The FBI has confirmed to the Senate it is once again buying data that can track US citizens' locations. This practice, which skirts the Fourth Amendment entirely, has become common among law enforcement agencies. While the Carpenter v. United States case prohibited warrantless access to carrier data, agencies have found a loophole by purchasing location information from data brokers.

When your phone connects to the internet, it broadcasts identifying information including your IP address, device type, and GPS coordinates. This data, known as Bidstream, fuels Real Time Bidding (RTB) systems that auction your attention to advertisers. Data brokers aggregate this information with other sources like personal details you provide to platforms, creating detailed profiles that can be licensed to various buyers.

In January, 404Media revealed ICE purchased tools from cybersecurity company Penlink, including Webloc, which can identify and track smartphones in specific areas. Other agencies using similar data include the Department of Homeland Security, Customs and Border Protection, the Secret Service, and the IRS. The Electronic Frontier Foundation is pushing for the Fourth Amendment is Not For Sale Act to close this loophole, but passage remains uncertain.