Do Police Need a Warrant to See Where a Phone Is?

Right now, many Americans generate a detailed database of their whereabouts over time—as they move throughout the day from their workplace to their doctor, from their own house to their partner’s—that they do not see or control. It’s called “cell-site location information,” or CSLI, and it can be accessed by local, state, or federal law enforcement without a warrant. In other words, if the government wants to know your every location for the past year, they never need to prove they have probable cause to suspect you of a crime to a judge. Gathering this kind of location information, to be clear, is not some uncommon and esoteric procedure. Does this practice violate the Constitution? Right now, no. But recently its critics have scored some of their first major victories in court.