A growing controversy is unfolding after reports revealed that U.S. Customs and Border Protection has been purchasing location data collected through mobile apps and online advertising networks. An investigation by 404 Media cited an internal Department of Homeland Security document confirming the practice.

The data, gathered from various phone applications including popular games, is allegedly funneled through advertising agencies before being accessed by U.S. Customs and Border Protection. The information can be paired with analytical tools to track a device’s movements with striking precision.

By leveraging this system, authorities may identify sensitive locations such as a person’s home or workplace. Privacy advocates warn that such tracking raises constitutional and civil liberties concerns.

The method used to obtain much of the data is known as real-time bidding (RTB), an automated digital advertising process widely criticized by the Electronic Frontier Foundation. During RTB auctions, companies compete instantly for ad space while exchanging user data.

Experts argue that what was designed for targeted advertising has evolved into a powerful surveillance mechanism with limited public oversight. Calls for tighter regulation and greater transparency are intensifying nationwide.