Yes, butterfly knives are illegal to own in the UK. Since 2019, simply having one in your home, car, or anywhere else private has been a criminal offence, on top of the older bans on carrying, selling, or importing them. The rule applies across England, Wales, Scotland, and Northern Ireland, and it applies whether the blade is sharp or blunt.
Why Ownership Itself Is a Crime
Butterfly knives, also called balisongs, sit on the list of prohibited offensive weapons under the Criminal Justice Act 1988. For decades, that list made it illegal to sell, hire, lend, give away, or carry one in public, but private possession sat in a grey area. The Offensive Weapons Act 2019 closed that gap by inserting a new offence, Section 141(1A), into the 1988 Act. It is now a criminal offence to possess a prohibited weapon in private.1Legislation.gov.uk. Offensive Weapons Act 2019 – Section 46
“Private” here means exactly what it sounds like: your home, a garage, a locked car, a storage unit, a friend’s flat. There is no location in the UK where a private citizen can lawfully keep a butterfly knife without a specific statutory defence, which almost no one has.
Unlike the general offence of carrying a bladed article in public, where you can raise a “good reason” defence, no equivalent exists for possessing a prohibited weapon. Intent to use it, sentimental value, keeping it locked away, having owned it for years — none of that is a defence on its own.
What the Law Counts as a Butterfly Knife
The statutory definition describes a blade enclosed by its handle, where the handle splits down the middle to reveal the blade without a spring or mechanical device.2Legislation.gov.uk. The Criminal Justice Act 1988 (Offensive Weapons) Order 1988 Schedule It is the split, counter-rotating handle mechanism that defines the weapon in law, not the sharpness of what is inside.
That distinction matters because blunt “trainer” balisongs are widely sold on overseas websites as flipping toys. The legislation refers to a “blade enclosed by its handle” and does not carve out an exemption for unsharpened versions. Official government guidance lists the butterfly knife as banned without any note about trainers.3GOV.UK. Selling, Buying and Carrying Knives and Weapons No published court decision has held that a completely blunt trainer sits outside the ban, and Border Force officers routinely seize them at customs. Treating a trainer as legal is a gamble the law does not clearly support. If you are unsure about a particular item, the government’s advice is to contact your local police or seek legal advice.
What You Face for Owning One
Penalties for private possession depend on which part of the UK you are in.
- In England and Wales, private possession under Section 141(1A) is a summary offence carrying up to 51 weeks’ imprisonment, a fine, or both.1Legislation.gov.uk. Offensive Weapons Act 2019 – Section 46
- In Scotland, private possession is summary only, with a maximum of six months’ imprisonment.1Legislation.gov.uk. Offensive Weapons Act 2019 – Section 46
- In Northern Ireland, the possession offence under Section 141 is triable either way and carries up to four years’ imprisonment on indictment.4Legislation.gov.uk. Criminal Justice Act 1988 – Section 141
A figure often quoted online is four years’ imprisonment for butterfly knife possession. In England and Wales, that ceiling applies to the separate offence of carrying an offensive weapon in a public place under Section 1 of the Prevention of Crime Act 1953, tried on indictment in the Crown Court.5The Crown Prosecution Service. Knife and Other Weapons Offences Private possession alone in England and Wales tops out at 51 weeks.
The Narrow Defences
Section 141 provides a specific, closed list of statutory defences for possession of a prohibited weapon. If a prosecution is brought, you would have to prove that the knife was possessed for one of these purposes:
- genuine historical importance
- operating, or acting on behalf of, a non-profit museum or gallery
- educational use
- theatrical performances, rehearsals, or film or television production
- a sporting activity or historical re-enactment
- religious ceremonies
These defences are set out in Section 141 of the Criminal Justice Act 1988.4Legislation.gov.uk. Criminal Justice Act 1988 – Section 141 A separate exemption covers antique weapons manufactured more than 100 years before the date of the alleged offence.2Legislation.gov.uk. The Criminal Justice Act 1988 (Offensive Weapons) Order 1988 Schedule A butterfly knife predating the 1920s would need proper authentication, and even then the exemption protects possession rather than carrying it in public.
These are heavily fact-specific and would need to be proven by the person charged. None of them adds up to a general right to own a butterfly knife for personal interest, collecting, or self-defence.
If You Already Own One
If you have a butterfly knife sitting in a drawer, whether it was bought abroad years ago, inherited, or forgotten about, you are committing an offence by keeping it. The sooner you deal with it, the better.
The government ran a formal surrender and compensation scheme between December 2020 and March 2021. During that window, owners could hand in prohibited weapons and claim a small payment, set at £9 for a butterfly knife.6GOV.UK. Offensive Weapons Act 2019 – Surrender and Compensation Scheme Guidance That window has closed. You can still surrender the knife to your local police station, but no payment is available.
Before you go, call the station and ask how they want the weapon packaged and transported. Officers deal with surrendered items regularly and will give you clear instructions. Walking in unannounced with an unpackaged knife is exactly what you want to avoid.
Buying, Selling, or Bringing One In
Because these questions usually come up alongside ownership: selling, hiring, lending, or giving a butterfly knife to anyone is a separate offence under Section 141(1) of the Criminal Justice Act 1988, whether or not money changes hands. In England and Wales, it carries up to six months’ imprisonment, a fine up to level 5 on the standard scale, or both.4Legislation.gov.uk. Criminal Justice Act 1988 – Section 141 You cannot lawfully pass a butterfly knife on to a friend, sell it at a car boot sale, or list it online.
Importing one is also a separate offence, governed by the Customs and Excise Management Act 1979 through the prohibited weapons schedule.2Legislation.gov.uk. The Criminal Justice Act 1988 (Offensive Weapons) Order 1988 Schedule Ordering a butterfly knife from an overseas retailer and having it shipped to a UK address exposes you to criminal liability even if Border Force intercepts the parcel and it never reaches you.
The short version, then, is that every route by which a butterfly knife might come into your hands, stay in your hands, or leave your hands is prohibited by UK law. Ownership is not the exception. It is now one of the clearest offences on the list.