U.S. Supreme Court Upholds Criminal Defendant’s Fourth Amendment Interest in Cell Site Data Held by Third Party

Kramer Levin Naftalis & Frankel LLP

In its June 22, 2018, decision in Carpenter v. United States, a 5-4 majority of the Supreme Court held that a criminal defendant’s Fourth Amendment rights were violated when the government obtained a court order requiring his wireless carriers to produce cell site location information (CSLI) for his cellular phone without a showing of probable cause. In his opinion for the majority, Chief Justice Roberts cautioned that the ruling was a narrow one that left existing precedent undisturbed and would not require a warrant for records held by a third-party in most cases. Nonetheless, the ruling marks a departure from the long-standing third-party doctrine and may signal new opportunities for criminal defendants to challenge a third-party's disclosure to the government of sensitive information concerning the defendant. 

Facts of the Case

In 2011, police arrested four suspects in a series of robberies at retail stores in Michigan and Ohio. One of the suspects confessed to the crimes and supplied police with the names and phone numbers of his accomplices. Based on this information, prosecutors applied for a court order under subsection 18 U.S.C. § 2703(d) of the Stored Communications Act (SCA), which provides that a court may compel disclosure of telecommunications records if the government submits “specific and articulable facts showing that there are reasonable grounds to believe” that the records “are relevant and material to an ongoing criminal investigation.” A magistrate judge in the Eastern District of Michigan granted the application and issued orders requiring the wireless carriers to produce historical CSLI for the suspects, one of whom was Timothy Carpenter. Carpenter’s wireless providers complied and furnished the government with 12,898 location points for Carpenter’s phone over a period of 127 days.

CSLI is a type of business record created by a wireless carrier whenever a cell-phone communicates with a cell phone tower or “cell site.” CSLI logs the time of a phone’s interaction with a cell site and the location of the cell site with which the phone communicated, generating a record of a phone’s location somewhere within a wedge-shaped area between one eighth and four square miles adjacent to a cell site. Each cell site can service a limited amount of data flow, requiring wireless providers to increase cell site density in urban areas and allowing them to determine a phone’s location through CSLI with greater precision. Law enforcement requests for cell site data are not infrequent — one wireless carrier reported 75,302 requests for CSLI between July 2015 and June 2016 — and advances in technology are bringing the precision of CSLI data closer to that provided by GPS tracking.

Carpenter was charged with 12 felony counts relating to the robberies and moved to suppress the CSLI prior to his trial, arguing that the government’s seizure of the records without a showing of probable cause violated the Fourth Amendment. The district court denied Carpenter’s motion, and the CSLI was used by the prosecution at trial to show Carpenter’s cell phone in proximity to four of the robberies at the time they occurred. Carpenter was convicted on all counts, and the Sixth Circuit affirmed his conviction, finding that he had no reasonable expectation of privacy in the CSLI because he had voluntarily shared the information with third-parties, namely, his wireless providers. Carpenter petitioned for certiorari, and the Supreme Court granted his petition.

The Majority Opinion

In an opinion joined by Justices Breyer, Ginsburg, Kagan and Sotomayor, Chief Justice Roberts identified two threads within the Court’s Fourth Amendment jurisprudence that could control the outcome of the case. The 1967 case United States v. Katz established that law enforcement agents are generally required to obtain a warrant based on probable cause prior to intruding into a sphere within which an individual has a reasonable expectation of privacy, and Carpenter argued he had such an expectation in the CSLI. But the Justices needed to reconcile past decisions articulating the “third-party doctrine,” under which individuals generally do not enjoy a protected Fourth Amendment interest in information that they voluntarily share with a third-party. The Court considered whether application of the third-party doctrine required a finding that Carpenter had no constitutionally protected privacy interest in the CSLI held by his wireless carrier, even though that data could be used to assemble a detailed history of his movements over an extended period.

