Carpenter v. United States, recently decided by the U.S. Supreme Court, is the first High Court decision to address “the ability to chronicle a person’s past movements through the record of his cell phone signals.”[i] The case arose when the federal government relied on a subpoena issued under the Stored Communications Act to obtain cell-site location information (CSLI) from Carpenter’s cell phone providers. The location data provided by the CSLI records was central to convicting Carpenter of robbery. Carpenter unsuccessfully argued both at trial and on appeal that the federal government was required to obtain a warrant under the Fourth Amendment to seize the CSLI records.
The High Court held that “an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through CSLI,”[ii] that the government’s acquisition of Carpenter’s CSLI records was a search and that “the Government must generally obtain a warrant supported by probable cause before acquiring such records.”[iii] Specifically addressing the decision’s application to third parties, the Court stated: “We hold only that a warrant is required in the rare case where the suspect has a legitimate privacy interest in records held by a third party.”[iv]
Although the Court indicated that the Carpenter decision is narrow, it is a notable decision in at least three ways:
1) it affirms that the Fourth Amendment protects privacy rights connected to people, not just privacy rights connected to property;
2) it rejects a mechanical application of the third-party doctrine; and
3) it recognizes that law enforcement now has the potential to access years of an individual’s location information that was collected before law enforcement even knew that it wanted to follow that individual.
Keep reading for more details on each of these intriguing topics. Continue reading “Cell Phone Owners Have a Reasonable Expectation of Privacy in Their Historical Location Data”