Yes, butterfly knives are illegal in California in every way that matters to most people. State law classifies balisongs as switchblades, and Penal Code 21510 makes it a misdemeanor to carry one on your person, keep one in a vehicle in a public place, or sell, loan, or give one to another person. The statute stops short of banning private possession inside your home, but because you cannot legally buy, receive, or transport one in the state, that gap is narrower than it sounds.
Why a Balisong Counts as a Switchblade
Penal Code 17235 defines a switchblade as a knife resembling a pocketknife, with a blade of two or more inches, that can be released by a button, pressure on the handle, a flip of the wrist, gravity, or any other mechanism.1California Legislative Information. California Penal Code 17235 The statute never uses the words “butterfly knife” or “balisong.” The link was drawn by a California appeals court in People ex rel. Mautner v. Quattrone (1989), which held that butterfly knives fit the definition because their handles flip open with a wrist motion.2Justia. CALCRIM No. 2502 – Possession of Switchblade Knife
PC 17235 does carve out one category: knives that open by thumb pressure on the blade or a thumb stud, provided the blade has a detent or spring resisting the opening. That exception rescues most standard folding knives. It does nothing for a balisong, which opens by swinging two handles rather than pushing a stud.1California Legislative Information. California Penal Code 17235
What Penal Code 21510 Actually Bans
PC 21510 lists three prohibited acts involving a switchblade with a blade of two or more inches:3California Legislative Information. California Penal Code 21510
- Possessing one in the driver or passenger area of a motor vehicle in a public place or a place open to the public.
- Carrying one on your person, whether openly or concealed, anywhere.
- Selling, loaning, transferring, or giving one to another person.
Each violation is a misdemeanor.
Keeping One at Home
The statute is narrower than most people assume. Those three acts are the entire list. Private possession inside your own home is not among them, and PC 21510 contains no blanket ownership ban. That technical gap sounds like a loophole, but it closes quickly in practice. You cannot buy a balisong from any California seller, you cannot legally receive one shipped into the state, and you cannot carry it out of your house to anywhere else. Home possession sits inside a wall with no legal door in.
Where Penalties Get Worse
Two locations carry harsher consequences than the general carry ban.
Penal Code 171b makes it a crime to bring any weapon described in PC 17235 into a state or local government building, or into any meeting required by law to be open to the public. Courthouses, city halls, and legislative hearings fall under this. The offense is a wobbler: prosecutors can charge it as a misdemeanor with up to a year in county jail, or as a felony with state prison time.4California Legislative Information. California Penal Code 171b
Penal Code 626.10 covers schools. At K-12 campuses, public or private, the statute prohibits knives with blades longer than two and a half inches, folding knives with a locking blade, and a list of other weapons. A butterfly knife fails on multiple grounds. Bringing one onto K-12 grounds is a wobbler carrying up to a year in county jail or state prison.5California Legislative Information. California Penal Code 626.10 At colleges and universities, subdivision (b) of the same statute is narrower — it targets dirks, daggers, ice picks, and fixed-blade knives longer than two and a half inches, and a balisong doesn’t have a fixed blade. The general PC 21510 carry ban still applies on college campuses, so bringing one is still illegal.
Buying, Selling, and Shipping
PC 21510(c) bans selling, offering for sale, loaning, or giving a butterfly knife to anyone. Retailers, pawn shops, and private sellers are all covered. No dealer license or permit makes commercial sales legal in California.3California Legislative Information. California Penal Code 21510
Ordering online from an out-of-state or overseas seller runs into federal law on top of the state ban. The Switchblade Knife Act of 1958 makes it a federal crime to introduce a switchblade into interstate commerce, with penalties of up to $2,000 in fines, five years in prison, or both.6GovInfo. 15 U.S.C. Chapter 29 – Manufacture, Transportation, or Distribution of Switchblade Knives U.S. Customs and Border Protection treats switchblades as prohibited imports subject to seizure.7U.S. Customs and Border Protection. Traveling With a Personal Knife/Switchblade/Sword Into the United States
Penalties If You’re Caught
Under PC 21510, a violation is punishable by up to six months in county jail, a fine of up to $1,000, or both — the standard misdemeanor penalties in Penal Code 19.8California Legislative Information. California Penal Code 19 PC 171b and PC 626.10 both go up to a year in county jail as misdemeanors, with felony state prison time on the table.
The knife itself will be confiscated and courts routinely order it destroyed. A conviction creates a criminal record, and a misdemeanor weapons charge can quietly do more damage than the sentence: it shows up on background checks, it can affect firearm ownership rights, and it carries serious immigration consequences for non-citizens. If a butterfly knife turns up during another offense, expect stacked charges and sentencing enhancements.
Trainer Butterfly Knives
Balisong trainers with dull or unsharpened blades are popular for practicing flipping tricks, and California law does not address them directly. The switchblade definition in PC 17235 focuses on the opening mechanism, not sharpness, so an object that opens like a butterfly knife could be treated as one even if it can’t cut. On the other hand, many trainers have no real blade at all — just flat metal or plastic shaped like one — which weakens the argument that they’re a “knife” in any meaningful sense.
No published California court decision draws a clean line. The cautious reading is that any trainer with a metal blade-shaped component measuring two inches or more sits in a legal gray area. Officers can confiscate items they believe are switchblades, and arguing the distinction at a traffic stop is not a good position to be in.
Air Travel and Checked Luggage
TSA rules bar all knives from carry-on bags. A butterfly knife can technically go in checked luggage under TSA’s general policy allowing knives in checked bags when sheathed or securely wrapped.9Transportation Security Administration. Sharp Objects Getting through the checkpoint is not the same as being legal on the ground. If you land at LAX or SFO with a balisong in your checked bag, you are in possession of a prohibited switchblade the moment you pick up your luggage. TSA lets it fly. California doesn’t let you carry it out of the terminal.