Landmark Decision – Police Must Have a Warrant for Cell Phone Location Data

By Samantha M. Vasques, & July 19, 2018Cyber Law

Is your cell phone nearby? Are you reading this article on it right now? It’s probably no surprise to you that Americans are with their cell phones constantly. And, you may already know that your cell phone is constantly scanning for the best signal. What you may not know is that in the process, your cell phone connects to cell sites and generates a time-stamped record of that connection: cell-site location information (CSLI). That CSLI tells a story about all of your comings and goings, tracing back up to five years. In a landmark decision issued this term, Carpenter v. United States, No. 16-402 (June 22, 2018), the Supreme Court held that the government’s access of CSLI was a search under the Fourth Amendment and, therefore, required a warrant.

Carpenter involved a criminal defendant whose movements over approximately three months were captured by CSLI held by two cell phone service providers. The government obtained that data from the providers (without a warrant) and used it to help convict the defendant of robbery, pointing out that he was physically close to four of the robberies while they were taking place, and relying on his CSLI to do so.

In the past, the Supreme Court has held that there is no reasonable expectation of privacy in information voluntarily shared with third parties. That’s common sense—if one posts a yard sign saying “I robbed the bank,” I don’t have a reasonable expectation that the information would stay private. Likewise, it wouldn’t be a “search” if a police officer stood outside one’s house and read the sign.

But the Supreme Court concluded that CSLI is different. Not only are cell phones “indispensable to participation in modern society,” the Court said, apart from disconnecting one’s phone entirely, there is no way to avoid leaving behind the trail of location data. Could anyone really be said to voluntarily assume the risk of turning over what the Court called a “comprehensive dossier” of one’s physical movements? The Carpenter majority didn’t think so. Peering into the vast trove of location data stored by cell phone providers constituted a “search” in the Court’s eyes, and a warrant would be needed as a consequence. That’s a relief for the millions of Americans who—as the Court cheekily observed in another case—see their cell phone as “a feature of human anatomy.”


Disclaimer: This blog post is for informational purposes only. This blog is not legal advice and you should not use or rely on it as such. By reading this blog or our website, no attorney-client relationship is created. We do not provide legal advice to anyone except clients of the firm who have formally engaged us in writing to do so. This blog post may be considered attorney advertising in certain jurisdictions. The jurisdictions in which we practice license lawyers in the general practice of law, but do not license or certify any lawyer as an expert or specialist in any field of practice.

Back to Blog
Samantha M. Vasques is an Associate with Pannone Lopes Devereaux & O'Gara LLC and a member of the Estate and Trust Planning, Administration and Litigation, Corporate & Business and Litigation Teams. She concentrates her practice on providing legal support, advocacy and counsel representing clients including performing pre-trial investigation and discovery, and motions and pleadings preparation through trial, settlement and the appeal process. Attorney Vasques is the co-author of "A New Hope: Tortious Interference with an Expected Inheritance in Rhode Island," which was published in the Roger Williams University Law Review.

She earned her J.D., summa cum laude, from Roger Williams University School of Law, and was Assistant Editor of the Law Review (2013-2014). She is a recipient of CALI Excellence for the Future Awards in several subjects, including in Business Planning, Contracts, Evidence, Property and Sales. Attorney Vasques also served as a Judicial Law Clerk for the Honorable Justice William P. Robinson III of the Rhode Island Supreme Court and as a Judicial Extern for the Honorable O. Rogeriee Thompson of the United States Court of Appeals for the First Circuit in Providence, RI. She graduated with a B.A. in Economics from the University of Massachusetts at Amherst, summa cum laude. Attorney Vasques is admitted to practice law in Massachusetts and Rhode Island and is a member of the Board of the Rhode Island Women's Bar Association and a member of the Rhode Island Bar Journal Editorial Board.

Leave a Reply