December 2017 Preview | Carpenter v. United States

Case No. 16-402 | 9th Cir. Decision

Under longstanding Fourth Amendment principles, when a person willingly gives information to a third party, she loses an expectation of privacy in that information. Demands for such information therefore do not constitute “searches” within the meaning of the Fourth Amendment. Should the rule apply to smartphone data that can automatically transmit its owner’s location? In the most significant Fourth Amendment case on the Court’s docket this term, the Court will answer that question and potentially limit the breadth of the third-party doctrine.

The information at issue in Carpenter, called “cell site location information” (“CSLI”), records a cell phone’s location based on its connections to nearby cell towers to route calls and data. In urban areas, where cell towers are more densely packed, CSLI can pinpoint a phone’s location with greater precision. Moreover, as smartphone capabilities have multiplied, the volume of connections that they make has increased in turn.

Timothy Carpenter was convicted for his role in a series of armed robberies based in part on CSLI information obtained from his cell phone over a six-month period. Under the Stored Communications Act, 18 U.S.C. § 2703, the government applied for and obtained an order compelling Carpenter’s phone service provider to turn over the records based on “specific and reasonable facts to believe” the records were “relevant and material to an ongoing criminal investigation.” Carpenter moved to exclude the evidence on the grounds that the acquisition of the records constituted a search for which the government lacked probable cause. The district court denied the motion. The Sixth Circuit affirmed, invoking the third-party doctrine to conclude that acquisition of CSLI records did not constitute a search.

The Court has traditionally defined a search as a government action that invades a reasonable expectation of privacy. See Katz v. United States, 389 U.S. 347 (1967) (Harlan, J., concurring). The third-party doctrine emanates from that definition. In Smith v. Maryland, 442 U.S. 735 (1979), the Court held the use of a pen register to record the numbers a person dialed did not constitute a search because a person cannot reasonably expect to keep private numbers it voluntarily transmitted to a phone company. The government argues that Smith is controlling and prevents Carpenter from claiming a privacy interest in location data he transmits to his phone company.

Carpenter argues that CSLI is different from the data at issue in Smith. Given the great variety of tasks for which people have come to use smartphones, he argues, location data can provide the government a detailed and intrusive look into a person’s intimate affairs. Additionally, the Court recently recognized that smartphones pose unique Fourth Amendment concerns. In Riley v. California, 134 S. Ct. 2473 (2014), the Court required police to obtain a warrant before searching the contents of a smartphone due to the extensive volume of personal information the device contains.

Moreover, in United States v. Jones, 565 U.S. 400 (2012), the Court articulated a different test for a Fourth Amendment search based on unlawful trespass. There, the Court found the government had conducted a search when it attached a GPS device to a car and collected location coordinates over an extended period. Carpenter argues that the government’s use of CSLI is analogous to GPS tracking and therefore constitutes a search under the Fourth Amendment. The government replies that Carpenter failed to preserve this argument in the court of appeals, but argues that the case is distinguishable in any event because CSLI does not produce location data as precise as GPS coordinates.

Should the Court decide that the collection of CSLI constitutes a search, it will then have to decide whether such searches require a warrant. The Court could resolve that question on its own or remand to the Sixth Circuit. Still, those with interest in the Fourth Amendment–privacy advocates and law enforcement officials alike–will be interested to see how the Court resolves the threshold question.