The Supreme Court’s 9-0 opinion that the police may not, without a warrant, “search digital information on a cell phone seized from an individual who has been arrested,” is an occasion for defenders of the Fourth Amendment to dance in the streets. Chief Justice Roberts’s majority opinion went further than even the most ardent friends of privacy had expected. “The Court made clear that the exceptions to the Fourth Amendment, carved out in the pre-digital era, are no longer tenable,” I was told by Marc Rotenberg of the Electronic Privacy Information Center, whose brief Roberts’s sympathetically cited. “Chief Justice Roberts even suggested that the search of a cell phone could be more intrusive than the search of a home.” As Jeffrey Fisher of Stanford Law School, the lawyer for the arrested suspect told me after the case came down, “The decision brings the Fourth Amendment into the digital age.”

On June 16, Fisher and Edward C. Dumont, the Solicitor General of California who argued the Riley case on the other side for the government, came to the National Constitution Center (where I’m president and CEO) for a debate about the stakes in the case. As the podcast of their debate makes clear, neither of the opposing lawyers anticipated such a sweeping victory for privacy. “The police need a simple, categorical, bright-line rule that they can apply in the field, and here, the bright-line rule is: if you have something on your person, the police can take a look at it and see whether it’s something that’s either dangerous or that is evidence of crime,” said Ed DuMont.

In response, Jeffrey Fisher compared searches of cell phones to the writs of assistance and general warrants that sparked the American Revolution.“[You can’t] very often say this in the Supreme Court, but it was actually one of the core rallying cries for the Constitution and for the Revolution,” Fisher said. “If an officer is able to look at the digital information on this device without obtaining a warrant, they’re conducting essentially the exact kind of search that was prohibited at the Founding—indeed, you might even think it’s more intrusive because unlike searching throughout somebody’s entire home, for example, on an arrest, a cellphone also gives a search of their doctor’s office, a search of their financial advisor, a search of their medicine cabinet, you can keep going—we think that that is reason why the Court, as a historical matter and a modern, pragmatic matter, should say that digital information is different.”

Dumont rejected the historical analogy. “I don’t think this is like writs of assistance,” he said. “You’re already in a completely different world than the writs of assistance because you’re talking about somebody who has been validly arrested for a particular crime.”

In his inspiring majority opinion, Chief Justice Roberts not only accepted Fisher’s analogy between cell phone searches and the writs of assistance: He eloquently extended it: