The words “National Security Agency” appear nowhere in the Supreme Court’s opinion Wednesday prohibiting cellphone searches without a warrant. But the unanimous ruling makes clear that the nation’s most important jurists are tuned in to the roiling debate about high-tech surveillance and concerned about government officials going too far.

In broad, passionate language — spiked with the occasional joke — the ruling by Chief Justice John G. Roberts Jr. asserts that the vast troves of information police can find in modern cellphones are no less worthy of constitutional protection than the private papers that Founding Fathers once kept locked in wooden file cabinets inside their homes.

Roberts even chides the government for arguing that searching a cellphone is “materially indistinguishable” from searches of other items that can be seized at the scene of an arrest, such as a pack of cigarettes or a handwritten note. “That is like saying a ride on horseback is materially indistinguishable from a flight to the moon. Both are ways of getting from point A to point B, but little else justifies lumping them together,” he wrote.

Such declarations, experts said, suggest a willingness to reconsider legal rulings long used to justify modern surveillance tools. That includes some spying technologies that were unimaginable when courts first articulated those arguments but that now are routinely used by a range of government agencies, including the NSA, the FBI and many state and local police forces.

A footnote in Wednesday’s ruling cautions against assuming too much about the court’s views on data collection “under other circumstances.” But legal experts on both sides of the privacy debate took notice of the unanimity of the ruling and the uncommonly strong language Roberts used when describing the privacy risks in modern technologies.

“It’s just a big, forceful, bold decision,” said Orin S. Kerr, a George Washington University law professor and former Justice Department lawyer specializing in technology issues. “If you’re at the [American Civil Liberties Union], you’re popping a champagne bottle. If you’re at the FBI, you’re scratching your head and thinking of what you’re going to do next.”

Many observers date the Supreme Court’s reconsideration of high-tech surveillance to the United States v. Jones decision in 2012, which ruled that police had trespassed when placing an electronic tracking device on a suspect’s car. In applying a traditional constitutional protection to new technology, the court expressed concerns about the need to update the Fourth Amendment for the modern world.

The ruling on cellphone searches, experts said, suggested that the court’s consensus has grown on such issues over the past two years, a period in which the revelations made by former NSA contractor Edward Snowden have sparked international controversy over the privacy implications of high-tech government spying.

The Supreme Court ruling, said former NSA general counsel Stewart A. Baker, “shows that the judges have the same technology panic that the rest of us do.”

Baker, now a partner at a private law firm, added, “That means that in other areas they also will be alive to that risk and open to arguments that the rules should be changed.”

Privacy advocates are likely to cite the ruling in seeking to limit the ability of the government to conduct searches in border areas, where constitutional standards typically are lower. Even the “third-party doctrine,” which says that users have no reasonable expectation of privacy when they share information with a company or other third party, could be put in peril.

In Wednesday’s ruling, Roberts notes that cellphones aren’t exclusively — or even mainly — devices for talking, given their ability to also shoot video, browse the Web, send and receive e-mail, store gigabytes of information and access even more of it through remote “cloud” services. He even makes a quip about how frequently people gaze at or touch the devices, saying that they are “such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude they were an important feature of human anatomy.”

The legal consequences of the ruling stand to go far beyond cellphones and into the increasingly broad array of devices that carry or can access personal information through digital means — computers, cars, e-readers, wearable devices such as Google Glass and even some newer appliances that track usage and can be accessed remotely over the Internet.

More than anything, legal experts said, the ruling offers a reminder that Supreme Court justices live in the real world and almost certainly use cellphones in ways that make them aware of their privacy risks.

“These are highly intelligent individuals who are engaged in the world around them,” said Brian Owsley, a former magistrate judge from Texas who repeatedly wrestled with technology and privacy issues during his years on the bench. “Any time you get nine people on the Supreme Court saying something in one direction, that’s pretty impressive. . . . They’re all clearly taking a stand for the Fourth Amendment in light of privacy concerns.”

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