Carpenter v. United States
585 U.S. ___ (2018) (2018)
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Rule of Law:
An individual maintains a legitimate expectation of privacy in the record of their physical movements as captured through cell-site location information (CSLI), so the government's acquisition of such records is a search and generally requires a warrant.
Facts:
- In 2011, police investigated a series of armed robberies at Radio Shack and T-Mobile stores in Michigan and Ohio.
- An arrested suspect confessed to the robberies, identified Timothy Carpenter as an accomplice, and provided Carpenter's cell phone number to the FBI.
- Carpenter's wireless carriers, MetroPCS and Sprint, routinely collected and stored historical CSLI for their business purposes.
- CSLI is generated automatically each time a phone connects to a cell site, creating a detailed, time-stamped record of the user's past movements.
- The government acquired 127 days of Carpenter's historical CSLI from his wireless carriers.
- This data consisted of 12,898 separate location points, which allowed the government to create a comprehensive chronicle of Carpenter's whereabouts.
Procedural Posture:
- The government obtained court orders under the Stored Communications Act directing Timothy Carpenter's wireless carriers to produce his historical cell-site records.
- Carpenter was charged with robbery and firearms offenses in the U.S. District Court for the Eastern District of Michigan.
- Before trial, Carpenter filed a motion to suppress the cell-site records, arguing their acquisition without a warrant violated the Fourth Amendment.
- The District Court denied the motion to suppress.
- Carpenter was convicted by a jury on multiple counts.
- Carpenter appealed to the U.S. Court of Appeals for the Sixth Circuit, where he was the appellant and the United States was the appellee.
- The Sixth Circuit affirmed the district court's decision, holding that Carpenter had no reasonable expectation of privacy in his cell-site records under the third-party doctrine.
- The U.S. Supreme Court granted Carpenter's petition for a writ of certiorari.
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Issue:
Does the government's acquisition of at least seven days of historical cell-site location information (CSLI) from a wireless carrier constitute a Fourth Amendment search?
Opinions:
Majority - Chief Justice Roberts
Yes, the government's acquisition of historical CSLI constitutes a Fourth Amendment search. An individual maintains a legitimate expectation of privacy in the whole of their physical movements. The pervasive, involuntary, and comprehensive nature of CSLI collection distinguishes it from the limited business records considered in Smith v. Maryland and United States v. Miller. Unlike bank records or dialed phone numbers, CSLI provides an intimate and detailed chronicle of a person's life, including their movements into private spaces. Because cell phones are an indispensable feature of modern life, a user does not voluntarily 'share' their location data in a way that defeats their privacy interest. Therefore, the third-party doctrine does not apply, and obtaining such records is a search that generally requires a warrant.
Dissenting - Justice Kennedy
No, the government’s acquisition of CSLI does not constitute a Fourth Amendment search. CSLI are business records created, owned, and controlled by the wireless carriers, not by the customer. Under the established third-party doctrine of Smith and Miller, individuals have no reasonable expectation of privacy in information they voluntarily convey to a third party. CSLI is no different from the financial and telephone records previously held to be outside the Fourth Amendment's protection. The Court's decision creates an unprincipled and unworkable distinction that will frustrate legitimate law enforcement investigations.
Dissenting - Justice Thomas
No, the acquisition of CSLI was not a search of Carpenter's property. The foundational problem is the Katz 'reasonable expectation of privacy' test itself, which has no basis in the text or history of the Fourth Amendment. The Amendment protects against searches of 'their persons, houses, papers, and effects.' The cell-site records belong to the wireless carriers, not to Carpenter, and therefore the government's action did not search anything that was his property. The Court should abandon the Katz test and return to a property-based Fourth Amendment analysis.
Dissenting - Justice Alito
No, the government action in this case was not a search. The Court's reasoning fractures two fundamental Fourth Amendment pillars: the distinction between an actual search and an order to produce documents (like a subpoena), and the rule that a defendant cannot object to a search of a third party's property. Historically and under modern precedent, a court order to produce records is, at most, a 'constructive search' that is governed by a less-demanding reasonableness standard, not the probable cause required for a warrant. By treating this court order as a full-blown search, the decision threatens to cripple legitimate investigative tools like grand jury subpoenas.
Dissenting - Justice Gorsuch
No, under the flawed precedents of Smith and Miller, the government's action was not a search. However, both Smith and Miller, and the underlying Katz test, are deeply problematic and out of step with modern realities. A better approach would be to return to traditional property law concepts, asking whether CSLI could be considered a user's 'papers' or 'effects.' Under principles of property, bailment, or positive law, a user might retain a protected interest in their data even when it is held by a third party. Unfortunately, Carpenter forfeited this more promising argument by relying solely on Katz.
Analysis:
This decision represents a landmark shift in Fourth Amendment jurisprudence, creating a significant exception to the long-standing third-party doctrine for the digital age. It establishes that individuals retain a reasonable expectation of privacy in the comprehensive record of their physical movements, even when that data is held by a third party like a wireless carrier. The ruling's narrow focus on historical CSLI leaves open critical questions about real-time tracking, 'tower dumps,' and other forms of digital data, setting the stage for future litigation to define the boundaries of digital privacy. The case signals the Court's willingness to adapt Fourth Amendment principles to the realities of modern technology's pervasive surveillance capabilities.
