Tomorrow, the Department of Justice will tell a federal appeals court panel in New Orleans that law enforcement agents should be permitted to obtain two month's worth of historical cell phone location information without a warrant. Several civil liberties groups, including the ACLU, have filed briefs arguing otherwise (you can read our amicus brief here). We believe that cell phone location data, particularly when collected over a lengthy period of time, reveals intimate facts about a person's private life. The appropriate legal standard for such private information should be a probable cause warrant, issued by a judge.
In October 2010, federal prosecutors in Texas submitted three applications for court orders requiring the disclosure of 60 days of cell-tower location data in three separate investigations. Soon after, Magistrate Judge Stephen Smith issued an opinion denying the government's location-tracking applications, declaring that "compelled warrantless disclosure of cell site data violates the Fourth Amendment."