Colorado knife laws let you own and openly carry almost any knife, but concealing a blade longer than 3.5 inches is a class 1 misdemeanor unless an exception applies, ballistic knives are banned outright, and schools and federal buildings are off-limits regardless of blade size.1Justia. Colorado Revised Statutes Section 18-12-105 – Unlawfully Carrying a Concealed Weapon – Unlawful Possession of Weapons Cities including Denver, Boulder, Aurora, Lakewood, and Colorado Springs layer stricter rules on top of state law, so a knife that’s legal in one town can get you cited in the next.
Knives You Can’t Own at All
Colorado’s short list of “illegal weapons” includes blackjacks, gas guns, metallic knuckles, and ballistic knives.2Justia. Colorado Revised Statutes Section 18-12-102 – Possessing a Dangerous or Illegal Weapon – Affirmative Defense – Definition The ballistic knife is the only true knife on that list. It’s defined as any knife with a blade that shoots out of the handle using a spring-loaded device or an explosive charge.3Colorado Bureau of Investigation. Colorado Revised Statutes 18-12-101 – Definitions Knowingly possessing one is a class 1 misdemeanor anywhere, concealed or not.
Switchblades and gravity knives used to sit on that same list. The legislature removed them in 2017 through SB17-008, so both are now legal to own and carry under state law.4Colorado General Assembly. SB17-008 Legalize Gravity Knives and Switchblades Assisted-opening knives were never restricted. The difference between the two matters in cities that still ban automatics: a switchblade deploys entirely from a button press, while an assisted opener requires you to physically start the blade moving with a thumb stud or flipper before the spring takes over.
The 3.5-Inch Rule for Concealed Carry
Open carry is broadly legal in Colorado. The trouble starts when you hide the blade. State law defines a “knife” for concealed-carry purposes as any dagger, dirk, knife, or stiletto with a blade over 3.5 inches, plus any other dangerous instrument capable of inflicting cutting, stabbing, or tearing wounds.5Justia. Colorado Revised Statutes Section 18-12-101 – Peace Officer Affirmative Defense – Definitions The catch-all in that second half means even a shorter blade could qualify if it’s being carried as a weapon.
A knife counts as concealed when it’s placed out of sight so it isn’t visible on ordinary observation. Pockets, waistbands under clothing, and bags on your person all qualify. A blade clipped visibly to the outside of your pocket or worn openly in a belt sheath is not concealed.6Colorado Bureau of Investigation. Colorado Revised Statutes 18-12-105 – Unlawfully Carrying a Concealed Weapon If you’re near the length limit and want to carry the knife on you, keeping it visible sidesteps the problem entirely.
When the Concealment Rule Doesn’t Apply
The statute carves out three situations where you can conceal a blade over 3.5 inches:
- In your own home, at your place of business, or on property you own or control.1Justia. Colorado Revised Statutes Section 18-12-105 – Unlawfully Carrying a Concealed Weapon – Unlawful Possession of Weapons
- In a private car or other private vehicle, if the knife is there for lawful protection of yourself, another person, or property while traveling.1Justia. Colorado Revised Statutes Section 18-12-105 – Unlawfully Carrying a Concealed Weapon – Unlawful Possession of Weapons
- When the knife is used for hunting or fishing. Sporting knives are excluded from the statutory definition of “knife” entirely, but this operates as an affirmative defense.5Justia. Colorado Revised Statutes Section 18-12-101 – Peace Officer Affirmative Defense – Definitions
The affirmative-defense point is worth pausing on. It doesn’t stop an officer from citing or arresting you. It means you can raise the defense in court and carry the burden of showing the knife was genuinely for hunting or fishing. A fillet knife in a tackle box next to your rod and license reads very differently from the same knife loose in a jacket pocket at a gas station.
Places You Can’t Carry Regardless of Blade Size
Schools, Colleges, and Universities
Bringing a deadly weapon other than a firearm onto the grounds of any public or private elementary, middle, junior high, high, or vocational school, or any college, university, or seminary, is a class 6 felony in Colorado.7Justia. Colorado Revised Statutes Section 18-12-105.5 – Unlawfully Carrying a Weapon – School, College, or University Grounds “Deadly weapon” here covers any knife or instrument used or intended to be used in a way capable of producing death or serious bodily injury.8Justia. Colorado Revised Statutes Section 18-1-901 – Definitions A forgotten pocketknife in a backpack can fall inside that definition depending on the circumstances, and school-grounds enforcement is strict.
Narrow exceptions cover authorized educational demonstrations, employees whose job duties require a blade, and approved extracurricular or athletic activities.7Justia. Colorado Revised Statutes Section 18-12-105.5 – Unlawfully Carrying a Weapon – School, College, or University Grounds Anything outside those, leave in the car or at home.
Federal Buildings
Federal facilities in Colorado follow federal law, not state knife law. Under 18 U.S.C. ยง 930, bringing a dangerous weapon into a federal facility is punishable by up to one year in prison. Pocketknives with blades under 2.5 inches are specifically exempt, meaning the federal threshold is a full inch lower than Colorado’s concealed-carry limit.9Office of the Law Revision Counsel. 18 USC 930 – Possession of Firearms and Dangerous Weapons in Federal Facilities Federal courthouses raise the maximum to two years. The Interagency Security Committee standard governing federal facility screening also bars any bladed device with a blade over 2.5 inches and prohibits razor-type blades like box cutters at any length.10National Archives. Items Prohibited in Federal Facilities – An ISC Standard 2022 Edition Post offices, Social Security offices, VA clinics, and federal courthouses all fall under these rules.
Airports
TSA does not allow knives in carry-on bags. Knives can go in checked luggage but must be sheathed or securely wrapped, and the final decision at the checkpoint rests with the TSA officer.11Transportation Security Administration. Knives
City Rules That Override State Permissiveness
Colorado does not broadly preempt local knife regulation. The one statewide preemption for knives protects carry inside a private vehicle: a knife in your car for lawful protection or for hunting is legal statewide even if the city you’re driving through has stricter rules.12American Knife and Tool Institute. Colorado Knife Laws Step out of the car and onto the sidewalk, and municipal law takes over.
The differences add up quickly. Denver bans automatic knives outright under its municipal code, despite the state’s 2017 legalization. Aurora and Lakewood keep their own switchblade bans in place. Boulder and Colorado Springs restrict concealed carry of any knife, not only blades over 3.5 inches, and both cities prohibit displaying a knife in a way that threatens or alarms others.13American Knife and Tool Institute. Preemption Law and Knives The only reliable way to know what’s allowed where you actually are is to check that city’s municipal code before carrying.
What a Violation Costs
- Concealed carry of a knife over 3.5 inches is a class 1 misdemeanor: up to 364 days in jail and a fine of up to $1,000.1Justia. Colorado Revised Statutes Section 18-12-105 – Unlawfully Carrying a Concealed Weapon – Unlawful Possession of Weapons
- Possessing a ballistic knife or other illegal weapon is also a class 1 misdemeanor with the same range.2Justia. Colorado Revised Statutes Section 18-12-102 – Possessing a Dangerous or Illegal Weapon – Affirmative Defense – Definition
- Carrying a deadly weapon on school grounds is a class 6 felony: one to 18 months in prison, a fine between $1,000 and $100,000, and one year of mandatory parole after release.14Justia. Colorado Revised Statutes Section 18-1.3-401 – Felonies – Classification – Presumptive Penalties
The gap between the misdemeanor charges and the school-grounds felony is where the real risk sits. A misdemeanor is a criminal record and often gets pleaded down. A felony conviction shows up on background checks for life and can affect employment, housing, and firearm rights.