The U.S. Department of Homeland Security Is Buying Cellphone Geolocation Data to Track People

Hamed Aleaziz and Caroline Haskins, Buzzfeed News:

In an internal memo obtained by BuzzFeed News, the DHS’s top attorney, Chad Mizelle, outlined how ICE officials can look up locations and track cellphone data activity to make decisions on enforcement.


The document says that ICE and CBP purchased people’s mobile data from a data broker, although the document does not identify which one. All of the data is stored in an indexed, searchable database accessible through a “web portal.”

ICE and CBP buy advertising identifier data, or “AdID,” which typically includes information about where a person is located, what device they’re using, what language they use, which websites they’re visiting, and which websites they buy things from. All of this information isn’t linked to a person’s name, but to a randomly generated string of characters.


The document states that the DHS purchased AdID data that is anonymized and only shows “timestamped signal location(s) within a specific time period” — or where one device has been, and when. This in and of itself doesn’t tell ICE and CBP who a person is. But the document notes that it’s possible to “combine” the data “with other information and analysis to identify an individual user.”

The idea that bulk data collection can be anonymized is a lie, as is the notion that it is complex to de-anonymize it. This has long been known in industries able to exploit it, to everyone’s detriment. Now, it is powering a vast public-private partnership of surveillance by an organization that claims jurisdiction over a generous amount of U.S. territory with increasingly invasive capabilities and little accountability.