What’s the Standard for Location-Tracking?

The ACLU and EFF are filing a Freedom of Information Act request to find out how the government decides when to use triangulation from cell phones to determine someone’s location. Enchanced 911 rules require cell phone providers to pinpoint a phone’s location. The E911 rules were originally designed to aid emergency responders. But now, some reports suggest that federal police officers are using the location tracking information as part of routine investigations. The ACLU and EFF want to know whether the feds are getting the information using probable cause or some lesser standard. I doubt they’ll find any good news (if the government even complies with the FOIA request), but I’m still hoping.