Law enforcement agencies have been using an obscure cellphone tracking tool

Local law enforcement agencies from suburban Southern California to rural North Carolina have been using an obscure cellphone tracking tech tool, Mass Surveillance on a Budget, a new tech tool that allows them to follow people's movements months back in time. Former police data analyst Davin Hall quit the city's police force in part over its use of Fog Reveal, a powerful cellphone-tracking tool that the company says uses data from apps like Waze to track mobile devices. All mobile devices are assigned what's called an advertising identification number, a unique code that allows apps with location services to target consumers with promotions.

Mass Surveillance on a Budget:

Police have used "Fog Reveal" to search hundreds of billions of records from 250 million mobile devices, and harnessed the data to create location analyses known among law enforcement as patterns of life. The company said it does not access or have anything to do with personally identifiable information and is leveraging commercially available data. Fog heavily markets its product to law enforcement by promoting what it calls a 'pattern of life' analysis, which can stretch back months. Fog's tech tool is accessed through a web portal.

Local law enforcement is at the front lines of trafficking and missing person cases, yet these departments are often behind in technology adoption. Fog Reveal uses an identification number to track a device's wanderings when location services are enabled. Federal oversight of companies like Fog is an evolving legal landscape. There is the secrecy surrounding Fog, and details about its use, and most law enforcement agencies won't discuss it, raising concerns among privacy advocates that it violates the Fourth Amendment to the US Constitution, which protects against unreasonable search and seizure.