Does Massachusetts Follow the One Bite Rule? What Dog Bite Victims Need to Know

If a dog bites you in Massachusetts, you may wonder whether the owner can simply claim the animal had never bitten anyone before and walk away without liability. In many states, that argument holds legal weight under what is known as the one bite rule. Massachusetts, however, takes a fundamentally different approach.

Massachusetts is a strict liability state regarding dog bites and any other injury caused by a dog. That means the law does not give a dog a “free first bite,” and it does not require you to prove the owner knew the animal was dangerous. Understanding how this system works — and where its limits lie — can make a significant difference in how you handle a claim.

Key Insight: Massachusetts dog bite law covers more than bites. The same strict liability statute applies to any bodily injury or property damage a dog causes, including knocking someone down.

Does Massachusetts Follow the One Bite Rule?

Massachusetts does not use the one bite rule. Owners must consider their dogs a potential threat regardless of whether they have bitten anyone before. This is a meaningful departure from the common law standard that once governed these cases across the country.

The old common law theory for determining the liability of a dog owner was that the owner must have been shown to know or have reason to know of the dog’s propensity to bite — meaning the dog got one free bite, and after that, the owner could be held liable for subsequent attacks. Massachusetts changed this traditional method of determining liability for a dog bite by enacting a statute to cover these types of cases.

Many states operate under a “one bite” law, which allows dog owners to escape liability for a dog bite or attack if they can show their dog had no history of aggressive behavior — essentially, a first attack is forgiven. This is not the rule in Massachusetts. If you were injured by a dog in this state, you do not need to establish any prior history of aggression to pursue a claim. You can also read about how neighboring states handle this issue, including the one bite rule in New York and the one bite rule in New Jersey, for comparison.

How the One Bite Rule Works in Massachusetts

Because Massachusetts does not follow the one bite rule, the operative legal standard is strict liability. The specific statute is Massachusetts General Laws, Chapter 140, Section 155, which provides in part: “If any dog shall do any damage to either the body or property of any person, the owner or keeper … shall be liable for such damage.”

Strict liability means that the defendant — or dog owner in a dog bite case — is liable for an action regardless of what their intent or mental state was when the action occurred. In the case of personal injuries caused by a dog bite, there is no need for the victim to prove the dog owner was negligent.

State law makes owners “strictly liable” for most injuries and damage inflicted by their dogs, meaning it does not matter if the owner took precautions or if the dog had never misbehaved before. What sets Massachusetts apart is that this same strict liability law covers not only dog bites but also other injuries and property damage caused by dogs. To see how the one bite rule operates in states that still use it, the one bite rule in Tennessee and the one bite rule in Illinois offer useful contrasts.

Important Note: The strict liability standard under M.G.L. c.140, §155 applies to the dog’s owner or keeper — not automatically to every person connected to the incident, such as a landlord. Those situations are governed by a different legal standard covered later in this article.

What Victims Must Prove Under the One Bite Rule in Massachusetts

Because Massachusetts uses strict liability rather than the one bite rule, what you must prove as a victim is considerably simpler than in states that require evidence of prior dangerous behavior. The statute states that the owner or keeper of a dog is strictly liable when the dog bites or injures someone. “Strict liability” means the plaintiff does not have to prove that the defendant dog owner or keeper was negligent or knew that the dog was dangerous.

To qualify for strict liability under the statute, you generally need to establish three core elements:

• The defendant owned or kept the dog at the time of the incident.
• The dog caused bodily injury or property damage to you.
• You were not trespassing, committing another tort, or teasing, tormenting, or abusing the dog.

Under Massachusetts General Laws Chapter 140, Section 155, dog owners are held strictly liable for injuries caused by their dogs. This means you do not need to prove the owner was negligent or that the dog had a history of aggression — if a dog injures you, the owner is responsible.

Dog bite victims can seek economic damages for medical bills, plastic surgery, therapy, and lost wages. Non-economic damages cover pain and suffering, permanent scarring, counseling, loss of quality of life, and social anxiety. For a fuller picture of what happens after a dog bite in the state, see this overview of what happens if a dog bites someone in Massachusetts.

What Counts as Prior Knowledge in Massachusetts

Under the one bite rule framework used in other states, a victim must show the owner had prior knowledge of the dog’s dangerous tendencies — typically through a previous bite or documented aggressive behavior. In Massachusetts, prior knowledge is not a required element for strict liability under M.G.L. c.140, §155.

According to Massachusetts General Law Chapter 140, Section 155, an owner can be held civilly liable even if they were unaware that their dog might pose a danger or took precautions to prevent any harm. The absence of prior knowledge is simply not a defense under the strict liability statute.

That said, prior knowledge becomes relevant in two specific contexts. First, if you pursue a claim against someone other than the owner or keeper — such as a landlord — you will need to establish that person’s awareness of the dog’s dangerous behavior. The question becomes whether the property owner can be held liable by establishing that they “knew, or should have known, that the dog being kept on their property was dangerous, or had a propensity to be dangerous.”

Second, prior knowledge matters in negligence claims brought outside the statute. A dog bite victim in Massachusetts can recover compensation under the special statute and also under the doctrines of negligence, negligence per se, scienter, and intentional tort. In a scienter-based claim, prior dangerous behavior would be directly relevant to establishing liability. For comparison, states like Colorado and Washington have their own approaches to how prior knowledge factors into dog bite claims.

