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Law School Case Brief

Carpenter v. United States - 138 S. Ct. 2206 (2018)


Given the unique nature of cell phone location records, the fact that the information is held by a third party does not by itself overcome the user’s claim to Fourth Amendment protection. Whether the Government employs its own surveillance technology or leverages the technology of a wireless carrier, an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through cell-site location information.


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 Stored Communications Act. 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 Fourth Amendment. 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.


Did the government violate petitioner’s right to privacy when they accessed his CSLI without a warrant?




The government's acquisition from wireless carriers of defendant's historical CSLI was a search under the Fourth Amendment. When the government accessed defendant's CSLI, it invaded his reasonable expectation of privacy in the whole of his physical movements, and the fact that the government obtained the information from a third party did not overcome defendant's claim to Fourth Amendment protection. A court order obtained by the government under the Stored Communications Act, 18 U.S.C.S. § 2703(d), was not a permissible mechanism for accessing historical CSLI because the showing required under the Act fell well short of probable cause. A warrant was necessary to obtain CSLI in the absence of an exception such as exigent circumstances.

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