The New York Times Editorial Board: It was bad enough in 2008 when Congress allowed the agency to spy without a warrant on e-mails and text messages between Americans and foreign targets of an investigation. That already strained the Fourth Amendment’s protections against illegal searches, but lawmakers decided it was justified as part of a terror investigation.

It turns out, as Charlie Savage revealed in The Times on Thursday, that the N.S.A. went far beyond those boundaries. Instead, it copies virtually all overseas messages that Americans send or receive, then scans them to see if they contain any references to people or subjects the agency thinks might have a link to terrorists.

That could very well include innocent communications between family members expressing fears of a terror attack. Or messages between an editor and a reporter who is covering international security issues. Or the privileged conversation between a lawyer and a client who is being investigated.

Data collection on this scale goes far beyond what Congress authorized, and it clearly shreds a common-sense understanding of the Fourth Amendment. It’s as if the government were telling its citizens not to even talk about security issues in private messages or else they will come to the attention of the nation’s spies. “By injecting the N.S.A. into virtually every crossborder interaction, the U.S. government will forever alter what has always been an open exchange of ideas,” said Jameel Jaffer, the deputy legal director of the American Civil Liberties Union.

Obama administration officials justified this unwarranted expansion of surveillance powers with the usual hairsplitting arguments over semantics. It’s not “bulk collection” of messages if the messages aren’t stored, they said (even if every message is analyzed by supercomputers as it is sent). It’s legitimate to search through conversations “about” a target, even if the target isn’t part of the conversation. Naturally, the Foreign Intelligence Surveillance Court approved these half-baked assertions with a secret opinion.

The disclosure of this practice makes it more urgent than ever that Congress clamp down on what is unquestionably the bulk collection of American communications and restrict it to clear targets of an investigation. Despite President Obama’s claim this week that “there is no spying on Americans,” the evidence shows that such spying is greater than the public ever knew.