Mass. Gen. Laws » Part I Title XX Chapter 140
Massachusetts General Laws

Mass. Gen. Laws ch. 140, § 131M (2026)

Assault weapon or large capacity feeding device not lawfully possessed on August 1, 2024; sale, transfer or possession; punishment; exceptions

✓ current as of July 2026
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  Section 131M. (a) No person shall possess, own, offer for sale, sell or otherwise transfer in the commonwealth or import into the commonwealth an assault-style firearm, or a large capacity feeding device.

  (b) Subsection (a) shall not apply to an assault-style firearm lawfully possessed within the commonwealth on August 1, 2024, by an owner in possession of a license to carry issued under section 131 or by a holder of a license to sell under section 122; provided, that the assault-style firearm shall be registered in accordance with section 121B and serialized in accordance with section 121C.

  (c) Subsection (a) shall not apply to large capacity feeding devices lawfully possessed on September 13, 1994 only if such possession is: (i) on private property owned or legally controlled by the person in possession of the large capacity feeding device; (ii) on private property that is not open to the public with the express permission of the property owner or the property owner's authorized agent; (iii) while on the premises of a licensed firearms dealer or gunsmith for the purpose of lawful repair; (iv) at a licensed firing range or sports shooting competition venue; or (v) while traveling to and from these locations; provided, that the large capacity feeding device is stored unloaded and secured in a locked container in accordance with sections 131C and 131L. A person authorized under this subsection to possess a large capacity feeding device may only transfer the device to an heir or devisee, a person residing outside the commonwealth, or a licensed dealer.

  (d) Whoever violates this section shall be punished, for a first offense, by a fine of not less than $1,000 nor more than $10,000 or by imprisonment for not less than 1 year nor more than 10 years, or by both such fine and imprisonment, and for a second offense, by a fine of not less than $5,000 nor more than $15,000 or by imprisonment for not less than 5 years nor more than 15 years, or by both such fine and imprisonment.

[ Subsection (e) effective until August 5, 2025. For text effective August 5, 2025, see below.]

  (e) This section shall not apply to transfer or possession by: (i) a qualified law enforcement officer or a qualified retired law enforcement officer, as defined in the Law Enforcement Officers Safety Act of 2004, 18 U.S.C. sections 926B and 926C, respectively, as amended; (ii) a federal, state or local law enforcement agency; or (iii) a federally licensed manufacturer solely for sale or transfer in another state or for export.

[ Subsection (e) as amended by 2025, 14, Sec. 45 effective August 5, 2025. For text effective until August 5, 2025, see above.]

  (e) This section shall not apply to transfer or possession by: (i) a qualified law enforcement officer or a qualified retired law enforcement officer, as defined in the Law Enforcement Officers Safety Act of 2004, 18 U.S.C. sections 926B and 926C, respectively, as amended; (ii) a law enforcement officer as defined in section 1 of chapter 6E who is currently certified pursuant to section 4 of said chapter 6E; provided, however, that to qualify for the exemption under this subsection, the certification of a law enforcement officer as defined in section 1 of chapter 6E shall not be suspended, limited, or restricted and the officer shall be permitted to perform police duties and functions involving firearms in accordance with chapter 6E and the regulations promulgated thereunder; (iii) a federal, state or local law enforcement agency; or (iv) a federally licensed manufacturer solely for sale or transfer in another state or for export.

Notes of Decisions
Cited in 10 cases (6 in the last 5 years), 2014–2025 · leading case: Commonwealth v. Cassidy, 96 N.E.3d 691 (Mass. 2018).
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Commonwealth v. Cassidy, 96 N.E.3d 691 (Mass. 2018). · cites it 3× “A Superior Court jury convicted the defendant of unlawful possession of an assault weapon, G. L. c. 140, § 131M ; unlawful possession of four large capacity feeding devices, G.”
Worma v. Healey, 293 F. Supp. 3d 251 (D.D.C. 2018). · cites it 2× “Though the Act largely was styled after the federal assault weapons ban and initially echoed the federal ban's 2004 expiration date, the Massachusetts Legislature declined to let the Act expire and instead made it permanent in that year.”
Capen v. Campbell, 134 F.4th 660 (1st Cir. 2025). · cites it 2× “" Mass. Gen. Laws ch. 140, § 131M (the "Massachusetts Ban," or the "Ban").”
United States v. Trumbull, 114 F.4th 1114 (9th Cir. 2024). “10; Mass. Gen. Laws ch. 140, § 131M; N.J. Stat.”
Commonwealth v. Mokdad, 32 Mass. L. Rptr. 101 (Mass. Super. Ct. 2014). · cites it 6× “001 and 002) (G.L.c. 140, §131M). Mr. Mokdad moves for reconsideration of the court’s denial of his motion to dismiss (paper #10).”
Commonwealth v. Zachary Clough (Mass. Super. Ct. 2025). · cites it 3× ““[T}he ‘textual elements’ of the Second Amendment’s operative clause—‘the right of the people to keep and bear Arms, shall not be infringed’—’guarantee the individual right to possess -------------------------------------------- [3] Since October 2, 2024, a separate statute…”
Commonwealth v. Resende, 113 N.E.3d 347 (Mass. App. Ct. 2018). “e defendant subsequently was convicted of possession of a large capacity firearm, specifically, a nine millimeter pistol that could hold twelve rounds of ammunition, and possession of four large capacity feeding devices, specifically, one extended magazine for a nine millimeter…”
Commonwealth v. Guardado (Mass. 2023). “Accordingly, we conclude that the defendant's rights under the Second Amendment and his rights to due process were violated when he was convicted of unlawfully possessing ammunition although the jury were not instructed that licensure is an essential element of the crime.…”
Capen v. Campbell (D. Mass. 2023). “Mass. Gen. Laws ch. 140, § 131M. B. Procedural Background The complaint alleges that the Act violates plaintiffs’ Second Amendment rights to keep and bear arms by banning firearms and magazines “typically possessed by law-abiding citizens for lawful purposes.”
Commonwealth v. Dean F. Donnell, Jr. (Mass. 2025). “876 (2018) (rejecting Second Amendment challenge to, inter alia, assault weapon statute, G. L. c. 140, § 131M); Commonwealth v. Johnson, 461 Mass.”
— Mass. Gen. Laws ch. 140, § 131M(a) — 1 case
Commonwealth v. Zachary Clough (Mass. Super. Ct. 2025). ““[T}he ‘textual elements’ of the Second Amendment’s operative clause—‘the right of the people to keep and bear Arms, shall not be infringed’—’guarantee the individual right to possess -------------------------------------------- [3] Since October 2, 2024, a separate statute…”
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