In a 5-4 decision issued last week, the United States Supreme Court held police must obtain a search warrant before seeking data showing the location of cell phone users. Importantly, this is the third in a series of rulings limiting police access to digital data. Writing for the majority in Carpenter v. U.S., Chief Justice John Roberts noted: “When the government tracks the location of a cell phone it achieves near perfect surveillance, as if it had attached an ankle monitor to the phone’s user.” The Chief Justice further recognized that signal towers and processing centers that track cell phone users “are ever alert, and their memory is nearly infallible.”
Under that rationale, the majority held that the prior case law precedent the prosecutor cited to justify warrentless searches were outdated and inapplicable.
But the decision also emphasized that exceptions to the warrant requirement remained applicable to location data, especially in emergencies:
“Lower courts, for instance, have approved warrentless searches related to bomb threats, active shootings, and child abductions. . . Our decision today does not call into doubt warrentless access in such circumstances.”
Writing in a separate dissent, Justice Samuel Alito disagreed stating: “The desire to make a statement about privacy in the digital age does not justify the consequence that today’s decision is likely to produce.”
Lawyers for the American Civil Liberties Union, which represented Mr. Carpenter before the Supreme Court, described the decision as a “truly historic vindication of privacy rights.”