Spring-assisted knives are legal in California. The state’s switchblade ban in Penal Code 17235 specifically excludes knives that require the user to apply thumb pressure to a stud or the blade to start opening it, which is exactly how spring-assisted knives work.1California Legislative Information. California Penal Code 17235 You can own one, buy one, and carry one. What can still get you arrested is how you carry it, where you take it, and whether anyone has modified the opening mechanism.
Why a Spring-Assisted Knife Is Not a Switchblade
Penal Code 17235 defines a switchblade as a pocketknife-style knife with a blade of two or more inches that opens automatically by a button, handle pressure, wrist flick, gravity, or any other mechanical device.1California Legislative Information. California Penal Code 17235 The key word is “automatically.” If pressing a button sends the blade flying open on its own, that’s a switchblade.
The same statute then carves out an exception: a knife that opens with thumb pressure applied directly to the blade or a thumb stud is not a switchblade, so long as the knife has a detent or similar mechanism that creates resistance the user must overcome, or that biases the blade back toward closed.1California Legislative Information. California Penal Code 17235 Spring-assisted knives fit that description. You push a thumb stud or flipper tab to start the blade moving, and the internal spring only takes over once you’ve overcome the initial resistance. The opening starts with you, not with the mechanism.
That distinction reads cleanly on paper and gets messier on the street. Officers don’t always test a knife before making an arrest, and a fast-opening spring-assisted knife can look automatic. If an officer concludes you’re carrying a switchblade, you can be charged under Penal Code 21510, which makes it a misdemeanor to carry, possess in a vehicle, or sell one.2California Legislative Information. California Penal Code 21510 You’d have a strong defense, but you’d still have been arrested to get there.
Open Carry vs. Concealed Carry
California does not prohibit openly carrying a folding knife in public, spring-assisted or otherwise. You can clip one to a pocket, wear it in a belt sheath, or hold it while using it. The problem starts when a folding knife is concealed and the blade is locked open.
Penal Code 16470 defines a dirk or dagger as any knife capable of ready use as a stabbing weapon that could cause great bodily injury or death. For folding knives, the statute adds a critical limit: they qualify only when the blade is exposed and locked into position.3California Legislative Information. California Penal Code 16470 A folding knife carried closed in your pocket is not a dirk or dagger. One locked open and tucked into a jacket or waistband is, and carrying a concealed dirk or dagger under Penal Code 21310 is a wobbler, meaning prosecutors can file it as a misdemeanor or a felony.4California Legislative Information. California Penal Code 21310
The California Supreme Court addressed the locked-blade requirement in People v. Castillolopez (2016). Police found a Swiss Army knife in the defendant’s jacket pocket and he was convicted of carrying a concealed dirk or dagger. The Supreme Court reversed, holding that a blade you can fold closed just by pressing on its back is not “locked into position” and therefore does not meet the statutory definition.5Justia Law. People v. Castillolopez Most spring-assisted knives do have a locking mechanism, so the practical rule is simple. Carry it folded, or wear it openly in a sheath or on a pocket clip. Don’t walk around with the blade locked open and hidden.
Los Angeles and Other Local Rules
Cities can tighten the rules. Los Angeles Municipal Code Section 55.10 prohibits carrying any knife or dagger with a blade of three inches or more in plain view on any public street or public place.6Los Angeles Municipal Code. Los Angeles Municipal Code SEC. 55.10 That creates an awkward situation in LA. State law pushes you toward open carry for anything with a locking blade, and the city then restricts open carry of anything three inches or longer. The workable path in LA is a blade under three inches, clipped visibly to your pocket, folded. Other California cities have their own ordinances, so check locally before traveling with a knife.
Where You Can’t Bring Any Knife
Some locations are off-limits whether or not the knife is otherwise legal.
