Source: Criminal Model Jury Instructions for Use in the District Court
Revised: February 2026
Statute: G.L. c. 269, § 10(b) (first clause)
The Commonwealth must prove three things beyond a reasonable doubt:
The statute lists these per se prohibited weapons:
- Stiletto
- Dagger
- Device or case enabling a knife with a locking blade to be drawn at a locked position
- Ballistic knife / knife with detachable blade capable of being propelled by any mechanism
- Dirk knife
- Knife with a double-edged blade
- Knife with automatic spring release device (blade over 1.5 inches) [see Canjura note below]
- Slung shot
- Blowgun
- Blackjack
- Metallic knuckles or knuckles of any substance with same or similar effect
- Nunchaku, zoobow (kung fu sticks), or similar two-stick weapon connected by rope/chain/wire/leather
- Shuriken or similar pointed starlike object intended to injure when thrown
- Armband with metallic spikes, points, or studs
- Cestus or similar material weighted with metal and worn on the hand
- Manrikigusari or similar length of chain having weighted ends
Trial judge should consider whether further definition of the specific weapon is necessary. Miller, 22 Mass. App. Ct. 694, 696 (1986); Higgins, 85 Mass. App. Ct. 534, 536-538 (2014). Where weapon is admitted as exhibit, jury may conclude from their own observations. Fancy, 349 Mass. 196, 204 (1965); Stallions, 9 Mass. App. Ct. 23, 25-26 (1980).
Defendant must have had more than momentary possession and moved the weapon from one place to another. Seay, 376 Mass. 735, 737 (1978).
Defendant must have known they were carrying/controlling the weapon. Jury may examine actions, words, surrounding circumstances, and reasonable inferences.
In Commonwealth v. Canjura, 494 Mass. 508, 511 (2024), the SJC held that the portion of § 10(b) prohibiting carrying a switchblade knife is unconstitutional under the Second Amendment.
Key holdings:
- "Second Amendment protections subsume more than just firearms." Canjura, 494 Mass. at 511, quoting Heller, 554 U.S. 570, 582 (2008). See also Caetano v. Massachusetts, 577 U.S. 411, 411-412 (2016) (per curiam) (stun guns are "arms").
- Applied the Bruen two-part framework: (1) switchblade is an "arm" under the plain text of the Second Amendment; (2) Commonwealth did not meet its burden of identifying analogous historical regulations of switchblades at the time of the founding or ratification of the Fourteenth Amendment. Id. at 511-518.
- Switchblade knives are in "common use" today and are not "dangerous and unusual." Id. at 515-516 & n.10. (Court noted SCOTUS has not clarified how "common use" fits within Bruen's framework.)
- Court declined to opine on the constitutionality of the prohibitions on any of the other weapons in § 10(b). Id. at 518 n.14.
Advance notice of defense (Note 1): Defendant may not rely on a defense based on license, exemption, or claim of authority unless advance notice filed with court and prosecutor. Mass. R. Crim. P. 14(b)(3).
Nature of the weapon (Note 3): Purpose of § 10(b) is "to outlaw the carrying of those knives which are primarily designed for stabbing human beings or for other unlawful objectives." Court must determine on motion for required finding whether weapon qualifies. Miller, 22 Mass. App. Ct. 694, 696 (1986); Higgins, 85 Mass. App. Ct. 534, 536-538 (2014).
Relationship to 7.700: This instruction covers the first clause of § 10(b) (carrying listed weapons). Instruction 7.700 covers the second clause (dangerous weapon when arrested). The second clause is inapplicable to firearms (covered by § 10a) and to per se dangerous weapons listed in the first clause.