Your phone can tell a lot about you: where you've been, where your home and workplace are, and where your favorite places are. Federal agents are taking advantage of location data siphoned from advertisers through seemingly innocuous apps that you download for weather updates or cheap gas prices, and now a government watchdog is investigating the surveillance program.
In a letter dated Nov. 25, the Department of Homeland Security's inspector general, Joseph Cuffari, said his office would audit US Customs and Border Protection's use of commercial databases to track people by way of their phone locations. CBP is a branch of Homeland Security.
In a landmark case, the Supreme Court ruled in 2018 that law enforcement agents much get a warrant to track people via their phone location, but agencies have been circumventing the requirement by simply buying the data from businesses that maintain commercial databases.
"The objective of our audit is to determine if the Department of Homeland Security (DHS) and its components have developed, updated, and adhered to policies related to cell-phone surveillance devices," Cuffari said in the letter.
Apps request your permission for them to collect location data from your device so they can offer desired services -- such as when a weather app needs to know where you are so it can tell you if it's going to rain in your area.
But once the apps collect the data, they can also pass it on to data brokers, who provide it to advertisers for targeted commercials. Unless you're resetting your app permissions or your device advertising ID every day, the tracking can provide a long history of your whereabouts.
The Wall Street Journal, which first reported the DHS' internal investigation on Wednesday, revealed in February that CBP was using phone location data for immigration enforcement. The data came from a company called Venntel, which collected information on millions of devices by way of gaming and weather apps.
In November, Motherboard also reported that the US military bought location data collected from apps like Muslim Pro, which requires location data because it tells users which direction to face in order to pray toward Mecca.
The DHS' investigation comes after requests from a group of Senate Democrats in October, noting that the agency spent half a million dollars to access location data from Venntel.
"CBP is not above the law and refused to answer questions about purchasing people's mobile location history without a warrant -- including from shady data brokers like Venntel," Sen. Elizabeth Warren, a Democrat from Massachusetts, said in a statement. "I'm glad that the Inspector General agreed to our request to investigate this potentially unconstitutional abuse of power by the CBP because we must protect the public's Fourth amendment rights to be free from warrantless searches."
Agencies like the Internal Revenue Service have also used Venntel to track people. The IRS is also opening its own investigation into how it uses people's location data without a warrant.
Venntel didn't respond to a request for comment.
Also on Wednesday, the American Civil Liberties Union announced it is suing the DHS to turn over all records related to the agency's purchase and use of phone location data.
"If federal agencies are tracking American citizens without warrants, the public deserves answers and accountability," Sen. Ron Wyden, a Democrat from Oregon, said. "I won't accept anything less than a thorough and swift inspector general investigation that sheds light on CBP's phone location data surveillance program."