Lock Knives and UK Law

A lock knife is not illegal to own. It is illegal to carry in public without a good reason in almost every case, regardless of how short the blade is.

Section 139(2) and (3) of the Criminal Justice Act 1988 exempt only a folding pocketknife with a cutting edge of 3 inches or less from the general offence of carrying a bladed article in public ^[1]. gov.uk guidance is direct on what disqualifies a knife from that exemption. It must not be a lock knife. That means it must not have “a button, spring or catch” holding the blade open ^[2].

This distinction between lock and length causes confusion. A retailer can describe a folding knife as “UK legal” on blade length alone and never mention the locking mechanism. This page works through the rule against specific products people ask about. These are Opinel’s Virobloc, locking multitool blades, friction folders and slipjoints.

This guide covers why locking removes the exemption. It also covers the Opinel Virobloc, multitool locking blades, friction folders and slipjoints. It ends with what a locking knife owner needs to carry one lawfully.

Why does a lock remove the carrying exemption?

The exemption applies to a “folding pocketknife.” A knife that locks open does not meet that description once the blade is released. The statute does not use the word “lock” directly. It uses “folding pocketknife” instead. The accepted interpretation of that phrase is what has excluded locking knives.

CPS guidance records the case-law position that a lock knife “does not come into the category of ‘folding pocketknife’” because it “is not immediately foldable at all times” ^[3]. A knife secured open by a locking mechanism needs a separate step to release the lock before it folds. Examples include a liner lock, a back lock, a lever lock or a ring lock. This takes it outside the exemption at any blade length. It falls back on the ordinary good-reason defence. Full detail is on Good Reason to Carry a Knife: What UK Courts Accept.

Does an Opinel with a Virobloc ring lock count?

Yes. The Virobloc is a rotating steel collar. It locks the blade in the open position until it is manually turned back. This is exactly the kind of mechanism that takes a knife outside the folding pocketknife exemption.

Opinel sells both locking and non-locking versions of its traditional folding knives. A Virobloc-equipped Opinel needs a good reason to carry in public no matter the blade length. Opinel’s non-locking traditional models with a cutting edge of 3 inches or less meet the exemption without one. Checking whether a specific Opinel model has a Virobloc collar matters more than checking its blade length. Do this before assuming it is exempt.

Are locking multitool blades treated differently to a locking pocket knife?

No. The blade itself is treated the same way as any other locking folding knife. A Leatherman, Victorinox or similar multitool with a blade that locks open via a button or lever needs a good reason to carry. This is exactly the same as a single-blade locking folder.

The other tools on a multitool are not bladed or sharply pointed articles in the same sense. Examples include scissors, pliers or a screwdriver. They do not carry the same automatic restriction. It is specifically the knife blade that decides the carrying status. Whether that blade locks is what matters.

Are friction folders and slipjoints legal to carry?

Yes, without a reason if the cutting edge is 3 inches or less. Neither design locks the blade open. A friction folder relies on tension in the pivot to hold the blade open. A slipjoint uses a spring-loaded backspring that can be overcome by hand pressure at any time. Both remain immediately foldable.

The design category matters more than the brand name. The same manufacturer can sell both an exempt and a non-exempt knife side by side, so the locking mechanism has to be checked model by model.

Does Scotland apply the same lock rule?

Yes, this applies in practice. Northern Ireland uses section 139 itself. Section 49(3) of Scotland’s 1995 Act exempts a folding pocketknife whose cutting edge “does not exceed three inches (7.62 centimetres)” ^[4]. The same folding-pocketknife concept sits at the centre of the test. The defence in Scotland is worded as a reasonable excuse or lawful authority ^[4]. Section 172 of the Criminal Justice Act 1988 extends section 139 to Northern Ireland ^[5]. The same exemption and the same good-reason defence apply there.

How do you check whether your own knife locks?

Open the blade fully. Then try to fold it back using only light hand pressure and no button, lever or catch. It is non-locking if the blade folds freely at any point during that motion. It locks if a mechanism has to be released first.

This test matters more than checking a product listing. Retailers do not always describe the locking mechanism accurately or at all. A knife described only by blade length should be treated as unverified until checked by hand or against the manufacturer’s own specification when there is no mention of how the blade is held open. Knives sold under general “pocket knife” or “EDC knife” listings are the most common source of this gap. The seller’s focus is usually the blade steel or handle material rather than the carrying rule.

Does the same lock rule apply to fixed blades?

No. Fixed blades are a separate category. They were never covered by the folding-knife exemption in the first place. A fixed blade has no folding mechanism at all. The lock-versus-non-lock distinction does not apply to it.

Any fixed-blade knife needs a good reason to carry in a public place regardless of length. This includes kitchen knives, hunting knives and craft knives carried outside the home. Section 139(2) exempts only a folding pocketknife. A fixed blade falls outside the exemption by definition ^[1].

What should a lock-knife owner do to carry one lawfully?

Establish and be ready to state the specific good reason before carrying it in public. Only carry it when that reason genuinely applies. Use at work is the first example the statute gives in section 139(5). Religious reasons and national costume are also named ^[1].

Carrying a locking knife “just in case” or for general everyday use does not meet the good-reason test. Full detail on what does and does not count is on Good Reason to Carry a Knife: What UK Courts Accept. A locking knife left at home or in a locked toolbox in a vehicle used only for the relevant work carries far less legal risk than the same knife carried on a person with no immediate task to justify it.

A locking knife carried for a reason that has clearly ended sits in a weaker position. A completed job with no further task planned is one such example. A knife carried with a reason that is still live and current sits in a stronger position.

This is legal information. It is not legal advice. Get advice from a solicitor or Citizens Advice for a specific situation.