The New Jersey Supreme Court has held, in State v. Thomas W. Earls, that the state constitution protects individuals’ right to privacy in their cell phones’ location data. New Jersey thus becomes the third state (after Montana and Maine) to prohibit state and local law enforcement from obtaining cell-site location data without a warrant. Following the U.S. Supreme Court’s ruling in U.S. v. Jones, in which the Court held that a warrant is required to track a car with a GPS device, law enforcement agencies have increasingly turned to cell-site data from mobile carriers as an alternative way to track suspects without a warrant. They have generally done so on the theory that cell users have no right to privacy in that data, as it is shared voluntarily with third parties ‒ their mobile carriers. As privacy concerns regarding the use of location data increases, states are pushing back against this trend. Several states are preparing legislation (like the laws in Montana and Maine) that would establish a warrant requirement, and others are following New Jersey’s lead by letting courts decide the warrantless tracking issue.