Carpenter v. United States – Warrantless Access to Cellphone Location Data

In Carpenter v. United States, the Supreme Court will consider whether the government must obtain a warrant before accessing the rich trove of data that cellphone providers collect about their users’ movements. The Court’s resolution of the case is likely to have far-reaching implications for privacy as well as for the freedoms of speech, press, and association.

Cellphone providers routinely record detailed information about the locations of their users as they use their phones. Today, the location data rivals the precision of GPS systems. The data recorded is extraordinarily rich and can be used, for example, to determine whether someone went to an Alcoholics Anonymous meeting, an abortion clinic, or the office of an attorney who represents government whistleblowers. Law enforcement agencies are increasingly requesting cellphone location information from cellular service providers, with AT&T receiving close to 60,000 requests in 2015 alone. Officials are obtaining this data without first obtaining warrants, and without broad public awareness that cellphone providers even possess it.

Leading technology experts represented by the Knight First Amendment Institute filed an amicus brief with the Supreme Court, arguing that the Fourth Amendment prohibits the government from obtaining cellphone location data without a warrant.