Massachusetts Dog Bite Laws: Liability and Victim Rights

Massachusetts imposes strict liability on dog owners and keepers under Mass. Gen. Laws ch. 140, Section 155. A victim does not need to prove negligence or prior dangerous behavior. Liability is barred only if the victim was trespassing, committing a tort, or teasing or abusing the dog; children under seven are presumed innocent of provocation.

Estimate your claim: Use our free Massachusetts Dog Bite Settlement Calculator to see a rough settlement range based on the medical bills, the bite location, the victim's age, and Massachusetts's liability rule.

Overview of Massachusetts Dog Bite Laws

Massachusetts is one of the strongest strict liability states in the country when it comes to dog bite injuries. Under M.G.L. c. 140, § 155, a dog's owner or keeper is automatically liable for any damage the dog causes to a person's body or property. The victim does not need to prove the owner was negligent or that the dog had any history of aggression.

This statute covers all types of dog-related injuries, not just bites. If a dog knocks someone down, scratches them, or destroys their property, the same strict liability standard applies.

The law places the burden squarely on dog owners. If you own or keep a dog in Massachusetts, you are financially responsible for any harm that dog causes, with only narrow exceptions.

The Strict Liability Standard: M.G.L. c. 140, § 155

The core of Massachusetts dog bite law is M.G.L. c. 140, § 155. The statute states that if any dog does damage to the body or property of any person, the owner or keeper shall be liable for such damage.

If the owner or keeper is a minor, the minor's parent or guardian becomes liable instead.

What Victims Must Prove

To win a dog bite case in Massachusetts, the victim needs to establish only three things:

1. The defendant owned or kept the dog
2. The dog caused damage to the victim's body or property
3. The victim was not trespassing, committing another tort, or teasing, tormenting, or abusing the dog at the time

Notice what is absent from that list. The victim does not need to show:

• The owner knew the dog was dangerous
• The dog had bitten anyone before
• The owner failed to use reasonable care
• The dog had shown aggressive tendencies

This makes Massachusetts far more favorable to dog bite victims than states that follow the "one-bite rule," where owners escape liability if they had no prior knowledge of their dog's dangerous behavior.

Who Qualifies as a "Keeper"

The statute imposes liability on both owners and "keepers." M.G.L. c. 140, § 136A supplies the controlling definition, and it applies to "sections 137 to 174G, inclusive," a range that contains § 155. Under it, a keeper is "a person, business, corporation, entity or society, other than the owner, having possession of a dog."

Possession is the test. Someone who has the dog in their care can be a keeper even though they have never owned it.

This distinction matters in cases involving dog walkers, pet sitters, and other temporary caretakers.

Special Protections for Children Under 7

M.G.L. c. 140, § 155 includes a powerful provision protecting young children. If the victim is under seven years of age, the law presumes the child was not trespassing, committing a tort, or provoking the dog.

This shifts the burden of proof to the dog owner. The owner must affirmatively prove that the child was trespassing or provoking the dog in order to escape liability. In practice, this presumption makes it very difficult for dog owners to avoid responsibility when a young child is injured.

Legal Defenses for Dog Owners

The statute provides three specific defenses that can eliminate or reduce the owner's liability.

Trespassing or Committing a Tort

If the victim was trespassing on the owner's property or committing another tort at the time of the bite, the owner is not liable under § 155. However, the trespassing defense is harder to invoke against children under seven because of the presumption described above.

Teasing, Tormenting, or Abusing the Dog

If the victim provoked the dog by teasing, tormenting, or abusing it, the owner may escape liability. The provocation must be the direct cause of the bite. Minor interactions that would not cause a reasonable dog to bite typically do not qualify.

Comparative Negligence Is Not a Fourth Defense

Massachusetts does have a modified comparative negligence statute, M.G.L. c. 231, § 85, but it is written for negligence claims. By its own terms it governs actions "to recover damages for negligence," and it operates by comparing "the negligence of each plaintiff" to "the total negligence of all persons against whom recovery is sought."

A § 155 claim gives that comparison nothing to work with, because the owner's negligence is not an element of the claim in the first place. Section 155 supplies its own closed list of defenses: trespass, another tort, and teasing, tormenting, or abusing the dog. If a victim also pleads a separate ordinary negligence count against the owner, comparative negligence applies to that count in the usual way.

Damages Available to Dog Bite Victims

Dog bite victims in Massachusetts can pursue both economic and non-economic damages.

Economic Damages

• Medical bills, including emergency treatment, surgery, and rehabilitation
• Future medical costs for ongoing treatment or reconstructive procedures
• Lost wages from missed work during recovery
• Loss of earning capacity if injuries cause long-term disability
• Property damage

Non-Economic Damages

• Pain and suffering
• Emotional distress and psychological trauma, including PTSD
• Scarring and disfigurement
• Loss of enjoyment of life

Massachusetts does not impose a statutory cap on damages in dog bite cases. The full extent of the victim's losses can be recovered.

Triple Damages If the Dog Was Already Deemed Dangerous

If a hearing authority or a district court has already deemed the dog dangerous and that dog then wounds a person, M.G.L. c. 140, § 159 makes the owner or keeper "liable in tort to the person injured by the dog for 3 times the amount of damages sustained by such person." The same trebling applies when such a dog worries, wounds, or kills livestock or fowl.

