Enlarge / Protesters gather outside the Supreme Court for the No Muslim Ban on April 25, 2018 in Washington, DC. (credit: Tasos Katopodis/Getty Images for MoveOn.org) In a 5-4 decision issued Friday, the Supreme Court of the United States ruled that if the government wants to collect a suspect’s cell-site location information (CSLI)—detailed, granular data that shows where a person is every few seconds—it needs a warrant to do so. However, the court declined to overturn the controversial "third-party doctrine," the 1970s-era legal precedent that found there was no "reasonable expectation of privacy" in data collected by a third party, like a phone company.