Massachusetts does not use one simple statewide blade-length rule for every knife. Instead, General Laws c. 269, § 10(b) regulates a detailed list of weapons and knife types when carried on the person or under a person’s control in a vehicle. A major 2024 court decision also invalidated the statute’s switchblade-carry prohibition. [1] [2]
The often-repeated 1.5-inch figure is not a universal Massachusetts blade limit. It appears in the statute’s wording for one category of automatic spring-release knife, and the Supreme Judicial Court held that switchblade restriction unconstitutional in Commonwealth v. Canjura.
What knives may you own in Massachusetts?
Massachusetts law does not impose a general ban on owning every folding knife or fixed blade. The most important statewide statute focuses on carrying listed weapons, not ordinary household possession.
However, a knife can still become evidence of another offense based on how it is used, displayed, stored, sold, or carried. Schools, courts, government buildings, employers, and private properties may also impose separate restrictions.
Which knives are listed in the statewide carry law?
General Laws c. 269, § 10(b) lists weapons including a stiletto, dagger, ballistic knife, dirk knife, double-edged knife, and several other specifically described instruments. It prohibits carrying a listed weapon on the person or under one’s control in a vehicle unless an exception or other legal authority applies. [1]
Some statutory terms are technical and have been interpreted in court decisions. A product name used by a seller does not necessarily determine the legal classification. Blade shape, sharpened edges, opening mechanism, construction, and the circumstances of carry may matter.
Are switchblades and automatic knives prohibited?
In August 2024, the Massachusetts Supreme Judicial Court held that switchblades are protected “arms” under the Second Amendment and that the switchblade-carry prohibition in § 10(b) violated the Second Amendment. The court therefore reversed the defendant’s switchblade conviction. [2]
The statutory page may still display switchblade wording even though Canjura made that portion unenforceable. The decision did not erase every other knife category in § 10(b), nor did it authorize threatening use or possession in every location. Massachusetts revised its model jury instruction in 2026 to reflect that the switchblade portion may no longer support conviction. [3]
Is there a statewide blade-length limit?
No single blade-length threshold governs all ordinary knives statewide. The statute’s 1.5-inch wording was tied to the automatic spring-release category addressed by Canjura; it should not be presented as a blanket limit for every pocket knife.
A city or town may have additional rules, and particular knife designs may fall within another listed category regardless of length. Verify both the current state law and the local code where you plan to carry.
May you carry a common pocket knife?
A conventional single-edged manual pocket knife is not automatically prohibited merely because it is a knife. The legal analysis depends on whether its design fits a listed category, where and how it is carried, and how it is used or displayed.
Open carry is not a universal safe harbor. Section 10(b) addresses carrying listed weapons and control inside a vehicle rather than creating a simple open-versus-concealed rule. Avoid displaying any knife in an angry or threatening manner.
What rules apply at schools and colleges?
General Laws c. 269, § 10(j), effective August 5, 2025, prohibits carrying a firearm or other dangerous weapon in school buildings or grounds, at school-sponsored events, on certain student transportation, and at colleges and universities without the required written authorization, subject to the statute’s details and exceptions. [1]
Practical rule: do not bring a knife to a school, college, school bus, or school activity unless you have clear written authorization for a lawful purpose and have confirmed every applicable policy.
Can cities adopt stricter knife rules?
Massachusetts’ official legal guide tells readers to check city and town ordinances and specifically points to local weapon rules, including Boston’s ordinance. [4]
Because local requirements can differ, a knife that is not prohibited by the statewide summary may still be restricted by a municipal ordinance or venue rule. Check the official code for the municipality where you live, work, or travel.
What travel and private-property rules matter?
A vehicle does not remove § 10(b) concerns because the statute expressly addresses weapons under a person’s control in a vehicle. Keep any lawful knife closed or sheathed and secured, and do not leave it accessible to an unauthorized person.
Employers, venues, landlords, and property owners may prohibit knives. The Transportation Security Administration prohibits knives in carry-on baggage except for plastic or round-bladed butter knives; checked-baggage and airline requirements still apply. [5]
What should you verify before carrying?
- Whether the design could be classified as a dagger, dirk, double-edged knife, stiletto, or another listed weapon.
- Whether Canjura affects the specific automatic-knife issue involved.
- Whether a school, court, government building, employer, venue, or property owner prohibits the knife.
- Whether the city or town has a stricter ordinance.
- The laws of every other jurisdiction on the travel route.
Conclusion
Massachusetts knife law is category-based rather than governed by one universal blade limit. The 2024 Canjura decision invalidated the switchblade-carry prohibition, but other listed knife restrictions, school rules, local ordinances, and conduct-based offenses remain important.
Last reviewed: August 24, 2026.
This article provides general information, not legal advice. Knife laws and their interpretation can change and may depend on design, carry method, purpose, location, local ordinance, and conduct. Verify current law through official sources or consult a qualified Massachusetts attorney about a specific situation.
Sources & References
- [1] Massachusetts General Laws c. 269, § 10. State carry restrictions, listed weapons, vehicle control, school rules, and statutory exceptions.
- [2] Commonwealth v. Canjura, 494 Mass. 508 (2024). Supreme Judicial Court decision holding the switchblade-carry prohibition unconstitutional.
- [3] Massachusetts Model Jury Instruction 7.680. Revised February 2026 instruction addressing carrying certain dangerous weapons and the effect of Canjura.
- [4] Massachusetts law about weapons, non-firearms. Official state legal guide linking statutes, cases, and local ordinances.
- [5] Transportation Security Administration — Knives. Federal carry-on and checked-baggage guidance.
