Carpenter v. United States Case Brief

Facts of the Case

Each time a phone connects to a cell site, it generates a time-stamped record known as cell-site location information (CSLI). Wireless carriers collect and store this information for their own business purposes. After the FBI identified the cell phone numbers of several robbery suspects, prosecutors were granted court orders to obtain the suspects’ cell phone records under the. Wireless carriers produced CSLI for petitioner Timothy Carpenter’s phone, and the Government was able to obtain 12,898 location points cataloging petitioner’s movements over 127 days—an average of 101 data points per day. Petitioner moved to suppress the data, arguing that the Government’s seizure of the records without obtaining a warrant supported by probable cause violated the. The District Court denied the motion, and prosecutors used the records at trial to show that Carpenter’s phone was near four of the robbery locations at the time those robberies occurred, leading to petitioner’s conviction. The Sixth Circuit affirmed, holding that Carpenter lacked a reasonable expectation of privacy in the location information collected by the FBI because he had shared that information with his wireless carriers.


Does the Fourth Amendment’s automobile exception permit a police officer without a warrant to enter private property in order to search a vehicle parked a few feet from the house?


“The government’s warrantless acquisition of Carpenter’s cell-site records violated his Fourth Amendment right against unreasonable searches and seizures. Chief Justice John Roberts authored the opinion for the 5-4 majority. The majority first acknowledged that the Fourth Amendment protects not only property interests, but also reasonable expectations of privacy. Expectations of privacy in this age of digital data do not fit neatly into existing precedents, but tracking person’s movements and location through extensive cell-site records is far more intrusive than the precedents might have anticipated. The Court declined to extend the “third-party doctrine”—a doctrine where information disclosed to a third party carries no reasonable expectation of privacy—to cell-site location information, which implicates even greater privacy concerns than GPS tracking does. One consideration in the development of the third-party doctrine was the “nature of the particular documents sought,” and the level of intrusiveness of extensive cell-site data weighs against application of the doctrine to this type of information. Additionally, the third-party doctrine applies to voluntary exposure, and while a user might be abstractly aware that his cell phone provider keeps logs, it happens without any affirmative act on the user’s part. Thus, the Court held narrowly that the government generally will need a warrant to access cell-site location information.Justice Anthony Kennedy filed a dissenting opinion, in which Justices Clarence Thomas and Samuel Alito joined. Justice Kennedy would find that cell-site records are no different from the many other kinds of business records the government has a lawful right to obtain by compulsory process. Justice Kennedy would continue to limit the Fourth Amendment to its property-based origins.Justice Thomas filed a dissenting opinion, emphasizing the property-based approach to Fourth Amendment questions. In Justice Thomas’s view, the case should not turn on whether a search occurred, but whose property was searched. By focusing on this latter question, Justice Thomas reasoned, the only logical conclusion would be that the information did not belong to Carpenter.Justice Alito filed a dissenting opinion, in which Justice Thomas joined. Justice Alito distinguishes between an actual search and an order “merely requiring a party to look through its own records and produce specified documents”—with the former being far more intrusive than the latter. Justice Alito criticizes the majority for what he characterizes as “allow[ing] a defendant to object to the search of a third party’s property,” a departure from long-standing Fourth Amendment doctrine.Justice Gorsuch filed a dissenting opinion in which he emphasizes the “original understanding” of the Fourth Amendment and laments the Court’s departure from it.”

Case Information

Citation: 585 US (2018)
Granted: Jun 5, 2017
Argued: Nov 29, 2017
Decided: Jun 22, 2018
Case Brief: 2018