In case you, like me, were wondering wtf stingrays are (besides a type of fish). This is from their report :

Cell-site simulators, also known as “Stingrays” or IMSI catchers, are devices that masquerade as legitimate cell-phone towers, tricking phones within a certain radius into connecting to the device rather than a tower.

Cell-site simulators operate by conducting a general search of all cell phones within the device’s radius, in violation of basic constitutional protections. Law enforcement use cell-site simulators to pinpoint the location of phones with greater accuracy than phone companies. Cell-site simulators can also log IMSI numbers (unique identifying numbers) of all of the mobile devices within a given area.

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The fact that government agencies are using these devices without the utmost consideration for the privacy and rights of individuals around them is alarming but not surprising. The federal government, and in particular agencies like HSI and ICE, have a dubious and troubling relationship with overbroad collection of private data on individuals.