Congressional hearings begin Monday on President Bush's decision to order, without warrants, eavesdropping on Americans with suspected ties to terrorists. Some lawmakers continue to question the legality of the program, despite a strong defense of the effort by Bush administration officials.
The Senate Judiciary Committee will be conducting the hearings. Its chairman, Senator Arlen Specter, a Pennsylvania Republican, has made no secret of his concern about the surveillance program, which was first revealed by the New York Times in December.
"When you got beyond the headline, starting with the headline that the president authorized these wiretaps, surveillance of citizens in the United States, that is wrong, and it cannot be condoned at all," he said.
President Bush signed an order in 2002 authorizing the eavesdropping on international phone calls and e-mails between people in the United States and suspected terrorists overseas. The program bypasses a special federal court whose approval is required under a 1978 law known as the Foreign Intelligence Surveillance Act - or FISA - for domestic eavesdropping operations.
Administration officials argue the president has the constitutional authority to order such wiretaps without warrants to protect national security. They also say Congress gave him authority to do so when it passed a resolution authorizing the use of force to respond to those responsible for the September 11, 2001 attacks on the United States - namely, the al-Qaida terrorist network led by Osama bin Laden.
Attorney General Alberto Gonzales is expected to say as much when he testifies before the committee on Monday. But he has made clear he would not talk about how the program is being conducted.
"The absolute worst thing we can do is to talk about the operational aspects of a highly classified program that has been very successful in protecting America, and to divulge all that information to the enemy," he said. "So what I am going to do is come before the Senate Judiciary Committee and talk about the legal authorities in connection with this the program."
But critics disagree with the administration's defense of the constitutionality of the surveillance program.
"The congressional authorization for the use of military force against Osama bin Laden did not authorize warrantless spying on Americans, as the Bush administration is now proclaiming," said Senator Patrick Leahy of Vermont, the top Democrat on the Judiciary Committee.
Other critics say the lack of judicial approval violates current law and the Constitution.
But Republican supporters of the program defend the need to bypass the court and warrants to allow for swift action against the new terrorist threats of the 21st century.
"The FISA law, the 1970s-era law was designed primarily to deal with agents, for example, of the Soviet Union," said Senator Jon Kyl, an Arizona Republican. "It was predicated on the kind of process we use in criminal courts, where you go swear out affidavits for a warrant, in this case, and then collect information. That kind of format is not suitable for the kind of technology that is used today by our intelligence community to gather large volumes of information in a real time situation, which cannot accommodate a lengthy and time consuming search warrant kind of procedure which is embedded in the FISA law."
Some lawmakers say legislation may be necessary to update the law.
President Bush says that would not only be unnecessary, but dangerous.
"My concern has always been that in an attempt to try to pass a law on something that's already legal, we'll show the enemy what we're doing," he said. "And we have briefed Congress - members of Congress. We'll continue to do that, but it's important for people to understand that this program is so sensitive and so important, that if information gets out to how it's - how we do it, or how we operate, it will help the enemy."
Intelligence officials say they want to see the program continue.
General Michael Hayden is principal deputy director of national intelligence, and former Director of the National Security Agency, which has been conducting the surveillance program. He addressed the issue at a public hearing of the Senate Intelligence Committee Thursday.
"This program has been successful," he said. "We have learned information from this program that would not have been available to us otherwise. This information has helped detect and prevent terrorist attacks in the United States and abroad."
The Director of the Central Intelligence Agency, Porter Goss, told the committee the disclosure of the program has undermined U.S. intelligence-gathering abilities, and called for a federal probe into who leaked the information.
The Intelligence Committee plans its own hearings on the issue in the coming weeks.