Case5:15-xr-90304-HRL Document30 Filed07/29/15 Page3 of 46 1 connection. Luna ¶ 3A. If a cell phone moves away from the cell tower with which it started a 2 call and closer to another cell tower, the phone connects seamlessly to that next tower. Blaze 3 Testimony at 50. United States District Court Northern District of California 4 Significantly, the government’s special agent from the Federal Bureau of Investigation 5 (“FBI”) informs the Court that CSLI may be generated in the absence of user interaction with the 6 cell phone. Luna Decl. ¶ 3B. For example, CSLI may still be generated during an incoming 7 phone call that is not answered. Id. Additionally, most modern smartphones have applications 8 that continually run in the background, sending and receiving data without a user having to 9 interact with the cell phone. Id. 10 Indeed, cell phones, when turned on and not in airplane mode, are always scanning their 11 network’s cellular environment. Luna Decl. ¶ 3B. In so doing, cell phones periodically identify 12 themselves to the closest cell tower—i.e., the one with the strongest radio signal—as they move 13 throughout their network’s coverage area. Blaze Testimony at 50. This process, known as 14 “registration” or “pinging,” facilitates the making and receiving of calls, the sending and receiving 15 of text messages, and the sending and receiving of cell phone data. See id. Pinging is automatic 16 and occurs whenever the phone is on, without the user’s input or control. U.S. Dep’t of Homeland 17 Sec., Lesson Plan: How Cell Phones Work 9 (2010) (“DHS Lesson Plan”), available at 18 https://www.eff.org/files/filenode/3259_how_cell_phones_work_lp.pdf. A cell phone that is 19 switched on will ping the nearest tower every seven to nine minutes. Id. At oral argument, the 20 Court was informed that at least some cellular service providers keep track of the CSLI generated 21 by registration “pings.” Hr’g Tr. at 4:19-5:6. 22 23 24 25 26 27 28 As the number of cell phones has increased, the number of cell towers—and thus cell sites—has increased accordingly: A sector can handle only a limited number of simultaneous call connections given the amount of radio spectrum “bandwidth” allocated to the wireless carrier. As the density of cellular users grows in a given area, the only way for a carrier to accommodate more customers is to divide the coverage area into smaller and smaller sectors, each served by its own base station and antenna. New services, such as 3G and LTE/4G Internet create additional pressure on the available 3 Case No. 15-XR-90304-HRL-1(LHK) ORDER AFFIRMING DENIAL OF APPLICATION FOR HISTORICAL CELL SITE LOCATION INFORMATION