Balisongs are legal in Maryland. State law treats a butterfly knife as a penknife, which is excluded from the list of dangerous weapons, so you can own one and carry it either openly or concealed. The limits worth knowing sit outside that general rule: you cannot bring one onto public school property, some local governments (notably Baltimore) restrict knives by blade length, and federal law classifies balisongs as switchblades for purposes of interstate shipping and the mail.
Why State Law Allows It
Maryland Criminal Law § 4-101 lists the items it treats as weapons: dirk knives, bowie knives, switchblade knives, star knives, sandclubs, metal knuckles, razors, and nunchaku. The same section carves out an exception for a “penknife without a switchblade.”1Maryland General Assembly. Maryland Code Criminal Law 4-101 – Dangerous Weapons The statute never defines “penknife,” so the definition comes from the courts.
In Bacon v. State, 322 Md. 140 (1991), the Maryland Court of Appeals held that “[p]enknives today are commonly considered to encompass any knife with the blade folding into the handle, some very large.”2vLex United States. Bacon v. State, 586 A.2d 18 Size doesn’t matter under that test, and neither does any locking mechanism.
A balisong works by rotating two handles around the blade’s tang until the blade is enclosed between them. The blade folds into the handle, which is the entire test. That puts a balisong inside the penknife exception and outside the statutory definition of a weapon.
Carrying Openly or Concealed
Section 4-101 does two things. It bans carrying a dangerous weapon concealed on or about the person, and it bans carrying one openly with the intent to injure someone unlawfully.1Maryland General Assembly. Maryland Code Criminal Law 4-101 – Dangerous Weapons Both prohibitions depend on the item being a “weapon” as the statute defines that word. A balisong isn’t one, so neither prohibition applies.
The appearance of the knife doesn’t change the analysis. A balisong looks unusual and flips open in a way that draws attention, but the legal question is mechanical: does the blade fold into the handle? It does, and the penknife exception controls.
Public Schools Are Off-Limits
Maryland Criminal Law § 4-102 bans all knives on public school property. The statute prohibits carrying or possessing a firearm, knife, or deadly weapon of any kind at a school.3Maryland General Assembly. Maryland Criminal Law Code Section 4-102 – Deadly Weapons on School Property The word “knife” stands on its own in that list, separate from “deadly weapon,” so the penknife exception from § 4-101 doesn’t rescue a balisong here. A balisong on school grounds is a crime regardless of how it is classified for street carry.
A violation is a misdemeanor punishable by up to three years in prison, a fine of up to $1,000, or both.3Maryland General Assembly. Maryland Criminal Law Code Section 4-102 – Deadly Weapons on School Property The narrow carve-outs cover law enforcement officers, school security, organized educational shooting activities, and historical demonstrations held with a principal’s written invitation.
Local Ordinances Can Be Stricter
Maryland does not preempt local knife laws. Counties and cities can pass restrictions tighter than § 4-101, and several have. A balisong that is lawful under state law can still violate a local ordinance.
Baltimore City’s Three-Inch Rule
Baltimore is the clearest example. Under Baltimore City Code § 59-23, a “dangerous knife” includes any knife with a blade longer than three inches, along with bowie knives, dirk knives, gravity knives, star knives, straight razors, and switchblades. No one may sell, give, or transfer a dangerous knife to anyone under 21, and retail displays face their own restrictions.4City of Baltimore Law Library. Baltimore City Code Article 19 – Section 59-23 – Dangerous Knives A violation is a misdemeanor carrying up to 12 months in jail, a fine of up to $1,000, or both. If your balisong has a blade longer than three inches, Baltimore treats it as a dangerous knife.
Elsewhere in the State
Several Maryland counties restrict minors from carrying dangerous weapons during overnight hours, and other localities may impose blade-length limits or additional rules. Because there is no statewide preemption, the only reliable step is to check the municipal or county code for the place you plan to carry.
Federal Rules on Shipping, Mail, and Air Travel
Federal law takes a different view of balisongs than Maryland does. A U.S. Customs regulation lists “Balisong” and “butterfly” knives inside the definition of switchblade, covering any knife that opens “by operation of inertia, gravity, or both.”5eCFR. 19 CFR Part 12 – Switchblade Knives That classification shapes how a balisong can be bought, shipped, and transported.
The Federal Switchblade Act (15 U.S.C. §§ 1241–1245) prohibits knowingly introducing switchblade knives into interstate commerce. Buying, selling, or shipping a balisong entirely within Maryland is unaffected, but ordering one from an out-of-state retailer or sending one across state lines raises a federal issue.
Under 18 U.S.C. § 1716, knives that open by inertia or gravity are nonmailable. A balisong cannot go through the U.S. Postal Service, and a knowing violation carries a fine, up to one year in prison, or both.6Office of the Law Revision Counsel. 18 U.S. Code 1716 – Injurious Articles as Nonmailable Private carriers like UPS and FedEx are generally exempt from the postal restriction under the Federal Switchblade Act, though each carrier sets its own policies.
For flying, the TSA prohibits all knives in carry-on luggage apart from rounded butter knives and plastic cutlery. A balisong may go in checked baggage if it is sheathed or securely wrapped to protect baggage handlers.7Transportation Security Administration. Sharp Objects The checkpoint officer has final discretion, and the knife laws at your destination may be very different from Maryland’s.