Does the government need a warrant to acquire your cell phone's location data?

YOU MAY NOT realize it, but the cell phone in your pocket creates a time-stamped map of everywhere you go: where you shop, where you receive medical care, and how often you frequent a church, school, or gun range. That's because cell phones automatically connect to the nearest cell phone tower, and by doing so, constantly determine and record the user's location.

Today the Supreme Court will hear arguments in Carpenter v. United States, a major Fourth Amendment case that questions whether the police can access your phone’s location data without a warrant. The government argues that it should always be entitled to that information, no questions asked, because the 95 percent of American adults who own cell phones choose to give up that information “voluntarily.” Because cell phones transmit that data automatically, however, cell phone users have no choice in revealing their location. Therefore, the only action that could be “voluntary” is owning or using a cell phone.

The problem is that cell phones are no longer meaningfully voluntary in modern society. They have become central to society’s basic functions, such as employment, public safety, and government services. The cell phone is a revolutionary technology, but its real value comes not from its technical capabilities, but from its near-universal adoption.