- Schools (K-12). Penal Code 626.10 bans bringing any knife with a blade longer than two and a half inches, or any folding knife with a locking blade, onto the grounds of any public or private school from kindergarten through 12th grade. It’s a wobbler: up to one year in county jail as a misdemeanor, or 16 months, two years, or three years as a felony.7California Legislative Information. California Penal Code 626.10
- Government buildings. Penal Code 171b prohibits bringing any knife with a fixed blade longer than four inches, or one that can be fixed in an unguarded position, into state or local public buildings where government employees regularly work, including courthouses. Also a wobbler.8California Legislative Information. California Penal Code 171b
- Airport sterile areas. Penal Code 171.5 makes it illegal to possess any knife with a fixed or fixable blade longer than four inches in the sterile area of an airport or passenger vessel terminal. Penalty: up to six months in county jail, up to $1,000, or both. Federal TSA rules separately bar all knives past the checkpoint, regardless of blade length.9California Legislative Information. California Penal Code 171.5
Private property owners and businesses can also prohibit knives on their premises. Refusing to leave after being asked can bring trespass charges.
Modifications That Turn a Legal Knife Illegal
A spring-assisted knife starts legal and can be made illegal. The main risk is tampering with the opening mechanism. Remove or weaken the detent, and the blade can deploy without manual thumb pressure. At that point the knife meets the Penal Code 17235 definition of a switchblade, and carrying or possessing it is a misdemeanor under Penal Code 21510.2California Legislative Information. California Penal Code 21510
Handle design matters too. If a knife’s handle incorporates a metal knuckle guard or striking surface, it may qualify as “metal knuckles” under Penal Code 16920, a separate prohibited weapon category.10California Legislative Information. California Penal Code 16920 Novelty trench-knife designs that pair a blade with brass-knuckle-style grips fall into that trap.
Buying and Shipping to California
The Federal Switchblade Act prohibits shipping switchblades in interstate commerce and restricts their importation. It defines a switchblade as a knife whose blade opens automatically by pressing a button on the handle, or by gravity or inertia.11Office of the Law Revision Counsel. 15 USC 1241 Since 2009, the law has carried a specific exception for spring-assisted knives: a knife with a spring or detent that biases the blade toward closure and requires hand, wrist, or arm force applied to the blade to overcome that bias is not a switchblade under federal law.12GovInfo. 15 USC 1244 – Exceptions
You can buy a spring-assisted knife online and have it shipped to a California address. It still has to comply with California law once it arrives, but the shipment itself is permitted. Retailers and private sellers inside California can legally sell them, because the Penal Code 21510 sale prohibition targets switchblades, not spring-assisted knives.2California Legislative Information. California Penal Code 21510 Local jurisdictions may have their own rules tied to blade length, so sellers operating in multiple cities should check municipal codes.
Penalties If Something Goes Wrong
The knife itself won’t get you charged. Related offenses will.
- Switchblade possession or carry (PC 21510). If a knife is misidentified as a switchblade or has been modified to function like one, the charge is a misdemeanor: up to six months in county jail, up to $1,000, or both.13California Legislative Information. California Penal Code 19
- Concealed dirk or dagger (PC 21310). Carrying a spring-assisted knife locked open and hidden on your person is a wobbler. As a misdemeanor, up to one year in county jail. As a felony, 16 months, two years, or three years.14California Legislative Information. California Penal Code 1170h
- Knife on school grounds (PC 626.10). A wobbler, with the same misdemeanor and felony ranges.7California Legislative Information. California Penal Code 626.10
- Carrying a deadly weapon with intent to assault (PC 17500). A misdemeanor: up to six months in jail and a $1,000 fine.15California Legislative Information. California Penal Code 17500
How to Stay Clear of Trouble
The law is on your side if you carry sensibly. Keep the blade folded when you’re not using the knife. If it has a pocket clip, use it so the knife reads as visible rather than hidden. Stay out of schools, government buildings, and airport sterile areas. If you’re stopped by police, don’t reach for the knife or offer to demonstrate how fast it opens. Tell the officer calmly that it’s a spring-assisted knife with a thumb stud, and let the mechanism show itself if asked.
In Los Angeles, keep the blade under three inches so the city’s open-carry rule doesn’t catch you. And if you’ve adjusted a spring or detent, test it honestly. A knife that used to need thumb pressure and now flips open with a wrist flick has crossed the line from legal spring-assisted opener to illegal switchblade, no matter what the manufacturer sold it as.