If you reside in the state of Montana, the Constitution of said state allows knives and weapons as follows:

Everyone has the right to keep and bear arms in defense of their home, property or family. They also have this right, during civil power, when if they are legally called. This shall not be in question. However, nothing contained herein will allow for concealed weapons to be carried at any time. Weapons must not be concealed ever.

MT CONST Art. 2, § 12


No switchblades or automatic opening knives are allowed per Montana state Law. Exceptions for collectors or switchblade knives that have less than one and a half inch blade. Only if collectibles are registered within the sheriff’s district of the county may these be kept on premises. There are tight stringent rules regarding this so it’s vital to comply and follow them to the letter for everyone’s safety.

Switchblade Knives:

1. Persons who carry or bear said weapons within a motor vehicle or other conveyance, who own or operate stores or who sell or give away such knives are subject to punishment by the law of a fine that shall not exceed $500 or the possibility of imprisonment in county jail for no more than six months or both. Terms can be run together.

2. Bona fide collectors with a registered collection at the Sheriff or in the county therein, are exempted from this section of law. Registration must be on the record.

3. Switchblades are defined as any knife with a blade of 1 and 1/2 inches in length or longer that automatically open by applying pressure to a button or spring in the knife handle.

§ 45-8-331


Any knife that has a blade 4 inches or longer such as a dirk, a dagger or a razor is prohibited.


Concealed weapons are any weapon that is mentioned in section 45-8-316 through section 45-8-318 and 45-8-321 through 45-9-328 which is partially covered by clothing, apparel or any other covering. Except for 45-8-321 through 45-8-328 such as a handgun, a knife with a blade that is 4 or more inches long or covered via clothing or apparel.

Carrying Concealed Weapons:

1 A person carrying or earing a concealed weapon upon their person, such as a dirk, a dagger, pistol, a revolver, even a slingshot or sword cane, billy club, knuckles from any metal or hard substance, knives that have blades longer than 4 inches including razors however not including a safety razor or any other deadly weapon, may be punished by a fine that won’t exceed $500 or by being placed in county jail for no more than six months or both.

§§ 45-8-315, 316

There are, of courses, as always, exceptions to all concealed carry prohibitions as is clearly stated in § 45-8-316. Example, prohibition doesn’t apply for those who reside in outside municipal boundaries or if they are engaged in specific activities upon their own land or premises or business.

Section 45-8-316 does not apply to:

(i) those who reside outside of the boundaries of the city or town or the confines of logging, lumber or mining or railroad areas who are hunting, fishing, or trapping or backpacking or farming or ranching, are carrying said weapons for personal protection.

(j) carrying arms on your own premises or at your home or place of business or

§ 45-8-317

Critical Dimensions:

anything that is less than 4 inches.


All schools are weapon free zones. This doesn’t apply to knives that are less than 4 inches in length that aren’t dirks, switchblades as defined herein or daggers. per § 45-8-361.

Statewide Preemption:

Yes to firearms, no to knives.

This information that is presented as a brief description of the laws and not as any kind of legal advice. aStraightArrow will not and cannot be a legal service provider. The use of the site does not create any sort of client/lawyer relationship. The knife laws are interpreted differently by prosecuting attorneys, enforcement officers, and judges. aStraightArrow suggests you consult legal counsel for further guidance.