The technology tool offers the police “mass surveillance on a limited budget”

The technology tool offers the police “mass surveillance on a limited budget”

The technology tool offers the police “mass surveillance on a limited budget”

Local law enforcement from southern California suburbs to rural North Carolina have used an obscure cell phone-tracking tool, sometimes without a search warrant, which gives them the power to track people’s movements months back in time, according to public records and internal emails obtained from The Associated Press.

Police used “Fog Reveal” to search hundreds of billions of records from 250 million mobile devices and leveraged the data to create location analysis known among law enforcement as “life patterns,” according to thousands of pages of. company documents.

Sold by Virginia-based Fog Data Science LLC, Fog Reveal has been used since at least 2018 in criminal investigations ranging from the murder of a nurse in Arkansas to tracking the movements of a potential participant in the January 6 uprising at the Capitol. The tool is rarely, if ever, mentioned in court documents, which according to defense attorneys makes it more difficult for them to adequately defend their clients in cases where the technology has been used.

The company was developed by two former senior officials of the Department of Homeland Security under former President George W. Bush. It is based on advertising identification numbers, which Fog officials say have been pulled from popular mobile apps like Waze, Starbucks, and hundreds of others that target ads based on a person’s movements and interests, according to emails. of the police. This information is then sold to companies such as Fog.

“It’s kind of a mass surveillance program with a limited budget,” said Bennett Cyphers, a special advisor to the Electronic Frontier Foundation, a digital privacy rights advocacy group.


This story, supported by the Pulitzer Center for Crisis Reporting, is part of an ongoing Associated Press series, “Tracked,” which investigates the power and consequences of algorithm-driven decisions on people’s daily lives.


The documents and emails were obtained from EFF via Freedom of Information Act requests. The group shared the files with The AP, who independently discovered that Fog sold its software in approximately 40 contracts to nearly two dozen agencies, according to GovSpend, a company that monitors government spending. AP’s logs and reports provide the first public account of the extensive use of Fog Reveal by local police, according to analysts and legal experts who review those technologies.

“Local law enforcement is at the forefront of trafficking and missing persons cases, but these departments often lag behind in adopting the technology,” Matthew Broderick, a managing partner of Fog, said in an email. “We fill a gap for underfunded and understaffed departments.”

Due to the secrecy surrounding Fog, however, there are scant details of its use and most law enforcement will not discuss it, raising concerns among privacy advocates that it violates the Fourth Amendment to the United States Constitution. which protects against unreasonable searches and seizures.

What sets Fog Reveal apart from other cell phone tracking technologies used by the police is that it tracks devices through their advertising IDs, unique numbers assigned to each device. These numbers do not contain the phone user’s name, but can be traced to homes and workplaces to help police establish life pattern analysis.

“The ability he had to raise anyone in an area, whether in public or at home, seemed like a clear violation of the Fourth Amendment,” said Davin Hall, a former crime analytics supervisor for Greensboro, Department. Carolina Police Department. “I just feel angry and betrayed and I lied.”

Hall resigned in late 2020 after months of voicing concerns about the department’s use of fog to police lawyers and the city council.

While Greensboro officials acknowledged Fog’s use and initially defended it, the police department said it allowed the subscription to expire earlier this year because it did not “independently benefit the investigation. “.

But federal, state, and local law enforcement agencies in the United States continue to use Fog with very little public accountability. Local law enforcement agencies have been enticed by Fog’s affordable price – it can start at $ 7,500 per year. And some departments that license it have shared access with other nearby law enforcement, emails show.

Police departments also appreciate how quickly they can access detailed location information from Fog. Geofence warrants, which draw on GPS and other sources to track a device, can be accessed by obtaining such data from companies, such as Google or Apple. This requires the police to get a warrant and ask tech companies for the specific data they want, which can take days or weeks.

Using Fog’s data, which the company says is anonymous, police can geo-fence an area or search based on a specific device’s ad ID numbers, based on a user agreement obtained from AP. But Fog argues that “we have no way to reconnect the signals to a specific device or owner,” according to a sales rep who emailed California Highway Patrol in 2018 after a lieutenant asked if the tool could be used legally.

Despite those privacy guarantees, logs show that law enforcement can use Fog’s data as a clue to find identifying information. “There is no (personal information) attached to (listing ID),” wrote a Missouri official in Fog in 2019. “But if we’re good at what we do, we should be able to understand the owner.”

Federal oversight of companies like Fog is an evolving legal landscape. On Monday, the Federal Trade Commission sued a data broker called Kochava who, like Fog, provides its clients with advertising IDs that authorities say can easily be used to find where a mobile device user lives, which violates the rules. applied by the commission. And now there are bills before Congress that, if passed, would regulate the industry.

Broderick of Fog said in an email that the company does not have access to people’s personal information and draws from “commercially available data with no usage restrictions”, from data brokers “who legitimately purchase data from apps in accordance with their legal agreements “. The company refused to share information on how many law enforcement agencies it cooperates.

“We are confident that law enforcement has the responsible leadership, constraints and political guidance at the municipal, state and federal levels to ensure that any law enforcement tools and methods are used appropriately in accordance with the laws in the respective jurisdictions, ”Broderick said.


AP national writer Allen G. Breed contributed from Greensboro, North Carolina. Dearen reported from New York and Burke reported from San Francisco.


This report was produced in collaboration with researchers Janine Graham, Nicole Waddick, and Jane Yang, as well as the University of California, the Berkeley Center for Human Rights Investigation Laboratory, and the School of Law.


Follow Garance Burke and Jason Dearen on Twitter at @garanceburke And @jhdearen. Contact the AP Global Investigation Team at or

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