"People buy cell phones to communicate with others, to use the internet, and for a growing number of other reasons," Rabner wrote, "But no one buys a cell phone to share detailed information about their whereabouts with the police"

http://www.nj.com/politics/index.ssf/2013/07/police_need_warrants_to_track_cell-phone_data_nj_supreme_court_rules.html