The plate camera that reads your AirPods

Introduction

For about a decade, the reason a police camera could photograph your license plate without a warrant came down to one idea any court would nod along to: a car on a public road is already out in the open, so a picture of it isn't a search. Leonardo, the Italian defense conglomerate whose plate-reading gear it says already sits with 4,000 U.S. law enforcement agencies, just patented and started selling a bolt-on that ignores that logic. The add-on reads the Bluetooth leaking off your phone, your AirPods, your smartwatch, and your car's tire-pressure sensor, welds all of it to your plate and a timestamped location, and runs on the number of federal laws written for this exact thing: zero.

No police department has been confirmed to have bought it. The capability still cleared a patent office and a nationwide sales pitch to police without tripping a single oversight requirement, because there is no statute a sale would have to satisfy.

From plates to people

License-plate readers are already everywhere. A 2024 Congressional Research Service report found that nearly 90% of large sheriffs' offices and every police department serving more than a million people run them.

The same report says something jarring for a tool that common: "No specific federal legislative framework exists that governs federal law enforcement use of ALPRs." The Drug Enforcement Administration runs a National License Plate Reader Program built from cameras owned by federal, state, local, and tribal agencies, held together not by a law but by memorandums of understanding.

Then, on June 8, 2026, 404 Media's Joseph Cox published Leonardo's own marketing for a product called ELSAG SignalTrace. It clips onto the existing plate camera rather than replacing it, adds sensors, and starts logging the wireless signals thrown off by the electronics people carry, then matches those to the plate the camera already read. Leonardo US Cyber and Security Solutions is the American arm of Leonardo S.p.A., the Italian state-linked defense conglomerate. Leonardo did not respond to 404 Media's request for comment and has said nothing publicly beyond the marketing.

One thing to clear up: this is not Flock Safety, despite at least one outlet filing SignalTrace under "the Flock addition." Flock, which I've covered here twice, runs a plate-camera network; SignalTrace is a Leonardo product that reads the devices on your body, and no agency has been confirmed to deploy it yet.

What Leonardo put in writing

The product sheet is a single page. SignalTrace "bridges license plate recognition data with sensor-captured device identifiers, such as those from mobile phones, Bluetooth wearables, and vehicle systems, to create a unique, trackable 'electronic fingerprint,'" the document says, across four categories of signal: RFID tags, Bluetooth devices, vehicle components, and Wi-Fi sources, with examples running from key cards and pet microchips to fitness trackers, tire-pressure sensors, and laptops.

It reaches into "rail stations, event venues, and shopping centers," with or without a co-located plate camera. The tagline across the top is blunter than anything I'd write for them: "Identify Suspects Through the Electronic Devices They Carry."

Leonardo's privacy answer sits on the same page: SignalTrace "captures only publicly broadcast device frequency activity. It does not decrypt or store any content from devices or communications." That's true, and it matters: unlike a Stingray, which scoops up call content, SignalTrace only reads the identifiers your devices announce to the open air. The harm lives in the correlation, where that signal gets welded to your plate and a timestamped location, then filed for later. The sheet says those correlations go into what Leonardo calls the Enterprise Operations Center.

If the product sheet is the sales pitch, the patent is where the intent got written down. Leonardo US Cyber and Security Solutions filed U.S. Patent 11,941,716 B2 on January 20, 2023, and the Patent Office granted it on March 26, 2024. The enforceable part, Claim 1, covers capturing electronic signals "emanating from one or more types of electronic devices associated with one or more of (a) a person or (b) one or more transmitting vehicle components." A person, listed first, as a category of its own. The body of the patent goes further, describing sensors placed where a vehicle can't reach ("such as on trains, near railways, around public buildings") to collect signals "from persons away from their vehicle," which makes the car optional and the person the point since the filing date.

Leonardo's general manager said as much when the company announced the patent in May 2024. "The future of LPR advancements is reliant on enhancing LPR data sets with additional information from various electronic devices to find the individuals police are looking for," Jason Laquatra said.

The law that isn't there

You might assume the Supreme Court has this covered. It doesn't. It has spent years extending Fourth Amendment protection to digital location data, most recently in Chatrie v. United States on June 29, 2026, when it ruled that police searched by forcing Google to hand over the location data of every device inside a 150-meter circle. Carpenter v. United States said the same in 2018 about cell-site records from a wireless carrier. Both cases turn on one fact: the government leaned on a company to give up records it already held. SignalTrace removes the company. There's no carrier to subpoena and no Google to serve; a government-run sensor grabs the signal out of the air the instant it's broadcast, and neither ruling decides whether that's a search.

Leonardo's own framing, "only publicly broadcast device frequency activity," is the seed of the government's defense: expose a signal to the open air, the argument goes, and collecting it arguably isn't a search. But broadcasting a Bluetooth identifier isn't a choice you make, it's something your phone does thousands of times a day, which is why newer phones try to randomize those identifiers to resist exactly this kind of tracking. Techdirt's Tim Cushing put the counterargument plainly in June: a car on a public road may have no expectation of privacy, but the personal devices in and around it broadcast data "the public certainly can't" collect the way a government sensor can. Nobody has litigated it yet.

Who Benefits

Leonardo benefits, in the most direct way a company can. The product sheet pitches coverage "with or without co-located LPR cameras," aimed straight at the install base the company claims spans 4,000 agencies: no rip-and-replace, just an upsell onto cameras already on the poles. Plate reading on its own has turned into a crowded business, with Motorola's Vigilant, Rekor, Jenoptik, and others all selling roughly the same thing. Signal fusion is how you stand apart, and being first with a patented, police-facing product in a category with no rules yet is worth far more than being fifth.

Police benefit too, and this is where the vacuum pays off. Because no statute governs what data can ride on an ALPR network, an agency doesn't have to disclose it or get a judge to sign off before its vendor's cameras start reading devices. The upgrade lands at the level of a marketing email, not a public hearing. The federal government has funded this backbone for years: the DEA paid Leonardo $6.9 million from 2017 to 2022 for ALPR maintenance, a contract on the public record. That money predates SignalTrace, which didn't exist yet; it paid for the plate-reading infrastructure the product now upsells into. Expanding what that infrastructure captures costs an agency nothing in oversight, because there's no oversight to spend.

The Bottom Line

The instinct is to relax because no department has confirmed buying it. Read it the other way: the absence of a buyer is what shows how little stands in the way. A tool that reads the phones of everyone near a road went from patent application to finished product marketed to police coast to coast, and nowhere in that chain did anyone have to notify a regulator, open a comment period, clear a legal review, or so much as tell the people whose devices it reads. Leonardo took a category the courts waved through for a decade, plate photos of cars in public, and stretched the same warrant-free status over the electronic signatures of the people in and around those cars, without asking a court or a legislature, because there was no one to ask.

A confirmed purchase would finally leave a record: a council vote, a signed contract, a budget line, a FOIA response, something a reporter or a defense lawyer could pull on. Until that purchase surfaces, the tool sits in the one place the law hasn't reached, fully built and openly for sale.

The only legislative fix in motion doesn't reach it anyway. A bipartisan amendment from Reps. Scott Perry and Chuy García, reported by WIRED in May, would use federal highway funding to choke off plate tracking nationwide, but it was written for the old capability and says nothing about the device signals SignalTrace reads. So the open question is easy to state and hard to answer: does someone write a rule for the phone-reading version before the first agency quietly learns it works, or only after a defendant's lawyer asks how the government knew their client's earbuds were a block from the scene, and the answer turns out to be a sensor nobody voted to switch on?