury whether or not it was caused by a bite, and that in a dog bite case the proof of the dangerous propensity does not require showing a prior bite to a person but simply conduct that should have put the owner, keeper or harborer on notice that the dog wanted to bite a person.
“[T]here can be circumstances, short of an actual bite, which suffice to give the dog owner reason to know of the dog’s dangerous tendency; for example, the dog, without provocation, may lurch at a person evidently attempting to bite, but fails in this endeavor when the person successfully withdraws” (Restatement (Third) of Torts: Phys. & Emot. Harm, section 23, comment (c), “Scienter.”).
“A dog is not necessarily regarded as entitled to one bite. It is enough that the possessor of the animal knows that it has on other occasions exhibited such a tendency to attack human beings . . . as should apprise him of its dangerous character. Thus, the fact that a dog has to his knowledge unsuccessfully attempted to attack human beings . . . is sufficient to [show scienter].” (Restatement (Second) of Torts, section 509, comment (g).)
When it comes to dogs, therefore, the test in a dog bite case is whether the dog previously showed a desire to bite a person (i.e., a vicious temperament). (See, i.e., Steagald et al. v. Eason et al. (2017) __ GA __ : "An attempt to bite in
the absence of provocation most certainly may be proof of a propensity to bite without provocation.") In a "knock-down" case, the test would be whether the dog played too hard (dangerous behavior).
Importance of the rule in states having a dog bite statute
The one bite rule is important even in states that have a dog bite statute, because the wording of the statute might not apply to any particular dog bite incident.
The dog bite statutes are worded differently throughout the country. They might or might not apply to keepers and harborers as well as owners, and to injuries by means other than biting. They might provide for full compensation, or payment of just medical bills, or payment of medical bills and other economic losses (like loss of income), or double compensation under some circumstances. Some do not apply during the day, or if the dog owner posted a "bad dog sign," or if the victim had provoked the dog weeks before. Even though they are worded as strict liability laws, moreover, the court decisions permit a variety of defenses that vary from state to state.
For that reason, it is important to keep in mind that even if the dog bite statute does not apply to a particular defendant, or does not provide sufficient compensation, the victim can still assert the scienter cause of action, because it is always available in every state, and in almost every state can also assert causes of action such as negligence and negligence per se.
The scienter cause of action can be directed against not only the dog's owner, but also its harborer or keeper:
A person, although not the owner of a vicious dog, may make himself liable to others by knowingly keeping or harboring the dog upon his premises, after knowledge of his vicious propensities, and this is true even when such keeping is without the consent and against the wishes of the animal's owner. ... The owner of an animal is the person to whom it belongs. Whether or not a person is a keeper depends upon the peculiar facts and circumstances of each individual case. A man may own an animal and yet not be its keeper. The word 'keeper' is equivalent to 'the person who harbors.' Harboring means protecting. So one who treats a dog as living at his house, and undertakes to control his actions is the owner or keeper within the meaning of the law; but the casual presence of an animal on his premises, if not so treated, does not constitute him such owner or keeper. (3 C.J.S. 1266, § 165.)
Limitations on defenses
Contributory negligence and comparative negligence are not defenses against the scienter cause of action. This is expressed in Restatement of Torts, section 515, subsection (1): "A plaintiff is not barred from recovery by his failure to exercise reasonable care to observe the propinquity of a wild animal or an abnormally dangerous domestic animal or to avoid harm to his person, land or chattels threatened by it." Comments (a) and (b) to section 515 provide the reasoning for this rule:
The possessor or harborer of the animal takes the risk of answering for any harm done by it while out of his control not only to the careful and competent but also to those whose care and competence is below the standard to be expected of the reasonable man. Therefore, a person harmed by such an animal which with or without fault of the owner gets out of his control is not barred from recovery because had he exercised ordinary vigilance, skill and competence he could have escaped injury.
Since the strict liability of the possessor of an animal is not founded on his negligence, the ordinary contributory negligence of the plaintiff is not a defense to such an action. The reason is the policy of the law which places the full responsibility for preventing the harm upon the defendant. Thus where the plaintiff merely fails to exercise reasonable care to discover the presence of the animal, or to take precautions against the harm which may result from it, his recovery on the basis of strict liability is not barred.
Trespass is not a defense against the scienter cause of action in all states. Trespass was not a defense at the common law. (Dog Owners' Liability: Statutory Effects, Duke Law Journal, Vol. 1960, No. 1 (Winter, 1960), pp. 146-149.) The case of Radoff v. Hunter (1958) 158 Cal.App.2d 770, for example, held that keeping a guard dog on one's premises, without making the dog's presence obvious or warning of its presence, shall result in liability toward all persons that the dog injures, whether such person are considered invitees, licensees or trespassers. In the Radoff case, the plaintiff was a trespasser who was bitten by the defendants' watch dog, which was kept on a chain in a parking lot behind the defendants' store. The dog often could not be seen and no sign warned of its presence. Ruling that trespass was not a defense to the scienter cause of action, the court stated that "the keeping of the trained watchdog, under conditions where at times he was concealed from view and where no warning was given of his presence, was similar to maintaining a trap whereby invitees, licensees or trespassers might be injured."