Even under exigent circumstances, where law enforcement use of technologies that track cell-phone use are deemed immediately necessary, law enforcement must still get a pen register order. The pen register order is required by statute and policy even though exigency otherwise excuses police from having to obtain a conventional warrant. The Inspector General noted that the agencies didn't follow the rules in these cases either.
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.
Unfortunately, the report redacts crucial information regarding the total number of times that each agency used CSS with and without a warrant, and when they used the devices to support external information. The OIG should release this information to the public: knowing the aggregate totals would not harm any active investigation, but rather inform public debate over the agencies' reliance on this invasive technology. Make no mistake, cell-site simulators are mass surveillance that draws in the cell signal and collects data on every phone in the vicinity.
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. In 2022 we learned that HSI and ICE had used overly-broad warrants to collect bulk financial records concerning people sending money across international borders through companies like Western Union. Mass surveillance of this kind is a massive violation of privacy and has elicited the concern of at least one U.S. senator hoping to probe into these tactics.
Most people carry cell phones on them at any given moment. EFF will continue to fight against careless government use of cell-site simulators, and we will continue to monitor federal agencies that rely on secrecy and a strategic ignorance of the law in order to wield powerful and overly broad surveillance powers and technologies.