A federal judge has declared the Bush administration's warrantless domestic surveillance program unconstitutional and ordered an immediate halt to it, according to the Associated Press.

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 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 American Civil Liberties Union filed the lawsuit on behalf of journalists, scholars and lawyers who say the program has made it difficult for them to do their jobs. They believe many of their overseas contacts are likely targets of the program, which involves secretly listening to conversations between people in the U.S. and people in other countries.

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 had already publicly revealed enough information about the program for Taylor to rule on the case.

"By holding that even the president is not above the law, the court has done its duty," said Ann Beeson, the ACLU's associate legal director and the lead attorney for the plaintiffs.

The NSA had no immediate comment on the ruling.

Taylor dismissed a separate claim by the ACLU over data-mining of phone records by the NSA. She said not enough had been publicly revealed about that program to support the claim and further litigation could jeopardize state secrets.

Beeson predicted the government would appeal the ruling and request that the order to halt the program be postponed while the case makes its way through the system. She said the ACLU had not yet decided whether it would oppose such a postponement.