Opinion ID: 8704094
Heading Depth: 2
Heading Rank: 2

Heading: cell-site location records

Text: Cellular telephone companies maintain a system of towers to receive and transmit signals from cell phones. When a cell phone user places or receives a call, the cell phone sends a signal that is picked up by the nearest tower. In the regular course of business, cellular telephone companies generate and retain records of which cell tower a user’s phone was connected to at the beginning and end of each call. These records are only generated when the user places or receives a call; no such record is created when the phone is not in use. See In re Application of the United States of America for an Order for Disclosure of Telecommunications Records and Authorizing the Use of a Pen Register and Trap and Trace, 405 F.Supp.2d 435, 449 (S.D.N.Y.2005) (“Gorenstein Opinion”) (“[T]he data is provided only in the event the user happens to make or receive a telephone call.”). Because cell-site data does not identify a user’s precise location, but instead only identifies the cell phone tower nearest a user at the time of a call, the precision of cell-site data depends on the distance between cell towers in the user’s area. As one court has noted, “towers can be up to 10 or more miles apart in rural areas and may be up to a half-mile or more apart even in urban areas.” Id. 3 Some cell phone towers are further divided into three 120° sectors, such that the cell phone company can identify which of the three sectors the user was in when the call was placed. However, even that information is generally not precise enough to pinpoint a user’s location within a particular building. 4 Cell-site records may be obtained from the cell phone companies in two ways. The government may obtain this information after the fact, by requesting all such data accumulated over a specified time period. This is known as “historical” cell-site data. Alternatively, the government may seek to obtain this information on a real-time basis going forward from the date of the magistrate judge’s order. This is known as “prospective” cell-site data. The information is “identical regardless of whether it is obtained historically or prospectively.” (Opp’n at 2.) Each of the government’s applications in this case sought prospective cell-site data. In particular, the records obtained over the four-month period show for each call the defendant made or received: “(1) the date and time of the call; (2) the telephone numbers involved; (3) the cell tower to which the customer connected at the beginning and/or end of the call; and (4) the duration of the call.” (Id.)