Supreme Court Decides Search Warrant Generally Needed for Cellphone Location Data

no cellphones symbol On June 22, a Supreme Court decision decided that a search warrant will generally be needed to obtain cellphone location data.

By Christopher Zoukis

In Carpenter v. United States, the Supreme Court decided on June 22 that police will generally need a search warrant backed by a showing of probable cause to obtain cellphone location data showing a defendant’s location at any given time. Ironically, Timothy Carpenter’s appeal arose from his conviction for a series of armed robberies of T-Mobile and Radio Shack stores in Michigan and Ohio over a four-month period in 2010-11.

After the FBI identified cell phone numbers belonging to Carpenter and some confederates, prosecutors without a search warrant obtained months of automatically provider-generated data from the cell phone providers showing the time, data and location when those cellphones connected with a wireless network. At Carpenter’s trial, prosecutors used that cellphone location data as evidence to show on four occasions, Carpenter’s cell had been near a robbery location at the time of the crime.

Although Carpenter’s lawyers sought to block that evidence, the government argued it was within a “third-party” exception, provided by the Stored Communications Act. As amended in 1994, that law permits warrantless access to “business records” shared with a third-party, if “specific and articulable facts” can be shown that give reasonable grounds to believe the records are “relevant and material” to a current criminal investigation.

Sentenced to 116 years in prison for the robberies and related firearms charges, Carpenter, with assistance from the American Civil Liberties Union, filed an unsuccessful appeal to the Cincinnati-based 6th Circuit federal appellate court.

But the Supreme Court’s 5-4 majority opinion, written by Chief Justice John Roberts Jr. and joined by the Court’s four liberal-leaning justices (Breyer, Ginsburg, Kagen and Sotomayor), held cellphone location data can provide the government almost perfect surveillance of a defendant’s past whereabouts, and so constitute a “search” covered by the Fourth Amendment.

Not only a search, the Chief Justice continued, but one in which a defendant would have a reasonable expectation of privacy. He distinguished a cell-site location search from searches for other types of business records to which the Stored Communications Act’s “third-party” exception would apply.

Unlike some other third-party business records, cellphone location data not only reveals information for which a defendant would expect privacy, but the automatically generated time and location data neither requires or requests a cellphone user’s explicit consent to its being shared with the cell phone provider. For those reasons, the mere fact a cellphone provider is a third party is not enough to overcome a defendant’s Fourth Amendment privacy expectations, Chief Justice Roberts reasoned.

At the same time, he cautioned his opinion should be read narrowly. It was not meant to weaken prosecutors’ ability to use less pervasive surveillance tools or methods, such as security cameras, or to add new access restrictions to other third-party records capable of revealing location or to apply to data collections tools used in the areas of national security or foreign relations.

The four dissenting justices each wrote an opinion, with all but Justice Gorsuch joined by one or more of the other dissenters. Justice Kennedy called the majority opinion a “stark departure” from earlier Fourth Amendment cases, two other dissenters (Thomas and Alito) favor overturning a key 1967 search-and-seizure decision, and Justice Gorsuch would jettison the third-party exclusion and seek more definite standards for privacy rights.

Christopher Zoukis is the author of Federal Prison Handbook: The Definitive Guide to Surviving the Federal Bureau of Prisons, (Middle Street Publishing, 2017), and College for Convicts: The Case for Higher Education in American Prisons (McFarland & Co., 2014). He regularly contributes to New York Daily NewsPrison Legal News and Criminal Legal News. He can be found online at and