🦌 Montana Knife Laws
Overview
Montana has statewide preemption — local governments cannot create additional knife restrictions beyond state law. Both open and concealed carry of knives are legal. There is no general blade length restriction. All common knife types are legal to own and carry.
Quick Legal Facts
Carry Laws & Blade Length
Open carry of all knives is legal in Montana. No statute restricts the open carry of any knife type or blade length. The 2017 amendment (HB 251) removed all knife references from the concealed weapons statute (45-8-316), and no separate open carry restriction has ever applied to knives.
Concealed carry of all knives is legal without a permit. In 2017, HB 251 amended 45-8-315 and 45-8-316 to remove all knives (dirks, daggers, swords, and knives with blades 4 inches or longer) from the concealed weapons definition and prohibition. The definition of 'concealed weapon' in 45-8-315 now applies only to firearms. Montana is a constitutional carry state for firearms under 45-8-316(3), but knives are entirely unrestricted for concealed carry.
No general blade length limit for carry or possession. The only blade length threshold in Montana law is the 4-inch limit for knives in school buildings under 45-8-361. Outside of school property, there is no maximum blade length for any type of carry.
Statute: 45-8-361.
Knife Type Legality
| Knife Type | Status | Details |
|---|---|---|
| Switchblades | Legal | Switchblades are legal to own, carry, buy, sell, and manufacture. Montana's former switchblade ban (45-8-331) was repealed in 2019 by HB 155 (Chapter 119, Laws of 2019). The old law had prohibited carrying, possessing, or selling switchblades with blades 1.5 inches or longer. Since repeal, no Montana statute restricts automatic knives. |
| Balisongs / Butterfly Knives | Legal | Balisong (butterfly) knives are legal. No Montana statute specifically mentions, defines, or restricts balisong knives. Montana does not regulate knives by type or opening mechanism. The statewide knife preemption statute (45-8-352) prevents local governments from enacting bans on any knife type not prohibited by state law. Statute: 45-8-352. |
| Disguised Knives | Legal | Disguised knives (belt buckle knives, lipstick knives, cane swords, pen knives, etc.) are not prohibited by any Montana statute. Montana does not ban knives based on concealment mechanism or disguise. The 2017 amendment specifically removed 'sword cane' from the concealed weapons prohibition in 45-8-316. Preemption under 45-8-352 prevents local bans. |
| Assisted-Opening | Legal | Assisted-opening knives are legal. No Montana statute specifically addresses or restricts assisted-opening knives. Montana does not regulate knives by opening mechanism. Even fully automatic switchblades are legal following the 2019 repeal of 45-8-331, so assisted-opening knives are clearly legal without question. |
| Ballistic Knives | Legal | No Montana statute specifically mentions, defines, or prohibits ballistic knives. They are not listed in any state weapons prohibition. Legal under state law. However, federal law (15 U.S.C. 1245) separately prohibits the possession, manufacture, sale, and import of ballistic knives in interstate commerce and federal jurisdictions regardless of state law. Statute: 45-8-352. |
Legal Disclaimer
This information is provided for general educational purposes and should not be construed as legal advice. Laws change frequently and local ordinances may impose additional restrictions beyond state law. Always verify with official state sources before making decisions about knife carry or ownership. KnifeInformer is not a law firm — consult a qualified attorney for specific legal questions.
