Are Butterfly Knives Illegal in the UK? The Full Legal Picture

What Is a Butterfly Knife?

A butterfly knife — properly known as a balisong — is a folding pocketknife with two handles that counter-rotate around the tang, concealing the blade when closed. Flicked open with a practiced wrist motion, the handles swing outward and lock the blade into place. The design originated in the Philippines and became a fixture of martial arts flow, flair tricks, and, eventually, action films and video games, which is exactly why so many people search for one online without realising what UK law says about them.

That cinematic reputation is part of the problem from a legal standpoint. Parliament has treated balisongs as a “flick-style” weapon since the late 1980s, grouping them with switchblades and gravity knives under legislation aimed at rapid-deployment blades rather than ordinary pocketknives.

The Short Answer

For a wider view of how balisongs sit alongside every other restricted blade type, our complete guide to UK knife law breaks down the full legislative landscape in one place.

The Legislation Behind the Ban

The core restriction traces back to the Criminal Justice Act 1988 (Section 1) and its associated Order, which named specific knife types as illegal to manufacture, sell, or hire out. Butterfly knives appear explicitly on that list, alongside disguised knives, push daggers, and other blades that Parliament judged had no legitimate everyday purpose.

The Restriction of Offensive Weapons Act 1959 and later the Offensive Weapons Act 2019 reinforced and expanded these controls, closing loopholes around online sales, remote purchases, and delivery to private addresses. The 2019 Act specifically targeted the practice of ordering banned blades online and having them delivered to a home address without age or identity verification — a route that had previously let balisongs slip through.

Separately, the Criminal Justice Act 1988 (Offensive Weapons) Order 1988 is the actual statutory instrument that lists balisong knives by name, alongside butterfly knives’ close cousins such as flick knives and gravity knives. If you want the mechanics of how flick-style knives are treated under the same order, our breakdown of flick knife UK law covers the parallel restrictions in detail.

Is Owning a Butterfly Knife Illegal?

This is where the law gets nuanced. The 1988 Order bans manufacturing, selling, hiring, offering for sale or hire, exposing for sale or hire, or lending a butterfly knife. It does not, on its own wording, criminalise the bare act of quietly owning one that you already had before these rules were formalised, or one that was gifted to you privately without a sale taking place.

In practice, though, that theoretical distinction rarely matters. You cannot legally have acquired the knife through any normal retail channel since the 1980s, you cannot legally show it to friends, and the moment it leaves your house — even briefly, even in a bag in the boot of your car — you are carrying a bladed article in public, which is a separate and very real offence under Section 139 of the Criminal Justice Act 1988.

Carrying a Butterfly Knife in Public

Even setting the balisong-specific ban aside for a moment, UK law is separately strict about carrying any knife in a public place. Section 139 of the Criminal Justice Act 1988 makes it an offence to carry a bladed or sharply pointed article in public without “good reason or lawful authority” — a defence that covers things like a chef travelling to work with kitchen knives, not a folding blade tucked into a jacket pocket.

Because a butterfly knife is banned outright, there’s no good-reason defence available to you the way there might be for an ordinary locking pocketknife under 3 inches. If you’re unclear on how that everyday-carry exemption works for legal folding knives, our guide on whether it’s legal to carry a pocket knife in the UK lays out the blade-length and “good reason” rules in plain terms — and it’s worth reading precisely because it shows how differently the law treats a banned weapon versus a legal tool.

For context on where the length thresholds and locking-blade rules come from for ordinary knives, see our explainer on legal knife length in the UK.

Buying and Importing Butterfly Knives

Retailers based in the UK cannot legally list, advertise, or sell genuine butterfly knives — that’s the manufacture-and-sale side of the 1988 Order in action. What trips up a lot of buyers is assuming that ordering from an overseas website sidesteps the ban. It doesn’t.

UK Border Force treats an imported balisong the same way it treats a domestic sale: as a prohibited weapon. Customs routinely intercepts and seizes balisong shipments, and the buyer — not just the seller — can face prosecution for importing a banned weapon, on top of losing the item and any money paid for it. The Offensive Weapons Act 2019 also introduced tighter rules around remote sales generally, specifically to stop banned blades reaching UK addresses via online marketplaces and international sellers.

Balisong Trainers: The Legal Loophole That Actually Works

The one genuinely reliable way to enjoy balisong flipping in the UK is a trainer — a knife-shaped tool built for flipping tricks that has no sharpened edge and, in most designs, no edge at all. Because the legal definition of a “knife” for the purposes of the 1988 Order hinges on the article having a blade capable of cutting, a trainer with a rounded, blunt, unsharpened profile falls outside the ban.

This is the same reasoning that underpins the wider balisong hobbyist and flipping community, which has grown almost entirely around trainer models rather than live blades — even in countries where owning a bladed balisong is legal, trainers are preferred for safety during trick practice. If you’re weighing up whether a specific model counts as legal, our detailed piece on whether balisongs are legal in the UK goes further into the blunt-blade distinction and the small number of edge cases that catch buyers out.

How Balisongs Compare to Other Banned or Restricted Knives

Butterfly knives don’t sit alone on the list of restricted weapons. It helps to see where they fall relative to other blades people commonly ask about, since the legal reasoning — and the loopholes — often overlap.

Karambits sit in a particularly confusing middle ground for a lot of readers, since the blade shape looks aggressive but isn’t itself named in legislation. We cover that distinction fully in our guide on whether karambits are legal in the UK. Flick knives, meanwhile, are banned through the exact same clause of the same Order as balisongs, so anyone who understands one restriction largely understands the other — our dedicated page on flick knife UK law is a useful side-by-side read.

Penalties for Illegal Possession or Carrying

The consequences scale with what you were actually caught doing, and courts do treat balisongs seriously given their explicit banned status.

Even a first offence with no aggravating factors can result in a criminal record, which has knock-on effects for employment, travel, and visa applications well beyond the immediate fine or sentence. Age is not a mitigating factor in the way many assume — police and courts apply these rules to under-18s carrying knives with equal, sometimes greater, seriousness.

Legal Alternatives If You Want the Balisong Experience

If your interest is genuinely the trick-flipping hobby rather than the knife as a tool, a trainer gives you essentially the entire experience — the same weight distribution, the same handle rotation, the same muscle memory — without any legal exposure at all.

Common Myths About Butterfly Knives and UK Law, Debunked

“It’s legal if the blade is under 3 inches”

The 3-inch, non-locking exemption applies to ordinary folding knives under Section 139. It does not override the separate, explicit ban on balisongs under the 1988 Order — blade length is irrelevant once a knife is named on the prohibited list.

“It’s fine if I only use it at home”

Using or displaying it at home doesn’t itself trigger the carrying offence, but you still can’t have legally bought, sold, or been lent a functioning one, and moving it anywhere outside your property is a separate risk.

“Antique or vintage balisongs are exempt”

There’s no blanket antique exemption for balisongs the way there sometimes is for certain historic bladed items. Age of manufacture doesn’t change the weapon’s legal classification.

“Customs won’t notice a small package”

Border Force uses X-ray screening on a large proportion of international parcels specifically to catch prohibited weapons, and balisong seizures are common enough that this isn’t a reliable assumption to make.

Frequently Asked Questions