The Department of Homeland Security’s inspector general is investigating whether DHS’ purchase and use of cell phone location data to tracking Americans without a warrant is legal.

According to the Wall Street Journal:

…several agencies within DHS were buying access to a product made by a commercial broker, a company called Venntel Inc., of Herndon, Va., that contained location information on millions of U.S. mobile devices, drawn from games, weather apps and other common mobile applications. The department also buys software from Babel Street, another vendor that sells location-data products, according to public records. Venntel and Babel Street didn’t immediately respond to requests for comment.

Such data is widely used by the U.S. military and intelligence agencies for intelligence gathering overseas, according to public records and people familiar with the matter, but those agencies are largely barred from domestic monitoring. However, law-enforcement agencies have concluded that they don’t need a warrant to obtain location data on phones within the U.S. because consumers technically can opt out of such location tracking and the data is available for purchase on the open market.

The planned investigation by the DHS inspector general would be the latest probe into the implications of the government’s use of location data derived from mobile phones and whether it complies with the U.S. Constitution as well as a 2018 Supreme Court ruling that requires a warrant for some kinds of mobile-phone monitoring.

A big question is whether the DHS is trying to get around warrants – and a Supreme Court ruling – through an untested legal theory:

In Carpenter, the court said that geographic location data drawn from cellphones in the U.S. is a specially protected class of information because it reveals so much about Americans’ personal lives. The court put limits on law enforcement’s ability to obtain such data directly from cellphone carriers without warrants approved by judges.

The data DHS is using doesn’t come from the mobile carriers, however, but from marketing companies that collect it through software applications. As a result, DHS lawyers have concluded that Carpenter doesn’t apply—a legal theory untested in any court.

The Journal also reports the inspector general for the IRS is investigating that agency for its use of cellphone location data.

Image Credit: By Cellofellow (Gadsden_flag.svg) [CC0], via Wikimedia Commons