From Slate - http://www.slate.com/...
According to the Department of Justice, cellphone users can be tracked without a warrant because “no reasonable expectation of privacy” applies to location data. But lawmakers in Texas disagree—and are proposing strict new tracking regulations that could place the state at the forefront of nationwide efforts to rein in government surveillance.
Two identical bills filed at the end of last month in the state House and Senate propose a series of amendments to the Texas code of criminal procedure. The bills, submitted by Rep. Bryan Hughes, R-Mineola, and Sen. Juan Hinojosa, D-McAllen, would in all but exceptional cases require law enforcement agencies to get a search warrant to obtain cellphone location information—whether the phone is being tracked in real-time or retrospectively.
May be the DOJ and the rest of the nation should take the lead from Texas.