The Federal Government has used the mobile phone tracking 'Triggerfish' gadget for years now, and sometimes with great success. That's because its an effective, invasive piece of hardware: by posing as a cell tower Triggerfish is able to quickly glean valuable identifying data from phones. Like phone taps, this had previously been thought to have been used only with the telcos' approval, and after law enforcement officials had found "probable cause" to monitor someone. That supposed caveat was a minor comfort to privacy hounds, but as is so often the case with these things, might have been, shall we say, slightly optimistic.
In response to a Freedom of Information Act request by the American Civil Liberties Union and the Electronic Frontiers Foundation, the Justice Department has sent back evidence that law enforcement officials can use Triggerfish pretty much whenever they want, without consulting the phone companies. This looks like the use of was could most charitably be called a giant goddamn loophole: secret Triggerfish deployment is OK because it only provides its users with rough location data by pairing serial numbers, phone numbers and other identifiers to a particular tower, rather than the actual content of conversations. The moral problems here are multifaceted, but the practical ones for, you know, fugitives, are easily solved: turn off your phone. You're welcome! [Ars]