An AP report details how law enforcement is using the Fog Reveal app to search hundreds of billions of records housed within 250 million mobile devices. They harness the data to merge with public records creating pinpoint locations, which weave a pattern known that investigators call pattern-of-life.

Fog Reveal differs from other location technologies used by police agencies. It follows and tracks phones and devices through specific advertising IDs which are numbers assigned to each device.

These numbers do not contain the name of the phone’s user but can be traced to homes and workplaces to help police establish pattern-of-life analyses.

Police agencies from suburban Southern California to rural North Carolina are using the cellphone tracking tool. It cost less than $10,000 for a one-year license. 

Cops can buy large amounts of location data on private citizens and track people's movements over at least 3 years back. And no search warrant is required.

The app's parent company, Fog Data Science LLC is a data broker headquartered in Leesburg, Virginia. And has offices in New Jersey, Ohio, and Texas.

The firm was founded in 2016 by Robert Liscouski, who headed up the Department of Homeland Security’s National Cyber Security Division in the George W. Bush administration. His co-founder Matthew Broderick, a former US Marine brigadier general, was also with DHS when he met Liscouski.

The company claims to collect 15 billion sets of data points daily from 250 million US devices every month, along with "tens of thousands" of mobile apps with intact tracking codes.

Fog Reveal vs privacy

Fog Reveal has been used in criminal investigations since at least 2018. And it has helped solve murders and has also been used to trace the movements of potential Jan. 6 participants who trespassed at the Capitol.

Prosecutors and police rarely, if ever, mention the tool in court records. And defense attorneys say the lack of transparency makes it harder for them to defend their clients in cases where the technology was used.

Defense attorneys are concerned that there are not currently enough legal restrictions on law enforcement’s use of all types of location data.

Fog Reveal is used under the radar by police agencies who don’t disclose in court that it's being used.

Michael Price, litigation director of the National Association of Criminal Defense Lawyers’ Fourth Amendment Center said “(Fog) is exceedingly rare to see in the wild because the cops often don’t get warrants. Even if you do ask for (information) sometimes they say, ‘We don’t know what you are talking about.’”

A person’s cell phone knows a lot. It is an extension of its owner. And that concerns privacy advocates.

“It’s sort of a mass surveillance program on a budget,” explained Bennett Cyphers, special adviser at the Electronic Frontier Foundation. The EFF is a digital privacy right advocacy group.

There is a pronounced lack of transparency surrounding Fog. Most law enforcement agencies refuse to discuss how they use the app.

Organizations like EFF believe its use violates the Fourth Amendment of the Constitution which protects against unreasonable search and seizure.