Carpenter v. United States and the Fourth Amendment: The Best Way Forward

38 Pages Posted: 29 Jun 2017 Last revised: 12 Apr 2018

See all articles by Stephen E. Henderson

Stephen E. Henderson

University of Oklahoma - College of Law

Date Written: 2017


We finally have a federal ‘test case.’ In Carpenter v. United States, the Supreme Court is poised to set the direction of the Fourth Amendment in the digital age. The case squarely presents how the twentieth-century third party doctrine will fare in contemporary times, and the stakes could not be higher. This Article reviews the Carpenter case and how it fits within the greater discussion of the Fourth Amendment third party doctrine and location surveillance, and I express a hope that the Court will be both a bit ambitious and a good measure cautious.

As for ambition, the Court must recognize that the fundamental liberty protected by the Fourth Amendment—the right to be “secure in [our] persons, houses, papers, and effects”—is squarely at issue when the government seeks to track our longer term movements, whether historically or prospectively. It is not business records, beepers, automobiles, phones, cameras, drones, or some other coincidental medium or technology that is at issue: it is our constitutionally protected liberty. Thus, the Court should hold that law enforcement acquisition of longer term cell site location information (CSLI) constitutes a Fourth Amendment search, ending the monolithic, anachronistic third party doctrine.

As to the precise durational trigger and as to what particular law enforcement restraint would be correspondingly reasonable, the Court should be cautious, as it was in United States v. Jones and Grady v. North Carolina. It will have taken the better part of a half century to undo the Court’s expansive third-party declaration in United States v. Miller, an unnecessary overreach best relegated to history. Thus, while the Court should not abandon Fourth Amendment development through reasonable reliance, it should remand these constitutional determinations for lower court development. Those courts should consider not only Fourth Amendment precedents, but also how state supreme courts have independently interpreted their own constitutions.

Keywords: fourth amendment, search, cell site location, privacy, carpenter, third party doctrine, surveillance

JEL Classification: K10, K14

Suggested Citation

Henderson, Stephen E., Carpenter v. United States and the Fourth Amendment: The Best Way Forward (2017). 26 Wm. & Mary Bill Rts. J. 495 (2017) , Available at SSRN:

Stephen E. Henderson (Contact Author)

University of Oklahoma - College of Law ( email )

300 Timberdell Road
Norman, OK 73019
United States
405.325.7127 (Phone)


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