Court documents ordered released by a judge in Oakland, California, have revealed rare insights into how local police and the FBI use a sophisticated surveillance device known as Stingray.

Stingray, manufactured by the Delaware-based Harris Corporation, is one of a class of devices known as “cell site simulators” or “IMSI-catchers”. About the size of a suitcase, they work by pretending to be a cellphone tower in order to strip metadata and in some cases phone content and data from nearby devices tricked into connecting to it.

Despite the fact that the devices are also capable of listening to phone calls, in many cases they still do not require a warrant to use, instead requiring a much lower-level authorisation known as a “trap-and-trace”, a court order designed in the era of the rotary phone.

However, following several years of reporting by the Guardian, Ars Technica, the Wall Street Journal and others, some states – including California – and some federal agencies now require a full warrant for their use.

The Oakland documents, which were first reported on by Ars Technica, show that the city police department used its Stingray device for several hours in a search for a suspect named Purvis Ellis, the lead defendant of four alleged members of an Oakland gang facing trial on nine federal charges including the attempted murder of a police officer in January 2013.

Read more at The Guardian

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