The Third Circuit Court of Appeals in Philadelphia is hearing oral arguments today regarding citizens’ privacy while using mobile phones. With federally mandated GPS locators built into the hardware of all new cellular phones, police have been tapping mobile phones to find the location of criminals for years, but the laws regarding such tactics are ambiguous and outdated.

The Obama administration has argued that Americans don’t enjoy a “reasonable expectation of privacy” when it comes to their whereabouts as revealed by their cell phones, and therefore warrant-less tapping is allowed. Not only that, but lawyers for the U.S. Department of Justice say that “a customer’s Fourth Amendment rights are not violated when the phone company reveals to the government its own records” showing where calls were placed or received.

According to CNET news, “Those claims have alarmed the ACLU and other civil liberties groups, which have opposed the Justice Department’s request and plan to tell the U.S. Third Circuit Court of Appeals in Philadelphia that Americans’ privacy deserves more protection and judicial oversight than what the administration has proposed.”

Kevin Bankston, an Electronic Frontier Foundation attorney who is arguing the case, paints it as “a critical question for privacy in the 21st century,” adding, “If the courts do side with the government, that means that everywhere we go, in the real world and online, will be an open book to the government unprotected by the Fourth Amendment.”