Cell site location information today is so specific that collection and analysis requires a search warrant. It is as specific as GPS, and it can now pinpoint locations in a house. GPS was on a car; cell phones are on the person, so it tracks the person with a tower ping every six minutes, even if not calling. Moreover, Justice Sotomayor’s Jones concurrence about prolonged tracking was cited by the majority in Riley. A fascinating look at how CSLI works, too. In Re: Application for Telephone Information Needed for a Criminal Investigation Case, 2015 U.S. Dist. LEXIS 99871 (N.D.Cal. July 29, 2015):
… Densely populated urban areas therefore have more cell towers covering smaller geographic locations. For example, the Public Defender informs the Court that within three miles of the San Jose Federal Courthouse, there are 199 towers (with applications for three more currently pending) and 652 separate antennas. Opp. at 3. Within just one mile of the Federal Courthouse in New York City, there are 118 towers and 1,086 antennas. Id.
In addition to the large, three-sided cell towers, smaller and smaller base stations are becoming increasingly common. Examples include microcells, picocells, and femtocells, all of which cover a very specific area, such as one floor of a building, the waiting room of an office, or a single home. Blaze Testimony at 43-44. This proliferation of base stations to cover smaller areas means that “knowing the identity of the base station (or sector ID) that handled a call is tantamount to knowing a phone’s location to within a relatively small geographic area … sometimes effectively identifying individual floors and rooms within buildings.” Id. at 55-56.
Although the ability of cellular service providers to track a cell phone’s location within an area covered by a particular cell site might vary, it has become ever more possible for the government to use CSLI to calculate a cell phone user’s “locations with a precision that approaches that of GPS.” Id. at 53.
The government acknowledged as much at oral argument, conceding that CSLI has gotten more precise over the years. Hr’g Tr. at 32:5-9. The fact is new tools and techniques are continually being developed to track CSLI with greater precision. Cellular service providers, for instance, can triangulate the location of a cell phone within an area served by a particular cell site based on the strength, angle, and timing of that cell phone’s signal measured across multiple cell site locations. Blaze Testimony at 56.
Lastly, the volume of location data generated by an individuals’ cell phone can be immense, as the ACLU points out. See ACLU Br. at 5-7; ECF No. 19-1, Declaration of Nathan Freed Wessler (“Wessler Decl.”). For example, in United States v. Carpenter, a case now pending in the Sixth Circuit and arising out of the greater Detroit area, the government obtained 127 days of CSLI for one defendant, Timothy Carpenter, and 88 days of CSLI for another, Timothy Sanders. See United States v. Carpenter, No. 14-1572 (6th Cir. filed May 7, 2014). Carpenter’s data include 6,449 separate call records for which CSLI was logged, comprising 12,898 cell site location data points. See Wessler Decl. ¶ 8. Sanders’s records reveal 11,517 calls for which location information was logged, comprising 23,034 cell site location data points. Id. ¶ 9. Carpenter and Sanders, respectively, placed or received an average of 50.8 and 130.9 calls per day for which location data was recorded and later obtained by the government. Id. ¶ 10. For Carpenter, that amounts to an average of 102 location points per day, or one location point every 14 minutes. For Sanders, it amounts to an average of 262 location points per day, or one location point every six minutes.
Justice Sotomayor agreed with her four colleagues that prolonged electronic surveillance would violate the Fourth Amendment. Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring). She added, however, that “even short-term monitoring” raises concerns under Katz because “GPS monitoring generates a precise, comprehensive record of a person’s public movements that reflects a wealth of detail about her familial, political, professional, religious, and sexual associations.” Id.
Justice Sotomayor was particularly concerned with “the existence of a reasonable societal expectation of privacy in the sum of one’s public movements.” Id. at 956 (emphasis added). In particular, she wondered “whether people reasonably expect that their movements will be recorded and aggregated in a manner that enables the Government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on.” Id.; see also CIA v. Sims, 471 U.S. 159, 178 (1985) (finding it within the CIA director’s discretion not to disclose “superficially innocuous information” that might reveal an intelligence source’s identity because “what may seem trivial to the uninformed, may appear of great moment to one who has a broad view of the scene and may put the questioned item of information in its proper context” (brackets and internal quotation marks omitted)). When governmental actions intrude upon someone’s privacy to that degree, Justice Sotomayor concluded, a warrant is required. Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring).
Two years later, the U.S. Supreme Court cited Justice Sotomayor’s concurrence in Jones with approval in holding that police must obtain a warrant to search the contents of an arrestee’s cell phone. Riley v. California, 134 S. Ct. 2473, 2490 (2014). …
In fact, the information the government seeks here is arguably more invasive of an individual’s expectation of privacy than the GPS device attached to the defendant’s car in Jones. This is so for two reasons. First, as the government conceded at the hearing, over the course of sixty days an individual will invariably enter constitutionally protected areas, such as private residences. Hr’g Tr. at 18:15-24. Tracking a person’s movements inside the home matters for Fourth Amendment purposes because “private residences are places in which the individual normally expects privacy free of governmental intrusion not authorized by a warrant, and that expectation is plainly one that society is prepared to recognize as justifiable.” Karo, 468 U.S. at 714; see also Kyllo, 533 U.S. at 31 (“At the very core of the Fourth Amendment stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion.” (internal quotation marks omitted)). As one court put it, “Because cellular telephone users tend to keep their phone on their person or very close by, placing a particular cellular telephone within a home is essentially the corollary of locating the user within the home.” See In re Application of U.S. for an Order Authorizing Disclosure of Location Info. of a Specified Wireless Tel., 849 F. Supp. 2d 526, 541 (D. Md. 2011).
