License plate cameras will soon track phones, wearables, infotainment, and even your pets

Those license plate cameras hanging over highways and intersections are no longer just reading plates.

New technology now allows some of them to detect the electronic devices traveling with you: your phone, smartwatch, Bluetooth headphones, infotainment system, AirTags, and even some pet trackers.

Collect enough data points, and it becomes possible to identify where someone works, where they live, and who they regularly travel with.

In other words, the goal is no longer simply to identify your car. It’s to identify you. And most drivers have no idea this capability already exists.

Easy reader

Most Americans are familiar with Automatic License Plate Readers. Police departments, toll authorities, and private companies have used them for years. They photograph license plates, log the time and location, and store that information in massive databases.

These systems were originally sold as tools to find stolen vehicles and assist in Amber Alerts. But the databases have grown enormously, storing billions of scans and increasingly being used for purposes far beyond their original mission. Civil liberties groups have been raising concerns about that expansion for years.

According to Flock Safety, one of the largest providers of these systems, its cameras capture multiple frames of video and use motion detection to identify vehicles. The company says it does not use facial recognition technology and that its cameras are not designed to identify individuals.

Yet that distinction is becoming increasingly difficult to maintain.

ALPR cameras use optical character recognition technology to convert license plate images into digital text and compare that information against databases of vehicles of interest. Increasingly, however, the cameras are doing much more than simply reading plates.

Electronic fingerprint

Now, here’s where things get serious.

A defense contractor called Leonardo has been promoting a system called SignalTrace. It turns license plate cameras into advanced vehicle-tracking technology by combining plate information with signals transmitted by nearby electronic devices.

Even if you never gave permission for anyone to access your phone, smartwatch, Bluetooth devices, or your vehicle’s Wi-Fi system.

SignalTrace is essentially an add-on sensor that can be attached to existing license plate cameras. Instead of simply reading a plate, it searches for wireless signals coming from nearby devices: Bluetooth, Wi-Fi, RFID, and other identifiers.

Drive past one of these systems and it may detect the electronic signatures coming from your phone, smartwatch, Bluetooth headphones, infotainment system, AirTags, tire-pressure sensors, or other connected devices.

The system then links those electronic identifiers to a license plate. Leonardo calls this your “electronic fingerprint.”

In plain English, the goal is to connect vehicles with the electronic devices and people associated with them.

May the Fourth be with you

According to documentation referenced by multiple publications, SignalTrace isn’t limited to roadside cameras. The technology can also be deployed in parking garages, transportation hubs, event venues, and other public locations where wireless devices are present.

That means these systems can continue gathering information even when a vehicle isn’t the primary focus.

This raises two obvious questions.

First: Who controls the information about where you go and what devices you carry with you?

And second: How much of this surveillance is consistent with Americans’ expectations of privacy?

Privacy advocates argue that technologies like this raise serious Fourth Amendment concerns because they allow governments to collect detailed information about people’s movements and associations without individualized suspicion or a warrant.

Modern problems

That debate is only becoming more important as vehicles themselves become increasingly connected.

Modern cars already collect enormous amounts of information, including location data, driving behavior, route histories, voice commands, vehicle diagnostics, and in some cases information gathered through interior cameras and driver-monitoring systems.

Critics worry that systems like SignalTrace add yet another layer to an already expanding data ecosystem.

Most drivers don’t realize that they don’t fully control much of the information their vehicles generate. Manufacturers often determine who can access that data, whether it can be shared, and how long it is retained.

Now, layer SignalTrace on top of all that.

Not only can manufacturers collect information from connected vehicles, but external surveillance systems may now be able to detect the devices you bring into the car and tie those identifiers directly to your license plate.

Over time, that creates a remarkably detailed picture of your movements and routines.

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United Archives/Getty Images

Pattern of life

Privacy experts often refer to this as “pattern of life” surveillance. Collect enough data points, and it becomes possible to identify where someone works, where they live, who they regularly travel with, and even sensitive locations they frequently visit.

Leonardo says the technology captures identifiers and frequencies, not the contents of calls or messages. That may be technically true. But once detailed information exists inside a database, history shows that its use often expands over time.

So what does this mean for ordinary drivers?

It means the privacy expectations many Americans still have on public roads may be changing quickly.

It means the data ecosystem surrounding your vehicle is becoming larger and more interconnected.

And it means lawmakers need to have serious conversations about who can collect this information, how long it can be stored, and what can be done with it.

I’m not saying every police department will abuse these capabilities tomorrow. But once the technology exists and the infrastructure is already in place, the temptation to use it more broadly becomes very real.

We’ve seen that happen with other surveillance tools.

Protect yourself

So what can you do right now?

• First, familiarize yourself with your vehicle’s privacy and data settings. Many cars allow you to disable certain forms of data sharing or location tracking.
• Second, be mindful of Bluetooth and Wi-Fi. If you’re not using them, consider turning them off. These are precisely the types of signals systems like SignalTrace are designed to detect.
• Third, if you use AirTags, fitness trackers, or pet trackers, understand that those devices can also become part of your electronic footprint.
• Fourth, when you sell or trade your vehicle, factory-reset the infotainment system and remove all paired devices. Many people leave enormous amounts of personal information behind without realizing it.
• Finally, support serious data-privacy legislation and efforts to give consumers greater control over the information their vehicles generate.

Because technologies like this rarely arrive with a major announcement.

They appear quietly in police budgets, vendor contracts, and infrastructure projects.

And by the time most people notice, the system is already in place.

Bottom line: Your car is supposed to work for you, not the other way around. When surveillance systems start linking your license plate to the devices you carry every day, it’s worth paying attention — and asking some hard questions before these technologies become the new normal.

I’ll keep watching this space and bringing you updates as more departments adopt or test these systems. And I’ll let you know about the wins too.

If you’re wondering, “Where are all these cameras?” you will be shocked. Check out websites like deflock.org, an open-source project mapping license plate readers. Or look on eyesonflock.com, an aggregating Flock Safety Transparency Portal data, and haveibeenflocked.com, where you can enter your plate number to find out more.