Case5:15-xr-90304-HRL Document30 Filed07/29/15 Page24 of 46 1 tower. As the government’s FBI special agent explained, “CSLI for a cellular telephone may still 2 be generated in the absence of user interaction with a cellular telephone.” Luna Decl. ¶ 3B. “For 3 example,” the special agent continued, CSLI may be generated by “applications that continually 4 run in the background that send and receive data (e.g. email applications).” Id. At oral argument, 5 the government confirmed that its § 2703(d) application authorizes the government to obtain 6 historical CSLI generated by such activities. See Hr’g Tr. at 51:4-5. United States District Court Northern District of California 7 In addition, the government’s FBI special agent informed the Court that a cell phone “is 8 always scanning its network’s cellular environment.” Luna Decl. ¶ 3B. In so doing, a cell phone 9 periodically identifies itself to the closest cell tower—not necessarily the closest cell tower 10 geographically, but the one with the strongest radio signal—as it moves through its network’s 11 coverage area. Id.; Blaze Testimony at 50. This process, known as “registration” or “pinging,” 12 facilitates the making and receiving of calls, the sending and receiving of text messages, and the 13 sending and receiving of cell phone data. See id. Pinging nearby cell towers is automatic and 14 occurs whenever the phone is on, without the user’s input or control. DHS Lesson Plan at 9. This 15 sort of pinging happens every seven to nine minutes. Id. When “investigators desire to map the 16 physical movement of a subject” through historical CSLI, they may do so by obtaining “[a] record 17 of subject phone pings” from cellular service providers. Id. at 10. It is not clear that every cellular 18 service provider records CSLI generated by such pings, see id., but the Court was informed at oral 19 argument that Sprint, one of the cellular service providers listed in the government’s application, 20 does so, see Hr’g Tr. at 4:19-5:6. Although Sprint is not the service provider for any of the target 21 cell phones, the government concedes that the instant application allows the government to obtain 22 historical CSLI from Sprint if the target cell phones were to roam onto Sprint’s network5 or if one 23 of the targets were to switch from Verizon or AT&T to Sprint during the sixty-day period but keep 24 the same phone number pursuant to local number portability. See Schenk Decl. ¶ 1a; App. ¶ 2 & 25 26 27 28 5 Verizon and Sprint utilize “the same kind of system; so Sprint phones can connect to Verizon towers and vice versa.” Larsen Decl. ¶ 3a. 24 Case No. 15-XR-90304-HRL-1(LHK) ORDER AFFIRMING DENIAL OF APPLICATION FOR HISTORICAL CELL SITE LOCATION INFORMATION