There are devices that are called “Stingrays” or “cell site stimulators,” which mimic cell phone towers. They are often installed in the back of a police car. Smaller versions can be held by hand and more powerful versions can be installed on aircrafts.
Police drive or walk around with them, sending out a signal that says, “Hey I’m a Sprint tower, or I’m a T-Mobile tower,” which forces every phone in the area to report back. The goal is to suck in a list of all the phones in the surrounding area—often in an attempt to find one particular suspect’s phone, and then hone in on exactly where it is located.
This technology raises serious privacy concerns, partly because of the dragnet effect — it affects lots of bystanders — and partly because it locates people not just on public streets, but inside homes or offices, which are constitutionally protected spaces.
Nathan Wessler, a lawyer with the ACLU’s Speech, Privacy, and Technology Project, monitors a government that increasingly monitors its citizens.
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