Memorandum: Legal Standard for Disclosure of Cell-Site Information (CSI) and Geolocation Information [June 29, 2010] [open pdf - 132KB]
"This memorandum was prepared to respond to your request for a legal overview of cases concerning government requests for geolocation information held by private companies to find a customer's location, and for a discussion of the scope and conflicting nature of those cases. Geolocation information 'can give the location of a cell phone within several hundred meters.' Cell-site information (CSI) generally 'provides the location of the cell phone tower supplying service to a cell phone when it is actually engaged in a call.' You have inquired as to what legal standard is necessary to obtain court ordered disclosure of cell-site information and geolocation information from cell phone service providers. Most of the cases discussed below involve government applications to obtain cell-site location information. As noted by scholars, advances in cellular phone technology 'are occurring so rapidly that they blur distinctions made by legislatures and courts as to what is required to investigate, track, and/or search and seize a cellular telephone.' Reform proponents contend that 'ECPA [Electronic Communications Privacy Act] is a patchwork of confusing standards that have been interpreted inconsistently by the courts, creating uncertainty for both service providers and law enforcement agencies.'"
Federation of American Scientists: http://www.fas.org/