Usually, a dog's owner is legally responsible for damage or injury the dog causes. But someone else may also be liable, if any of the following is true:
In states with the one-bite rule, someone who harbors or keeps a dog is just as liable as the legal owner of a dog if the dog causes injury. Many state dog-bite laws also make the "owner or keeper" of a dog liable for damage or injury the dog causes.
A "keeper" is someone with care, custody, and control of a dog. A Minnesota court put it this way:
“Harboring or keeping a dog means something more than a meal of mercy to a stray dog or the casual presence of a dog on someone's premises. Harboring means to afford lodging, to shelter or to give refuge to a dog. Keeping a dog…implies more than the mere harboring of the dog for a limited purpose or time. One becomes the keeper of a dog only when he either with or without the owner's permission undertakes to manage, control or care for it as dog owners in general are accustomed to do.” (Verrett v. Silver, 244 N.W.2d 147 (Minn. 1976).
Some courts, however, consider someone who has custody only for a very limited time to be a keeper. Here are some examples of how courts have ruled on the question of keeping or harboring a dog:
Some state dog-bite statutes limit liability to the owner of the dog. Under Washington law, for example, "mere keepers or possessors of a dog" aren't liable under the state statute, which limits liability to owners. (Guerrero v. Capron, 121 Wash. App. 1063 (2004).) But be careful not to take these statutes at face value. Sometimes another section of the statute, or a court interpreting it, defines "owner" as anyone who cares for or harbors the dog. For example, the Illinois statute says that if a dog injures a person, "the owner of such dog" is liable for the full amount of the injury. But another Illinois statute defines "owner" as anyone who keeps or harbors a dog. (510 Ill. Comp. Stat., § § 5/2.16, 5/16.)
Local ordinances may define "owner" more broadly than state laws. Under the Oklahoma statute, for example, "owner" is given a limited meaning. A Tulsa ordinance, however, defines owner as anyone "having the care or custody of or harboring, keeping or maintaining" a dog. Tulsa residents are subject to the broader local meaning, the Oklahoma Supreme Court has ruled. (Hampton ex rel. Hampton v. Hammons, 743 P.2d 1053 (Okla. 1987).)
A dog may have more than one owner, and so more than one person may be liable if the dog injures someone. For example, if you leave your dog with a friend for six months, and the dog bites someone, the friend may be liable as a "keeper." But you're still the owner, so you may be liable, too, either because of a dog-bite statute or, if you knew the dog was dangerous, the common law one-bite rule.
If the dog is owned or cared for by someone less than 18 years old, that minor's parents are probably legally liable in place of the minor. The dog-bite laws of some states say that explicitly. Some other states have laws that make parents responsible, to a limited extent, for damage their minor children cause. In other states, courts are likely to rule that the child's parents, who allow the dog on the premises and give it food and shelter, are liable because they are "keepers" of the dog.
In most circumstances, injured children can’t sue their parents for negligence. The reason is the "parental immunity" doctrine adopted by many states, which is based on the theory that family harmony would be disrupted if children could sue parents for failing to supervise and protect them adequately. But this immunity is not absolute. For example, a court allowed a lawsuit brought on behalf of a toddler after the family dog bit her severely. An Arizona court ruled that because the parents had a duty, as dog owners, to keep their dog from injuring anyone—including their own child—they were not immune from a lawsuit filed on behalf of their daughter. (Schleier ex rel. Alter v. Alter, 767 P.2d 1187 (Ariz. App. 1989).) The Arizona Supreme Court later abolished the parental immunity doctrine in that state. (Broadbent v. Broadbent, 184 Ariz. 74 (1995).)
It's a complicated area. Some states have allowed children to sue if the lawsuit isn't based on negligence, but instead on a dog-bite statute that imposes strict liability on dog owners. Others have not.
Anyone who lets a dog stay on his property may be liable for injury the dog causes if it's unreasonably careless to do so. For example, a New Jersey store was sued after a dog, tied outside the store by a shopper, bit a girl on her way inside. The court said that if a jury decided the store should have foreseen that the dog might bite someone, it would be liable for the injury. (Nakhla v. Singer-Shoprite, Inc., 500 A.2d 411 (N.J. Super. A.D. 1985).)
If you're hurt at work by a dog, your legal options may be limited. For example, a Massachusetts woman, bitten by her employer's dog, was not allowed to sue her employer; her only recourse was to file a worker's compensation claim. (Barrett v. Rodgers, 408 Mass. 614 (1990).)