Exceptions and Defenses to the One Bite Rule in Massachusetts

Although Massachusetts law strongly favors injured victims, the strict liability statute does include defined exceptions. A dog owner or keeper is strictly liable for dog bites unless the victim was trespassing, teasing, tormenting, or abusing the dog, or was committing another tort. A child under the age of seven is presumed to have done none of those things, but the presumption is rebuttable.

The two primary defenses an owner can raise are:

1. Trespass: If you were unlawfully on the owner’s property at the time of the bite, the owner may not be liable under the statute. Lawful presence — such as being on a public sidewalk, in a park, or on the owner’s property with permission — means this defense does not apply.
2. Provocation: If you were teasing, tormenting, or abusing the dog immediately before the bite, the owner can argue provocation as a defense. The only defenses available to dog owners are that the victim was trespassing or that the victim provoked the dog. For children under age seven, the law presumes the child did not provoke the dog, placing an even greater burden on the owner.

Massachusetts does not recognize the defense of assumption of the risk in most dog bite contexts, which further limits what owners can argue to avoid liability. It is also worth noting that breed-specific legislation and bans are not allowed in Massachusetts, so a dog’s breed alone is not a factor in determining liability or as a defense.

Pro Tip: If you are a dog owner and your dog bites someone, document everything about the circumstances immediately — where the incident occurred, whether the injured person was on your property lawfully, and any behavior by the person toward the dog before the bite. These details directly affect which defenses may be available to you.

Dog Owner Liability Beyond the One Bite Rule in Massachusetts

Massachusetts law extends liability well beyond the dog’s registered owner. A dog owner can be held liable the first time their dog hurts someone and after any subsequent attacks. The law also applies to a dog’s “keeper,” which would be anyone responsible for the dog at the time, such as a dog walker or sitter.

Under Massachusetts’s strict liability rule, an owner is legally responsible for their dog’s behavior even when they are not in control of — or even in the same location as — their pet. This has practical implications for a range of scenarios:

• Pet sitters and dog walkers: If the dog was in the care of someone else, such as a dog walker, pet sitter, or groomer, that person may be liable for the dog’s behavior instead of or in addition to the owner.
• Minors as owners: When a minor owns the attacking dog, his or her parent or guardian is liable.
• Landlords: The Massachusetts dog bite rule does not mention landlords specifically, but legal cases have set precedents. Landlords are not held strictly liable like dog owners. Instead, for a landlord’s liability, the plaintiff usually needs to prove that the landlord had a duty to ensure safety and was negligent in that duty.

If a tenant repeatedly reports a dog’s aggressive behavior to the landlord and the landlord fails to take action, leading to an attack in the building, the landlord may be liable. Additionally, if the landlord is also the dog’s keeper — as in a scenario where the landlord watches the tenant’s dog — and the dog attacks someone while under their care, the landlord can be held liable as the keeper of the dog.

Typically, claims are covered by the dog owner’s homeowners’ or renters’ insurance policy and potentially by the dog owner’s assets or wages. You can also explore how liability extends to keepers and third parties in other states, such as the one bite rule in Michigan and the one bite rule in Florida.

What to Do After a Dog Bite in Massachusetts

The steps you take immediately after a dog bite affect both your health and the strength of any legal claim you pursue. Acting quickly and methodically gives you the best chance of a full recovery — physically and legally.

Seek immediate medical attention. Dog bites carry a high risk of infection and can cause deep tissue damage, nerve damage, and scarring. Even if the wound seems minor, professional medical treatment creates a record of the injury that will be necessary for your claim.

After addressing your immediate medical needs, take the following steps:

1. Identify the dog and owner. Obtain the name, address, and contact information of the dog owner. If the owner is not present, try to obtain a description of the dog and note where it went.
2. Report the incident to animal control. Filing a report creates an official record and triggers the state’s process for evaluating whether the dog poses an ongoing public safety risk. Massachusetts has two classifications of dogs that have bitten someone — nuisance dogs and dangerous dogs. These can also be imposed in response to complaints filed by citizens, and a public hearing will be held to determine if a dog deserves either classification.
3. Document everything. Photograph your injuries, the location of the attack, and any visible evidence such as a broken leash or lack of fencing. Document all interactions and communications with the dog’s owner and any insurance companies involved. These records support your claim by providing clear, chronological evidence of the incident and its aftermath.
4. Preserve witness information. Collect names and contact details for anyone who saw the attack. Expert testimonials from medical professionals or animal behaviorists might also play a role in establishing the extent of injuries or the dog’s behavior pattern.
5. Be aware of the filing deadline. The Massachusetts statute of limitations for personal injury claims is three years. That means you have three years to file a negligence or strict liability lawsuit if someone’s dog has injured you or damaged your property.

Important Note: Massachusetts law under M.G.L. c.112, §12Z also requires certain healthcare providers to report dog bites to public health authorities. If you seek medical care, this reporting may happen automatically, but filing your own report with local animal control ensures the incident is on record regardless.

These claims are not always simple. Coverage issues, questions about who qualifies as an owner or keeper, defenses involving trespass or alleged provocation, and disputes involving landlords or property owners can all materially affect the outcome of a case. Consulting with a personal injury attorney who handles dog bite cases in Massachusetts is the most reliable way to understand your options after an attack.

If you are researching how other states compare, the one bite rule in North Carolina, the one bite rule in Minnesota, and the one bite rule in Wisconsin each take a different approach to owner liability that is worth understanding alongside Massachusetts’s strict liability framework.