Four days after President Bush signed controversial legislation legalizing some warrantless surveillance of Americans, the administration is citing the law in a surprise motion today urging a federal judge to dismisss a lawsuit challenging the NSA spy program.

The lawsuit was brought by lawyers defending Guantanamo Bay prisoners. The lawyers and others alleged the threat of surveillance is chilling their First Amendment rights of speech, and their clients' right to legal representation.

Justice Department lawyers are asking (.pdf) U.S. District Judge Vaughn Walker to toss the case, citing the new law -- which says warrantless surveillance can continue for up to a year so long as one person in the intercepted communications is reasonably believed to be located outside of the United States.

The motion is set to be heard in federal court in San Francisco this afternoon. THREAT LEVEL will be there.

The government said the new Protect America Act of 2007 requires the government to notify the secret Foreign Intelligence Surveillance Court "as soon as practicable" when somebody is being spied upon, but does not require its immediate authorization.

The government has maintained all along that electronic eavesdropping was legal, and said the newest legislation provides "an additional basis for dismissal."

The Center for Constitutional Rights, the plaintif in the lawsuit, is expected to argue today that the new law violates the Fourth Amendment's requirement that judges approve warrants for surveillance.

"Congress has ceded further power to an administration that has done nothing but abuse its power and betray the trust of the American people, center attorney Shayana Kadidal said. "Congress has given the president and attorney general virtually uncheckmed power to spy on international calls of Americans without any oversight or accountability from the courts."

Cindy Cohn, director of the Electronic Frontier Foundation, said the latest legislation does not apply to another eavesdropping case in which her group accuses AT&T of cooperating with the National Security Agency to make all communications on AT&T networks available to the spy agency without warrants. That case will be argued before the San Francisco-based 9th U.S. Circuit Court of Appeals on Thursday.

"This new law does not apply to this dragnet style of eavesdropping, and if it did, it's not retroactive," Cohn said.