"The Broad Reach of Carpenter v. United States" by Paul Ohm was originally published June 27, 2018, on Just Security
Carpenter v. United States is an inflection point in the history of the Fourth Amendment. From now on, we’ll be talking about what the Fourth Amendment means in pre-Carpenter and post-Carpenter terms. It will be seen as being as important as Olmstead and Katz in the overall arc of technological privacy.
I hope to develop the argument that Carpenter is as important as Katz across two or three articles at Just Security, but let me begin with my overall big picture: The holding and reasoning of Carpenter is breathtakingly broad and will be applied far beyond the facts of this case. (For a detailed overview of the facts and five opinions of this case, see this blog post written by my star student and recent Georgetown graduate, Sabrina McCubbin.)
Carpenter holds that the police may not collect historical cell-site location information (CSLI) from a cellphone provider without a warrant. Footnote three (get used to a lot of scholarly commentary about Carpenter, footnote three!) restricts the holding, for now, to seven days of collection. I’ll write later ...