On Friday, June 22, 2018, the United States Supreme Court ruled in a 5–4 decision that law enforcement must generally get a warrant in order to obtain an individual’s cell site location information. This blog explains the Carpenter v. United States[1] decision, as it has a monumental impact for millions of Americans.

To begin, I have always been amazed at how the high Court applies the Fourth Amendment in a society that continues to evolve.   In fact, I published an article in the South Dakota Law Review, titled, Paws Off My Porch: Sniffing Out Florida v. Jardines’ Effect on Drug Dogs and Homes, 59 S.D. L. Rev. 109 (2014) and covered the evolution of search and seizure law.  That article details how the Supreme Court applied the archaic, property-based search analysis to hold that a warrantless drug dog sniff of a home was unlawful.  But, Carpenter, in my opinion, is on the right track.  The Supreme Court moved beyond the rigid approach of Fourth Amendment law that has been following two steps behind advancements in technology.  Carpenter paves a way for everyone’s right to privacy beyond just our “papers and effects” and now explicitly extends to your smart phone. 

The Carpenter case centered around cell site location information (CSLI), which wireless carriers collect and store for business purposes.  Each time a phone scans for the best signal looking for a cell site—something your phone may do several times a minute, even if you are not actively using it—CSLI is generated.  The heart of the privacy issue with CSLI is the fact that it records the user’s geographic location.  Wireless carriers use this information for various reasons such as determining when to charge you for roaming services and even sell this information to data brokers (without sharing your identifying information, of course).

In Carpenter, law enforcement obtained the defendant’s CSLI without a warrant.  This amounted to 12,898 location points, an average of 101 a day.  Law enforcement was able to obtain that information under a federal statute called the Stored Communications Act, which only requires that the government prove “reasonable grounds” for believing an individual’s data is “relevant and material to an ongoing investigation.”  Using those location points, the government was able to argue that the defendant was involved in various robberies as he was near the scene of four crimes.  

On appeal, Carpenter argued that the government had violated his Fourth Amendment right to be free from unreasonable searches and seizures.  Carpenter, however, seemed to face an uphill battle against the “third-party doctrine,” a long-standing rule that an individual loses his or her right to privacy in information that is voluntarily given to a third party.  

In its opinion, the Supreme Court acknowledged that the third-party doctrine is not applicable to “these novel circumstances” and held that “an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through CSLI.”  Reiterating the hallmark of search and seizure law, Chief Justice Roberts explained that the Fourth Amendment “protects people, not places” and that society has a reasonable expectation of privacy in CSLI.  “[T]ime stamped data,” the Chief Justice wrote, “provides an intimate window into a person’s life, revealing not only his particular movements but through them, his familial, political, professional, religious, and sexual associations.”  As such, CSLI warrants constitutional protection.  Now, law enforcement must generally obtain a warrant—which requires a showing of probable cause—in order to access CSLI.  The Chief Justice acknowledged, however, that there may be exceptions to the warrant requirement, including proof of exigent circumstances (i.e., child abductions or bomb threats) or to capture fleeing suspects, just to name a few. 

Justices Kennedy, Thomas, Alito, and Gorsuch each wrote separate dissents, an unusual move that demonstrates their deep disagreement with the majority.  Justice Thomas and Justice Gorsuch complained on originalist grounds, protesting that the court had moved beyond what the Framers intended.  Then, Justice Alito complained that the majority had overreacted to new technology.  Finally, Justice Kennedy wrote that the court had “unhinge[d]” the Fourth Amendment “from the property-based concepts that have long grounded” its “analytical framework.” 

In conclusion, the Carpenter case presents new issues in criminal and privacy law, and those issues certainly may exceed the scope of this blog post.  If you have any questions about how the Supreme Court’s decision affects you, contact us for more information.


[1] 2018 WL 3073916, — S. Ct. —, No. 16–402 (June 22, 2018).