A device used by Baltimore police to track suspects is opening a new front in the national cell phone tracking and data privacy debate.

The devices in question are generically called “cell site simulators,” or “ISMI catchers,” and are made by the Harris Corporation. Known by the trade name “Stingray,” the devices mimic cell phone towers. When the device is flipped on, all phones in the area connect to the device, allowing police to see the precise location of the phone, its electronic serial number and other information.

Police can then track the subject they’re looking for.

At the same time, they also collect data from other people who just happen to be in the same area, and have no connection to the alleged crimes.

Issues surrounding the Stingray are complicated by the fact that the government won't talk about it.

The technology was exposed in a Baltimore case in which police planted a phone on a man they were tracking in a murder-for-hire case named Derrick Smith. According to the American Civil Liberties Union, police traced the phone to another man, Robert Harrison. When Smith was arrested, Harrison was named an accomplice because he had the phone.

As part of a national campaign to shine a light on Stingrays, the ACLU has taken up the case. In a brief filed in federal court, the organization argues that using a Stingray violates the 4th Amendment because police did not obtain a warrant to conduct an operation that essentially amounted to entering Harrison’s home through digital means. Police did apply for a court order to use the technology, but the ACLU argues it was for a pen register device, which only tracks the phone numbers called by a phone it is connected to. Further, the ACLU argues, police didn’t ask to obtain cell phone data from all of the people in the area.

Much like the ongoing national debate about data privacy, the issues surrounding the Stingray are complicated by the fact that the government won’t talk about it. In Harrison’s case, federal prosecutors argued that they had a “law enforcement privilege” that meant they did not have to discuss police tactics.


Authorities would even apparently rather lose in court than talk about the cell phone tracking. In a separate recent case, The Baltimore Sun reports that prosecutors withdrew important evidence that would have helped them win a robbery case because it would have required them to talk about the technology. When a judge asked police detective John L. Haley why he couldn’t talk about it, Haley cited a nondisclosure agreement with the FBI.

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