Every UK Driver Now Risks Prison as Police Gain New Powers Over Car Key Devices

• A new law under the Crime and Policing Act 2026 makes it a criminal offence to own, build, import or supply the devices used to break into keyless cars, carrying an unlimited fine and up to five years in prison.
• Police no longer have to link a device to a specific theft before they search or seize it. Anyone caught holding one now has to show a legitimate reason for owning it.
• Electronic devices were used in 40 percent of UK vehicle thefts in the year to September 2024, rising to 60 percent in London, government figures show.

The Law That Turns a Toolbox Into Evidence

From 29 April 2026, possessing a relay box, signal repeater, signal jammer or key emulator became a criminal offence in England and Wales under the Crime and Policing Act 2026. The Act names four categories of device: relay attack tools that pick up a key fob’s signal and beam it to a car parked metres or streets away, signal amplifiers that boost a weak fob signal through brick walls, jammers that block a car’s own locking signal so it never actually locks, and emulators that copy a genuine key’s code to start the engine without one. Anyone convicted of making, adapting, importing, supplying or simply possessing one of these devices faces an unlimited fine, up to five years in prison, or both.

The offence applies to everyone, not just organised theft gangs. A locksmith carrying a key programmer, a garage running vehicle diagnostics, or a hobbyist with an old signal booster bought for a different purpose could all technically be holding a banned device under the new definitions. Parliament built in a defence: anyone found with a covered device can avoid prosecution by showing they had a legitimate reason to own it, such as approved locksmith or diagnostic work. That defence only applies once police have already stopped and searched someone, which is where the law marks its sharpest break from before.

Why Police No Longer Need Proof First

Before this Act, police needed to connect a device to an actual theft, or to clear intent to steal, before they could act against someone carrying one. In practice that meant officers could stop a car containing a relay box and still struggle to bring a charge unless they caught the occupants in the act of breaking into a vehicle. The new law flips that burden entirely. Once an officer finds a covered device, the person holding it must explain why they have it. If they cannot, the device alone is enough to prosecute, whether or not a theft ever took place.

Thatcham Research, the insurance industry’s vehicle security body, has pushed for this change for years, arguing that relay kits sold online under the guise of “range extenders” or “signal boosters” gave organised gangs a legal grey area to exploit. The National Police Chiefs’ Council backed the shift too, saying stop and search had previously been almost useless against relay theft, as seized devices could not be tied to a specific crime.

The Scale of the Problem Behind the Law

Government analysis found that electronic devices were used in 40 percent of vehicle thefts across England and Wales in the year to September 2024, and in 60 percent of thefts in London specifically. Keyless entry systems, now standard on most cars sold in Britain over the past decade, remain the main target. A relay attack typically takes under 30 seconds to complete, needs two people working roughly ten metres apart, and leaves no broken glass or forced locks behind, which helps explain why recovery rates for stolen vehicles have stayed low even as insurers pay out more each year for theft claims.

Older high specification compact SUVs built between 2016 and 2020 with factory passive entry are among the most targeted, according to Thatcham’s Security Rating research, for two reasons: their low energy key signal is easier to amplify, and strong export demand to Eastern Europe and West Africa keeps resale value high for stolen models. That export pipeline is one reason ports and freight routes are named in the Act’s factsheet as a specific enforcement focus alongside general street policing.

How the Devices Got So Easy to Buy

Relay theft was rare a decade ago, as the equipment needed to pull it off was specialist, expensive and hard to source. That changed as generic radio frequency amplifiers, originally built for entirely legitimate uses such as extending garage door remotes or wireless doorbells, turned out to work almost as well against a car key fob with only minor modification. Online marketplaces sold these units openly for years, often marketed as “signal boosters” with no reference to vehicles at all, which made it difficult for police or retailers to draw a clear legal line between a genuine electronics hobbyist and someone building a theft kit. The new Act closes that gap by banning the finished device itself rather than trying to police the intent behind each sale, and separately places new obligations on online marketplaces to remove listings that clearly describe or market a device for vehicle theft use.

Insurers have watched this shift play out in their own claims data for several years. Vehicle theft claims tied to electronic entry, rather than smashed windows or hot wiring, went from a minor category to the dominant cause of total loss claims on newer cars, which is part of why insurance premiums have climbed even for drivers with a clean record and a car parked on a private driveway.

Protecting Your Own Car Regardless of the Law

The new offence targets people who own theft devices, not the vulnerability in the car itself, so drivers should not assume the law alone makes their vehicle safer overnight. A Faraday pouch or a small steel box for storing key fobs overnight remains the most effective single step, as it blocks the fob’s signal from being picked up at all rather than relying on a thief being caught with the wrong equipment. Parking a vulnerable model somewhere with visible CCTV or under a street light measurably lowers the chance of being targeted, and some manufacturers now offer a free software update that adds motion sensing “sleep mode” to older key fobs, so the fob stops broadcasting a signal after a few minutes of being still. Checking with a franchised dealer whether that update is available for a specific model takes a single phone call and costs nothing.

What to Do if You Own Diagnostic Equipment

Anyone in the motor trade who owns a key programmer, an OBD diagnostic tool with signal functions, or similar equipment should keep proof of purpose on file: trade association membership, business registration, purchase receipts showing the tool’s intended use, or manufacturer documentation. The Motor Ombudsman has advised accredited garages to brief staff on the change so a routine stop does not turn into a lengthy explanation at the roadside. For ordinary drivers, the practical advice has not changed much: a Faraday pouch for your own key fob, which blocks the signal from being read at all, remains one of the cheapest and most effective ways to stop a relay attack before it starts, typically costing under ten pounds against an average vehicle theft claim running into the thousands.

Drivers who spot anything resembling a relay device, jammer or unfamiliar electronic kit near their car, or who are approached by someone selling “signal boosters” for keys, can report it to police on 101 or via Crimestoppers anonymously on 0800 555 111. Under the new law, a report that leads to a search and seizure no longer depends on catching a theft in progress, which the Home Office says was the biggest single gap in enforcement before the Act passed.

The change lands at a moment when vehicle theft remains stubbornly high even as overall recorded crime figures fall, and when the tools used to carry it out have become cheaper and easier to buy online than ever. Whether the burden of proof shift actually cuts theft will depend on how consistently police use the new stop and search power in the months ahead, but for now the legal risk of holding the wrong piece of electronics in the glovebox or boot has changed overnight.

Sources:

• gov.uk: Crime and Policing Act 2026 serious crime factsheet
• gov.uk: Crime and Policing Act 2026 police powers factsheet
• Thatcham Research: Crime and Policing Act 2026