After three days of a Bush administration offensive and weeks of debate and accusations, some legal experts are coming to terms on what is illegal and what is not in the National Security Agency electronic surveillance program.
"When the president goes around and speaks ... and says we're monitoring calls from overseas from Al Qaeda to the United States, the NSA can go ahead and do that now under the law," Sen. Edward Kennedy, D-Mass., said after the Senate Judiciary confirmation hearing of Supreme Court nominee Samuel Alito.
But Kennedy said independent organizations, like the Congressional Research Service, have studied the legality of the NSA program and say the president has gone beyond what the rules allow. Bush, however, says the eavesdropping program is legal and doesn't overstep the boundaries allowed to him by the Constitution and congressional resolution.
"These tools include surveillance to protect and prevent further attacks by our enemies," Bush said Wednesday after visiting the NSA to give a morale boost to workers there. "I have the authorization both from the Constitution and the Congress to undertake this vital program. The American people expect me to protect our lives and our civil liberties and that's exactly what we're doing with this program."
On Monday, the president described exactly what the NSA is doing.
"What I'm talking about is the intercept of certain communications emanating between somebody inside the United States and outside the United States and one of the numbers would be reasonably suspected to be an Al Qaeda link or affiliate," Bush told an audience at Kansas State University.
He added that just because the United States hasn't been hit in more than four years, the threat persists.
"Listen to the words of Usama bin Laden and take them seriously when he says he's going to hurt the American people again -- or try to -- he means it," Bush told reporters. "I take it seriously and the people of NSA take it seriously and most of the American people take it seriously, as well.
"This enemy still wants to do harm to the American people. We cannot let the fact that we have not been attacked lull us into the conclusion that the terrorists have disappeared. They have not disappeared," he said.
According to legal experts, hypothetically, if the NSA had intercepted calls from alleged terrorists such as Khalid Sheikh Mohammed or Ramzi Binalshibb, both now in custody, while they were abroad, then U.S. intelligence agents could listen to the calls without a warrant. That goes for phone calls with people on the other end of the line who happen to be in United States.
Only when the person inside the United States becomes the target of surveillance is a warrant from the Foreign Intelligence Surveillance court required.
"You wouldn't need a warrant to do the initial interception, but afterwards, once you're targeting the American citizen, then you need that warrant," said Bruce Fein, a former official in the Reagan Justice Department and a fierce critic of the Bush' administration's terror surveillance.
Other experts agree that a warrant is not needed until the U.S.-based individual becomes a suspect.
"If ... you are not targeting the person in the United States, you get the conversations, you are perfectly free to use those, that information provide it to other government agencies, if you want," said Bryan Cunningham, a former official with the Bush National Security Council.
Once the government agencies are given the information, they can open investigations with warrants to conduct further surveillance.
But others argue that the law says domestic communications monitoring rules apply even when only one end of the call is on U.S. soil. They say that's why Bush signed a highly classified directive approving the program and has to re-approve it every 45 days.
Current and former government officials familiar with electronic monitoring say that accidental eavesdropping — so-called "incidental intercepts" — are also a dark part of the business. When it happens, the NSA has procedures to protect the identities of Americans and their privacy.
Lt. Gen. Michael Hayden, the former head of the NSA at the time the president first authorized surveillance of terrorists, addressed that issue and others in a speech at the National Press Club on Monday.
"When you're talking to your daughter at state college, this program cannot intercept your conversations. And when she takes a semester abroad to complete her Arabic studies, this program will not intercept your communications," Hayden said.
He added that it would be impossible to monitor all phone calls between the United States and abroad because in 2003 alone, Americans participated in 200 billion minutes of international calls.
"The purpose of all of this is not to collect reams of intelligence, but to detect and prevent attacks. The intelligence community has neither the time, the resources nor the legal authority to read communications that aren't likely to protect us. And NSA has no interest in doing so. These are communications that we have reason to believe are Al Qaeda communications," Hayden said.
Critics say they don't believe Bush or administration officials when they say the program is limited. Sen. Dick Durbin, D-Ill., said Wednesday that Senate Democratic leaders as well as Kennedy and Russ Feingold of Wisconsin have signed a letter to Bush outlining their concerns with the program and the fact that they know very little about it.
Durbin noted that while an emergency exception to current law allows domestic wiretaps without court approval in the case of an emergency, it should not be the norm that the court is circumvented.
"This is not about whether we should wiretap terrorists. Democrats believe we should use every legal resource we have to put an end to Usama bin Laden's deadly franchise," Durbin said. "It isn't a matter of missing an opportunity; the government can act instantly to deal with a wiretap on a suspected terrorist and has 72 hours to contact the [FISA] court and advise them of the action that's been taken. If the president thinks the current laws are inadequate to wiretap terrorists, he should come to Congress."
Durbin said most lawmakers only know what the media has been reporting about the program. Although it appears from those reports that the president has gone beyond his authority, Durbin said, he's waiting to make his own judgment on that.
"I'd like to, before I reach that point, at least know how the program is being used," he said. "I'm not sure any member is looking for political confrontation. We want to establish a legal framework to keep America safe. I am concerned on a constitutional basis this president is saying, 'I don't need a political framework.' And that, I think, goes too far."
Sen. Chuck Schumer, D-N.Y., echoed complaints about how the president created the program but not about its importance. Defending Congress' oversight responsibilities and the need for civil liberties protections, Schumer said he worried about abuses similar to those before the Foreign Intelligence Surveillance Act was enacted in 1978.
"My view has generally been that when the president needs powers to protect us, he ought to get them, but there ought to be debate and it ought to be done with safeguards in place so that there aren't abuses, which we've seen in other wiretaps such as in the days of (J. Edgar) Hoover," Schumer said.
The latest Gallup Poll, taken just before the administration's public relations blitz this week shows a slight majority, 51-46, thinks the administration was wrong to allow warrantless wiretapping. The 5 percent difference is equal to the survey's margin of error.
After a Justice Department briefing Wednesday for former government officials on the president's so-called "terrorist surveillance program," former FBI and CIA Director William Webster, who served under Republican and Democratic presidents, expressed his support.
Asked if the U.S. government has done its due diligence regarding the law and civil liberty protections, Webster said, "I'm confident that we're, that they do have their act together."
Former CIA Director James Woolsey sides with the president, but recently said it's a close call.
"If anyone says it's a crystal clear issue one way or another, that is the only position I regard as wrong," he said.
All kinds of congressional hearings have been demanded regarding the program. The only one scheduled to date is on Feb. 6 by the Senate Judiciary Committee where Attorney General Alberto Gonzales is scheduled to testify.
On Wednesday, Committee Chairman Sen. Arlen Specter, R-Pa., sent Gonzales a letter with 15 opening questions on the legality of the communications intercepts, and he warned that the committee would want to question him the entire day.
"Would you consider seeking approval from the FISA court at this time for the ongoing surveillance program at issue? ... Why did the White House not ask Congress for changes to a 1978 foreign surveillance law? ... Why didn't the administration go to an established intelligence court to get approval for the monitoring?" are some of the questions asked by Specter.
Democrats say they want to see the committee call more witnesses than now planned, including former Attorney General John Ashcroft Deputy Attorneys General James Comey and Larry Thompson and White House Chief of Staff Andrew Card.
FOX News' Jim Angle, Carl Cameron and Liza Porteus and The Associated Press contributed to this report.