That is why the dangerous dog process described below matters to an injured person and not only to the dog's owner. A prior dangerous dog finding is worth checking for with the local hearing authority before valuing a claim.

Statute of Limitations

Dog bite victims in Massachusetts must file their lawsuit within 3 years from the date of the injury. This deadline comes from M.G.L. c. 260, § 2A, which governs personal injury claims.

Key points about the filing deadline:

• The clock starts on the date of the bite or attack
• If the victim was a minor at the time of the injury, the 3-year period does not begin until the minor turns 18
• A claim against a city, town, or other public employer runs on a different track: M.G.L. c. 258, § 4 requires written presentment to that entity's executive officer within 2 years of the date the cause of action arose, and no civil action may be brought more than 3 years after it accrued
• Missing the deadline almost always results in permanent dismissal of the case

Dangerous Dog Designations: M.G.L. c. 140, § 157

Massachusetts has a detailed process for classifying dogs as "nuisance" or "dangerous" under M.G.L. c. 140, § 157. This process is separate from the civil liability statute but can result in serious consequences for dog owners.

How the Process Works

Any person may file a written complaint with the local hearing authority (typically an animal control officer or municipal official) alleging that a dog is a nuisance or dangerous. The hearing authority then investigates and holds a public hearing.

Based on credible evidence and testimony, the hearing authority can:

1. Dismiss the complaint
2. Deem the dog a nuisance dog
3. Deem the dog a dangerous dog

What Makes a Dog "Dangerous"

A dog may be deemed dangerous if it attacks a person or domestic animal causing physical injury or death without justification. However, the law includes important limitations. A dog cannot be deemed dangerous:

• Solely based on growling or barking
• Based on the dog's breed
• If the dog was protecting itself, its offspring, another animal, or a person from attack
• If the person threatened or attacked was committing a crime against the owner or keeper
• If the person was teasing, tormenting, or provoking the dog

Requirements for Owners of Dangerous Dogs

If a dog is deemed dangerous, the hearing authority may order the owner to:

• Confine the dog in a securely enclosed and locked pen with a secure roof, with sides embedded at least 2 feet into the ground if there is no secured floor
• Muzzle the dog securely and humanely when off the owner's premises, using a chain or tether with a minimum tensile strength of 300 pounds and no longer than 3 feet
• Maintain liability insurance
• Comply with any other conditions the hearing authority considers necessary

Statewide Ban on Breed-Specific Legislation

Massachusetts law explicitly prohibits cities and towns from regulating dogs in a manner that is specific to breed. No dog can be found to be a nuisance or dangerous based solely on its breed. This means breed-specific bans targeting pit bulls, Rottweilers, or any other breed are illegal throughout the state.

Criminal Penalties: M.G.L. c. 140, § 157A

Dog owners who fail to comply with a dangerous dog order face criminal penalties under M.G.L. c. 140, § 157A.

In the most serious cases, a court may order a dangerous dog to be euthanized under M.G.L. c. 140, § 157. If euthanasia is ordered and affirmed on appeal, the owner must reimburse the city or town for all reasonable costs incurred for housing and caring for the dog during impoundment and throughout the appeals process.

Landlord Liability for Dog Bites

Landlords in Massachusetts are generally not considered "owners" or "keepers" of a tenant's dog under § 155. Instead, landlord liability for tenant dog bites is governed by common-law negligence principles.

A landlord may be held liable if:

• The landlord knew or reasonably should have known the tenant's dog had dangerous propensities
• The landlord had the authority to require removal of the dog (through a lease provision, for example)
• The landlord failed to take reasonable steps to protect others

Simply owning the property where a tenant keeps a dog does not create strict liability for the landlord. The injured person must prove the landlord was negligent.

Dog Owner Responsibilities

Beyond the liability statute, Massachusetts imposes several obligations on dog owners:

• Licensing: A dog over the age of 6 months must be licensed with the licensing authority in the city or town where the dog is kept (M.G.L. c. 140, § 137). The length of the license period is set by that municipal licensing authority, not fixed at one year by statute (M.G.L. c. 140, § 136A)
• Rabies Vaccination: Dogs must be vaccinated against rabies before licensing
• Leash Laws: Many Massachusetts municipalities have local leash ordinances; check your city or town's bylaws
• Confinement: Dogs must be kept under the owner's control at all times
• Reporting Bites: Dog bites must be reported to the local board of health

How to File a Dog Bite Claim in Massachusetts

If a dog has injured you or your property in Massachusetts, take these steps to protect your legal rights:

1. Get medical treatment immediately. Your health comes first, and medical records create essential documentation for your claim.
2. Report the bite to local animal control and police. This creates an official record and may trigger a dangerous dog investigation.
3. Document the scene. Photograph your injuries, the location, and the dog if you can do so safely.
4. Collect the owner's information. Get their name, address, phone number, and homeowner's or renter's insurance details.
5. Identify witnesses. Get contact information from anyone who saw the incident.
6. Preserve physical evidence. Keep torn or bloody clothing and any other items damaged in the attack.
7. Contact a personal injury attorney. Because Massachusetts is a strict liability state, an experienced attorney can evaluate your case quickly.

Remember that you have 3 years from the date of the bite to file a lawsuit, but starting the process early preserves evidence and strengthens your claim.

More Massachusetts Laws

• Massachusetts Slip and Fall Laws
• Massachusetts Statute of Limitations