In reaching its holding, the majority relied on a recent case involving similar issues. In United States v. Jones, decided in 2012, the Court held that the government was required to obtain a warrant prior to placing a GPS tracking device on a suspect’s vehicle. Chief Justice Roberts reasoned that “[m]uch like GPS tracking of a vehicle, cell phone location information is detailed, encyclopedic, and effortlessly compiled ... [it] provides an intimate window into a person’s life, revealing not only his particular movements, but through them his familial, political, professional, religious, and sexual associations” (internal quotations omitted). In fact, the Court concluded that CSLI obtained from a wireless provider is even more invasive than location information obtained via a tracking device because “when the Government tracks the location of a cell phone it achieves near perfect surveillance,” due to the fact that individuals “compulsively carry cell phones with them all the time.” Moreover, CSLI allows the government to reconstruct an individual’s past movements, rather than simply monitor present ones.

Because of the “unique nature of cell phone location records,” the Court decided that Carpenter did have a reasonable expectation of privacy in his CSLI that the third-party doctrine could not overcome. Chief Justice Roberts qualified his opinion by recognizing that the third-party doctrine would continue to control where the records held by the third-party revealed relatively little about the individual claiming Fourth Amendment protection, leaving intact precedent from cases applying the third-party doctrine to bank records or the numbers dialed on a landline phone. 

Four Dissents

Justice Kennedy, joined by Justices Thomas and Alito, advocated for a relatively strict application of the third-party doctrine, which he saw as grounded in the Fourth Amendment’s historical foundation in property law. Justice Kennedy wrote that customers “do not own, possess, control, or use the records, and for that reason have no reasonable expectation that they cannot be disclosed pursuant to lawful compulsory process.” He faulted the majority for relying on Jones, observing that the majority opinion in that case was based on the government’s trespass onto private property and not on an analysis of the defendant’s reasonable expectation of privacy in his movements. Justice Kennedy would not foreclose potential Fourth Amendment claims in situations where the government obtains the “modern day equivalents of an individual’s ‘papers’ or ‘effects’” from a third-party, but preferred the bright line of the third-party doctrine to the majority’s balancing inquiry. 

Writing separately, Justice Thomas indicated that he would dispense with the “reasonable expectation of privacy” formulation entirely and limit Fourth Amendment challenges to those from an individual based on an intrusion into “their [own] persons, houses, papers, or effects,” following the language of the amendment.

In an opinion joined by Justice Thomas, Justice Alito followed the other dissenting Justices in criticizing the majority for allowing Carpenter to object to a third-party’s disclosure of documents in which he had no property interest, but he also focused on the distinction between a search executed by law enforcement and a subpoena for documents. By imposing the standard for actual searches and seizures on a subpoena for documents, Justice Alito wrote, the majority upended centuries of precedent and set the bar too high for the government in obtaining subpoenas duces tecum

Finally, Justice Gorsuch’s dissent was critical of both the third-party doctrine, which he regarded as insufficiently protective of Fourth Amendment rights in the modern era, and the Katz “reasonable expectation of privacy” framework, which he found to be vague and unworkable. Justice Gorsuch would also prefer a return to the pre-Katz understanding of the Fourth Amendment as being grounded in property rights, but would take a flexible approach and look to legislatures for guidance in identifying property interests in records held by third-parties.


Though narrow in some respects, the Court’s opinion in Carpenter may provide support to defendants seeking to challenge the disclosure to the government of revealing records held by a third-party. With an expanding variety of devices and applications tracking our activities, it may be increasingly difficult to sustain the premise that individuals are voluntarily disclosing wide-ranging and intimate personal information to myriad service providers, and therefore have no privacy interests in that information. More broadly, Carpenter is just the latest in a series of recent decisions in which the Supreme Court has taken a flexible approach to adjudicating privacy rights in the digital age. Defendants may be able to use Carpenter and other recent Fourth Amendment case law to challenge the government’s investigative methods in an increasing array of situations.

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DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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