U.S. District Judge Anna Diggs Taylor in Detroit became the first judge to strike down the National Security Agency's program, which she says violates the rights to free speech and privacy as well as the separation of powers enshrined in the U.S. Constitution.
"Plaintiffs have prevailed, and the public interest is clear, in this matter. It is the upholding of our Constitution," Taylor wrote in her 43-page opinion.
The Bush administration immediately appealed the ruling, and the parties in the lawsuit have agreed to a delay of the injunction to stop the surveillance until they can argue before Judge Taylor for a stay pending appeal, CBS News producer Beverley Lumpkin reports.
U.S. Attorney General Alberto Gonzales said the surveillance program has been "very effective" in protecting Americans.
"We believe very strongly that the program is lawful. ...," Gonzales said in Washington. "We respectfully disagree with the decision of the judge and have appealed the decision."
The government argued that the program is well within the president's authority, but said proving that would require revealing state secrets.
The ACLU said the state-secrets argument was irrelevant because the Bush administration already had publicly revealed enough information about the program for Taylor to rule.
"At its core, today's ruling addresses the abuse of presidential power and reaffirms the system of checks and balances that's necessary to our democracy," ACLU executive director Anthony Romero said in a conference call with reporters.
He called the opinion "another nail in the coffin in the Bush administration's legal strategy in the war on terror."