Criminal Justice

Carpenter v. United States

In Carpenter v. United States, the Supreme Court is considering whether the Fourth Amendment permits police to obtain cell phone location records that show an individual’s location and movements over the course of 127 days without first obtaining a warrant.

Case Summary

In 2011, Detroit police obtained records from Timothy Carpenter’s cellular service provider showing the movements of his cell phone. From those records, they were able to track Carpenter’s whereabouts over a four-month period. Based in part on information obtained from those records, Carpenter was convicted of six different robberies. Carpenter appealed to the Sixth Circuit Court of Appeals, where he argued that the government violated his rights under the Fourth Amendment by obtaining and examining those records. The court ruled for the government, concluding that Carpenter had no reasonable expectation of privacy in cell phone location records. Carpenter asked the Supreme Court to hear the case, and it agreed to do so.

CAC filed a friend-of-the-court brief in the Supreme Court on behalf of scholars of the history and original meaning of the Fourth Amendment, arguing that the government violated Carpenter’s Fourth Amendment right to be protected from unreasonable searches and seizures. As we explain, obtaining and examining Carpenter’s cell phone records was a “search” in any normal sense of the word, and it is a “search” within the meaning of the Fourth Amendment. Further, we explain that entrusting government agents with unfettered discretion to conduct searches using cell site location information undermines the Fourth Amendment “right of the people to be secure . . . against unreasonable searches.” Indeed, although the Framers of the Fourth Amendment could not have anticipated cell-phone technology, they deliberately chose language that demonstrated their recognition of the dangers inherent in any state claim of unlimited authority to conduct searches for evidence of criminal activity. Finally, although there is a federal law called the Stored Communications Act that imposes some limits on the government’s access to certain information in cell phone records, that Act was enacted long before access to telephone records allowed comprehensive tracking of subscribers’ movements, and, as a consequence, it does not require sufficiently rigorous justifications for government access to this revealing data.

Case Timeline

More from Criminal Justice

Criminal Justice
U.S. Supreme Court

Timbs v. Indiana

In Timbs v. Indiana, the Supreme Court is being asked to consider whether state governments must comply with the Eighth Amendment’s prohibition against “excessive fines.”
Criminal Justice
U.S. District Court for the District of Massachusetts

Alasaad v. Nielsen

In Alasaad v. Nielsen, the district court for the District of Massachusetts is considering whether the First and Fourth Amendments permit law enforcement officers—without a warrant, probable cause, or even reasonable suspicion of illegal activity—to search...
Criminal Justice
November 30, 2017

Where Are We with Location Privacy? Reactions to the Supreme Court’s Oral Argument in Carpenter v. United States

Host: American Bar Association
The privacy of cell phone location information and free speech will be the focus of...
Participants: Elizabeth B. Wydra, Alan Jay Butler, Dan Schweitzer, Jake Laperruque
Criminal Justice
U.S. Court of Appeals for the Eleventh Circuit

Walker v. City of Calhoun

In Walker v. City of Calhoun, the United States Court of Appeals for the Eleventh Circuit is considering whether the City’s use of a secured money bail system for misdemeanor offenders violates the Equal Protection...
Criminal Justice
U.S. Supreme Court

Tyler v. United States

In Tyler v. United States, the Supreme Court is being asked to consider whether the Double Jeopardy Clause of the Fifth Amendment, which prohibits any person from being prosecuted for the same offense more than...
Criminal Justice
U.S. Supreme Court

Parker v. Montgomery County Correctional Facility

In Parker v. Montgomery County Correctional Facility, the Supreme Court was asked to hear a case that raises the question whether the “three strikes” provision of the Prison Litigation Reform Act prevents an indigent prisoner...