Merely turning on a cell phone creates a record. That record, which can be vast as we all keep our cell phones turned on all the time, is stored by our cell phone providers. Do you have a privacy interest in those records? Or can the police just obtain your records to track your movements without your consent, without your knowledge, and without a warrant?
Those issues present SCOTUS with another opportunity to update Fourth Amendment law to fit with present-day technology. Carpenter v. United States asks if a warrant is required to obtain historical cell phone records that revealed the location and movement of a cell phone. This is framed as a doctrinal challenge to whether third parties--such as cell phone companies--may voluntarily share digital information information with law enforcement.
The facts, in brief, are that law enforcement obtained several months worth of historical cell phone records from Mr. Carpenter's cell phone service provider (the third party) without a warrant. This information tracked Mr. Carpenter's cell phone and placed him (or, at least, his cell phone) in the vicinity of a string of robberies. This data was created by merely carrying, not using, an active cell phone. The government did not have a warrant but relied on statutory authority derived from the Stored Communications Act of 1986. The government argues that the defendant has no ownership interest in records provided by the third party cellphone service provider, and there is no Fourth Amendment protection because the records do not reveal the content of his calls.
Carpenter argues that the volume and precision of the data calls for a different analysis than, say, bank records. A cell phone user has little knowledge or control over the information produced as a result of having a cell phone. The Electronic Frontier Foundation has filed an amicus brief that provides data on the breadth and depth of information provided by cell phones, cell cites, and cell towers.
This presents a different issue than either United States v. Jones, 132 S.Ct. 945 (2012) (tracking the movements of a defendant based on information provided by a GPS device attached to his car is a search under the Fourth Amendment and will generally require a warrant) or Riley v. California, 134 S.Ct. 2473 (2014) (officers must generally obtain a warrant before searching the content of a lawfully seized cell phone). Here the Court may find law enforcement's activities less intrusive than Jones or Riley; a lessened expectation of privacy would allow a third party to release the records without a warrant.
On the other hand, Professor Orin Kerr argues that the third-party argument is in the "wrong doctrinal box." Instead, he compares this to the eyewitness rule: "If the Supreme Court sticks with the eyewitness rule, Carpenter v. United States is an easy case. Cellphone companies are eyewitnesses." Either way, the Court needs to confront the Fourth Amendment question in contemporary terms.
Note: Following Riley, the Tenth Circuit requires a warrant before law enforcement may search cell phone content.
Thanks to Scotusblog for the links.