Government couldn’t track location of cell phone without probable cause

In the case of In the Matter of the Application of the United States of America for an Order Authorizing the Disclosure of Prospective Cell Site Information, the U.S. District Court for the Eastern District of Wisconsin denied the government’s application for disclosure of “cell [s]ite information” pursuant to the Stored Communications Act (SCA), 18 U.S.C. § 2703, and the pen register statute, 42 U.S.C. § 3122.

The government sought cell site information so that it could track the general whereabouts of a criminal suspect. Cell site information is a record of the cell towers a cell phone connects to while the phone is turned on. The government, with cell cite information, can determine the location of a suspect possessing the cell phone. For more information on the technical aspects of cell site information, refer to this Wikipedia article.

The court noted at the outset that the issue in the case was not whether the government could obtain cell site information (it can), but rather what standard the government must meet to obtain such information. As a preface to the analysis of that issue, the court set out the three ways the government generally may access information related to telephone usage.

First, the government can listen in on calls if it shows probable cause and obtains a “super-warrant” under 18 U.S.C. §2518(3). Second, if it seeks records pertaining to a subscriber to an electronic communications service, it must show “specific and articulable facts” showing the records are relevant and material to the investigation. (See the Stored Communications Act at 18 U.S.C. §2703.) Third, the government can proceed under 18 U.S.C. §3122(b)(2) (the “pen register statute”) to obtain the numbers dialed from a phone or the numbers from which calls are made to a target phone.

The government claimed that by seeking cell site information, which included information about the towers used by the suspect’s phone and a map of tower locations, it was not requesting precise tracking information. Because it would only be able to determine the general neighborhood of the suspect, the government argued that the proper standard for obtaining the information should be “likely to be relevant” or “specific and articulable facts,” rather than the higher standard of “probable cause.”

The court rejected the government’s argument, citing to the Communications Assistance for Law Enforcement Act (“CALEA”). CALEA expressly prohibits the government from obtaining “information that may disclose the physical location of the subscriber” except where the probable cause standard has been met. Although the text of CALEA does not indicate how granular the term “physical location” is to be interpreted, the court held that the general geographical location revealed by cell site information clearly is a “physical location.” Accordingly, the “probable cause” standard was appropriate.

The government had not met its burden, so the request was denied.

In the Matter of the Application of the United States of American for an Order Authorizing the Disclosure of Prospective Cell Site Information, 2006 WL 2871743 (E.D. Wis., October 6, 2006).