MGL Chapter 140, Section 131K:
Approved Safety and Locking Devices

Massachusetts General Laws Chapter 140, Section 131K^[1] mandates that every firearm sold in the Commonwealth must include a safety device approved by the Colonel of State Police, designed to prevent discharge by unauthorized users. It treats the absence of an approved device as a product defect.

Approved Device Types

Approved devices include mechanical locks, solenoid use-limitation devices, key-activated or combination trigger or handle locks, radio frequency tags, automated fingerprint identification systems, and voice recognition, provided they are commercially available.

Legal Consequences

Sale without an approved device constitutes:

• Breach of warranty under Chapter 106, Section 2-314 (UCC implied warranty of merchantability)
• Unfair or deceptive trade practice under Chapter 93A, Section 2

Any entity responsible for manufacture, importation, or sale is jointly and severally liable for personal injury or property damage resulting from the failure to include or incorporate an approved device. Wrongful-death damages under Chapter 229 apply. Contributory and comparative negligence is not a defense when the claim is brought with the specified Chapter 93A or Chapter 106 claims. Disclaimers and waivers of Section 131K liability are void.

Liability Exceptions

The liability provisions do not apply to injuries that were:

• Self-inflicted (unless by a person under 18)
• Inflicted by the lawful owner or authorized user
• Inflicted in lawful self-defense
• Inflicted upon a co-conspirator during a crime

Exemptions

Section 131K does not apply to firearms distributed to law enforcement officers or members of the armed forces or organized militia who are authorized to acquire, possess, or carry them for official duties, when the firearms are distributed solely for use in connection with those duties. It also does not apply to firearms manufactured in or prior to 1899 or to replicas of those firearms that are not designed or redesigned for rimfire or conventional centerfire fixed ammunition. Section 131J separately excludes stun guns.

Chapter 135 Changes

Chapter 135 of the Acts of 2024^[2] made primarily terminological changes: "large capacity weapon" was changed to "large capacity firearm" throughout, and "weapon" was changed to "firearm." The substantive legal framework remains identical.

Related Provisions

Chapter 93A, Section 2 and Chapter 106, Section 2-314 provide the underlying consumer protection and warranty frameworks. Chapter 229 governs wrongful death claims. Section 131L establishes safe storage requirements. Section 131¾ governs the Secretary's rosters of assault-style firearms and approved firearms, which are separate from the Colonel's approval of safety devices under Section 131K.

Referendum Status

The terminological amendments are subject to the November 2026 referendum.