Federal Appeals Court Approves Warrantless Cellphone Tracking

On Tuesday a federal appeals court ruled that police do not need a warrant to obtain historical location data from cellphone companies because the Fourth Amendment does not protect such information. The U.S. Court of Appeals for the 5th Circuit concluded that the Supreme Court's "third party doctrine," which holds that people have no reasonable expectation of privacy in information they voluntarily disclose to others, applies to cellphone geolocation data, despite the wealth of personal details they can reveal. That means such records have only as much protection as Congress or state legislatures choose to provide. The 5th Circuit's decision comes less than two weeks after the New Jersey Supreme Court ruled, based on the privacy clause of that state's constitution, that police generally do need a warrant to obtain cellphone location data. This is the first time a federal appeals court has squarely addressed the issue.

http://reason.com/blog/2013/07/31/yes-that-is-a-spy-in-your-pocket-federal