Law enforcement officials wanted to learn where Petitioner Timothy Carpenter was at the time of certain robberies. To figure that out, they obtained records from his cellular service provider showing the movements of his cell phone. Examining those records, they were able to track Carpenter’s whereabouts over a four-month period. Obtaining and examining those records was a “search” in any normal sense of the word—a search of documents and a search for Carpenter and one of his personal effects. It was therefore a “search” within the meaning of the Fourth Amendment. When the Amendment was ratified, to “search” meant to “examine,” “explore,” “look through,” “inquire,” “seek,” or “try to find.” Samuel Johnson, A Dictionary of the English Language (10th ed. 1792). Nothing about the text of the Fourth Amendment, or the historical backdrop against which it was adopted, suggests that the term “search” should be construed more narrowly in that Amendment to mean only conduct violating “an actual (subjective) expectation of privacy” that “society is prepared to recognize as ‘reasonable.’” Katz v. United States, 389 U.S. 347, 361 (1967) (Harlan, J., concurring). Plainly, by examining and looking through Carpenter’s cell site location records to seek the whereabouts of his person and phone, the government agents in this case conducted a “search.”
Although those who drafted and ratified the Fourth Amendment could not have anticipated cellphone technology, they would have recognized the dangers inherent in any state claim of unlimited authority to conduct searches for evidence of criminal activity. Cell site location information provides insight into where we go and what we do—potentially revealing one’s intimate relationships, hobbies, predilections, medical conditions, religious beliefs, and political pursuits. Because this information is constantly generated and can be retrieved by the government long after the activities it memorializes have taken place, unfettered government access to cell site location information raises the specter of general searches and undermines the security of “the people.”
Margaret Hu et al., Brief of Scholars of the History and Original Meaning of the Fourth Amendment as Amici Curiae in Support of Petitioner, Carpenter v. United States, No. 16-402 (U.S. Aug. 14, 2017).