Second, the government conceded at oral argument that, compared to GPS tracking of a car, the government will “get more information, more data points, on the cell phone” via historical CSLI. Hr’g Tr. at 29:8-9; see also id. at 29:19-21 (“But, yes, of course the person has the phone more than they have their car, most people at least do, so it gives [the government] more data.”). Cell phones generate far more location data because, unlike the vehicle in Jones, cell phones typically accompany the user wherever she goes. See Wessler Decl. ¶¶ 8-10 (describing a Sixth Circuit case, United States v. Carpenter, where the government obtained 23,034 cell site location data points for one defendant over a period of eighty-eight days). Indeed, according to a survey cited by the U.S. Supreme Court in Riley, “nearly three-quarters of smart phone users report being within five feet of their phones most of the time, with 12% admitting that they even use their phones in the shower.” 134 S. Ct. at 2490 (citing Harris Interactive, 2013 Mobile Consumer Habits Study (June 2013)).
In finding a reasonable expectation of privacy in historical CSLI, the Court notes its agreement with another judge in this district. In United States v. Cooper, No. 13-CR-00693-SI-1, 2015 WL 881578, at *8 (N.D. Cal. Mar. 2, 2015), Judge Illston observed that “many, if not most, will find their cell phone quite literally attached to their hip throughout the day.” “All the while,” Judge Illston continued, “these phones connect to cell towers, and thereby transmit enormous amounts of data, detailing the phone-owner’s physical location any time he or she places or receives a call or text.” Id. “However, there is no indication to the user that making [a] call will also locate the [user].” Id. (internal quotation marks omitted) (quoting Third Circuit Opinion, 620 F.3d at 317). This Court agrees further with Judge Illston that an individual’s “reasonable expectation of privacy in his or her location is especially acute when the call is made from a constitutionally protected area, such as inside a home.” Id. Judge Illston’s reasoning is all the more compelling when one considers that historical CSLI is also generated by passive activities such as automatic pinging, continuously running applications (“apps”), and the receipt of calls and text messages. Moreover, over a sixty-day period, as the government concedes, the government would inevitably obtain CSLI generated from inside the home. Hr’g Tr. at 18:15-24.
What is more, society’s expectation of privacy in historical CSLI is evidenced by the myriad state statutes and cases suggesting that cell phone users “can claim a justifiable, a reasonable, or a legitimate expectation of privacy” in this kind of information. Knotts, 460 U.S. at 280 (internal quotation marks omitted). Although state law is not dispositive of the issue, “the recognition of a privacy right by numerous states may provide insight into broad societal expectations of privacy.” Cooper, 2015 WL 881578, at *8 (quoting United States v. Velasquez, No. CR 08-0730 WHA, 2010 WL 4286276, at *5 (N.D. Cal. Oct. 22, 2010)). In California, for instance, where this Court sits, it has been the law for more than three decades that police need a warrant to obtain telephone records. See People v. Blair, 25 Cal. 3d 640, 654-55 (1979); see also People v. Chapman, 36 Cal. 3d 98, 107 (1984) (“This court held [in Blair] that under the California Constitution, [telephone] records are protected from warrantless disclosure.”), disapproved of on other grounds by People v. Palmer, 24 Cal. 4th 856 (2001). As Blair involved nothing more than “a list of telephone calls” made from the defendant’s California hotel room, see Blair, 25 Cal. 3d at 653, there is little doubt that the California Supreme Court’s holding applies with full force to the government’s application here, which seeks historical CSLI generated by a target cell phone’s every call, text, or data connection, in addition to any telephone numbers dialed or texted.
Outside of California, the high courts of Florida, Massachusetts and New Jersey have all recognized a reasonable expectation of privacy in CSLI. See Tracey v. State, 152 So. 3d 504, 525-26 (Fla. 2014) (prospective CSLI); Commonwealth v. Augustine, 4 N.E.3d 846, 850 (Mass. 2014) (historical CSLI); State v. Earls, 70 A.3d 630, 644 (N.J. 2013) (prospective CSLI). The high courts of Massachusetts and New Jersey found a reasonable expectation of privacy under their respective state constitutions, while the Florida Supreme Court based its ruling on the federal Fourth Amendment. In reaching its decision, the Florida Supreme Court explained that “because cell phones are indispensable to so many people and are normally carried on one’s person, cell phone tracking can easily invade the right to privacy in one’s home or other private areas, a matter that the government cannot always anticipate and one which, when it occurs, is clearly a Fourth Amendment violation.” Tracey, 152 So. 3d at 524. Relying on Justice Sotomayor’s concurrence in Jones, the Florida Supreme Court found that “owners of cell phones or cars equipped with GPS capability do not contemplate that the devices will be used to enable covert surveillance of their movements.” Id. (citing Jones, 132 S. Ct. at 956 at n.* (Sotomayor, J., concurring)). On that basis, the Tracey Court held that the defendant “had a subjective expectation of privacy in the location signals transmitted solely to enable the private and personal use of his cell phone,” and that “such a subjective expectation of privacy of location as signaled by one’s cell phone—even on public roads—is an expectation of privacy that society is now prepared to recognize as objectively reasonable.” Id. at 525-26 (citing Katz, 389 U.S. at 360-61 (Harlan, J., concurring)).
Six more states have legislated privacy protections for historical CSLI. Colorado, Maine, Minnesota, Montana, Tennessee, and Utah have passed statutes expressly requiring law enforcement to apply for a search warrant to obtain this data. …
