The Pentagon may be using commercial data to track Americans without due process, according to a letter from Sen. Ron Wyden, D-N.C., that was shared with Vice News. Wyden had asked the Department of Defense (DoD) about mobile location and other data it had purchased from commercial sources, following reports in the WSJ and elsewhere. The DoD responded to some questions, but many responses were not published. “I am writing to urge you to share information with the public about the Department of Defense’s unjustified surveillance of Americans,” Wyden replied.

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Various US law enforcement agencies have been purchasing various data from apps installed on Americans' phones to track alleged terrorists, illegal immigrants and other groups since at least 2017.
It is illegal for government agencies to directly monitor Americans under the U.S. Fourth Amendment without a warrant. Furthermore, the U.S. Supreme Court held in 2018 that it was also illegal to access cell phone location data without a court order (Carpenter). According to Wyden, however, the DoD’s spy agency, the Defense Intelligence Agency (DIA), has taken the position that these rules do not apply to commercial data “that the government purchases.”
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To that end, Wyden wanted to know if the DoD as a whole had subscribed to this “legal theory.” He also asked which other DoD agencies “buy and use data obtained on Americans, without a court order.”
The DoD responded to Wyden that it is up to each company to ensure it follows the law. The other responses were not shared, but Wyden believes they should be made public.
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Under the Trump administration, the US expanded the Patriot Act to allow for surveillance without checks (despite the Edward Snowden revelations) and it was recently upheld by the courts under Biden. However, it is still a gray area of the law as to where data purchases would fall under those rules. Now, Wyden and others are proposing new legislation called “The Fourth Amendment Is Not For Sale Act” that would force law enforcement to obtain warrants for location and other data purchased from law enforcement agencies.
Information source: engadget.com
