Jeffrey Bishop
Information Privacy Law
Professor Ira Rubinstein
March 30, 2017

Ninth Circuit to Address Police Surveillance of Cell Site Location Information
Do consumers possess a Fourth Amendment “reasonable expectation of privacy” in the location data collected by cell phone service providers, such that police must obtain a warrant supported by probable cause to access this information? This was the chief question before the US Court of Appeals for the Ninth Circuit on March 17 during oral argument in United States v. Gilton. Although the four circuits that have considered the question have concluded (albeit in fractured opinions) that Fourth Amendment protections do not apply, at least two of the three judges on the Ninth Circuit panel indicated a willingness to find otherwise, raising the specter of a circuit split.
At issue is the historical cell site location information (CSLI) collected as a matter of routine business practice by cell phone service providers like Sprint. In order for a cell phone to function, it must periodically send a radio signal to a nearby cell site to connect to the service provider. Every time a call is made or received on a phone, a record is logged with the service provider based on the cell site information, including the location of a phone relative to the cell site at the beginning and end of a call. With the proliferation of smartphones, these radio signals are sent to cell sites with increasing frequency, as much as “every few minutes,” as phones now send radio signals when automatically checking for emails, streaming videos, and engaging in other forms of data usage. Though the accuracy of the CSLI is dependent on factors such as the density of cell towers in any given area (e.g. dense urban areas make location tracking more precise than a large, rural area with a single tower), by aggregating the CSLI data points over time, one is able to track the movements of a cell phone user throughout her day.
Under the facts of Gilton, investigators suspected Gilton of criminal activity and ordered Sprint, pursuant to a defective warrant, to deliver 37 days of Gilton’s cell phone records containing 8,790 CSLI data points – an average of “one [location point] every six minutes.” During oral argument and in their briefs, the US Government and the ACLU (as amicus in support of Gilton) sparred over whether the Government’s gathering of CSLI without a valid warrant (and, consequently, without probable cause) constituted a “search” that could fall within the protections of the Fourth Amendment.
Of particular interest to the parties and the questioning judges was the applicability of the “third-party doctrine” to modern, invasive technology. This doctrine derives from the decades old Supreme Court holdings in United States v. Miller (1976) and Smith v. Maryland (1979) where the Court held that there was no reasonable expectation of privacy in one’s banking transaction data and phone numbers dialed from a home landline phone because the defendants in each case had voluntarily conveyed that information to a third party – a bank teller or the phone company – and consequently “assumed the risk” of disclosure to state authorities. In such scenarios, government
investigators are permitted to obtain information without the ordinary requirements of a warrant and probable cause since, without a reasonable expectation of privacy, there has been no “search” subject to Fourth Amendment protections.
The Government relied heavily on these “third-party doctrine” precedents in arguing that Gilton’s historical CSLI was voluntarily conveyed to Sprint pursuant to the ordinary business agreement between a phone user and her service provider. Consequently, they argued, there can be no reasonable expectation of privacy in the CSLI, no Fourth Amendment “search,” and no requirement to obtain a valid warrant subject to a probable cause standard.
Judges Bybee and McKeown expressed their skepticism over the notion that consumers “voluntarily” hand over CSLI to their service providers since a consumer cannot possibly know to which cell site her phone is connecting. Judge McKeown further questioned the strength of the voluntariness theory where CSLI is collected even where a person chooses not to answer an incoming call. Counsel for the Government, however, found voluntariness inherent in the business relationship between a consumer and service provider, stating that “in order to get cellular phone service, you know that you have to connect your phone to the cellular network’s towers and you know that you have to be in range of those towers to get service…to make or receive phone calls.” The Government additionally contended that Sprint’s terms of service and privacy policies notify the user that Sprint “generally know[s] the location of your device.” Nonetheless, Judges Bybee and McKeown appeared concerned that the Government’s position left no limiting principle for warrantless searches in an age where technology is ubiquitous and often requires the sharing of sensitive, detailed information with service providers.
Echoing these concerns, counsel from the ACLU argued that the third-party doctrine is not a “categorical” rule, but that it only allows for an exception to the warrant requirement where the information is both “voluntarily conveyed” and the information is not particularly “private or sensitive.” Admitting that CSLI does not provide information on the “contents of the phone calls,” the ACLU contended that “this kind of pervasive, long-term location information is closely analogous to content information in the very detailed picture of a person’s life that it paints.” Their brief explains that police can infer from CSLI where one sleeps at night, her demographic information, and even the associational groups she frequents, potentially raising First Amendment concerns. Judge Wallace pressed the ACLU to distinguish CSLI from the numbers dialed from a phone in Smith which could also provide an “awful lot of information” yet is still not subject to the warrant requirement. The ACLU distinguished the cases in that phone numbers dialed are “voluntarily conveyed” to the phone company because they are “necessary to connect that call.” This contrasts with CSLI in which a user has no way to know what location information is being conveyed to the service provider, and the user does not necessarily take affirmative action to send over that information.
Moreover, the ACLU stressed that the fundamental question is “whether the warrant requirement is going to maintain vitality in the modern digital age.” Concerns over “dragnet” surveillance by police has led the Supreme Court to caution lower courts not to emphasize “pre-digital precedents” when applying them to newer, pervasive technologies. Modern cell phones should carry a stronger expectation of privacy since they are often carried wherever one goes, even into traditionally “constitutionally protected spaces” such as one’s home. Channeling the concerns of privacy
advocates, the ACLU argued that it can’t be that the third-party doctrine swallows the warrant requirement of the Fourth Amendment. In an age where a cell phone can be considered a “feature of the human anatomy,” the ACLU maintained that owning one is hardly a choice and “users should [not] be required to disable the core functionality of their phone in order to avoid…warrantless surveillance.”
The Ninth Circuit panel is expected to release an opinion in United States v. Gilton shortly. Other issues in Gilton – such as the applicability of the “good faith exception” in relying on a defective warrant and the Ninth Circuit’s requirement that a “compelling reason” must exist to create a circuit split – leave open the possibility that the Court may not reach the question of whether one can possess a reasonable expectation of privacy in CSLI. However, the Ninth Circuit is in the unique position of potentially being the first circuit court to find that CSLI is protected by the Fourth Amendment. Information privacy advocates should be following this case intently.
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