There is considerable debate about the legality and constitutionality of the government's secret program to eavesdrop on phone calls and e-mail of terror suspects in the United States.
President Bush says he was given the legal authority to spy on U.S. citizens without a court order when Congress authorized the war in Afghanistan.
"It's consistent with the resolution by the congress after 9/11," Vice President Dick Cheney told ABC News' "Nightline" anchor Terry Moran.
While that law gives the president power to wage a military campaign against terrorism, it makes no reference to spying on U.S. citizens.
"There's nothing in the legislation to suggest that Congress authorized the president to eavesdrop on American citizens without judicial supervision," said Stephen Saltzburg, former deputy assistant attorney general under President Reagan and the first President Bush.
The president, however, says he is acting within the bounds of the Constitution.
"I have the constitutional responsibility and the constitutional authority to protect our country. Article II of the Constitution gives me that responsibility and the authority necessary to fulfill it," Bush said in a news conference today.
Article II of the Constitution grants the president the powers of commander in chief -- but legal scholars argue it says nothing about unbridled presidential power to eavesdrop.
"The founders of the Constitution understood profoundly that power corrupts and absolute power corrupts absolutely and they wanted to check it and they did," Saltzburg said.
The president said the House and Senate Intelligence Committees were briefed on the eavesdropping. But today Sen. Jay Rockefeller, D-W.Va. -- the ranking minority member of the Senate Intelligence Committee -- said the information provided was "limited" and that when he complained, his concerns "were never addressed."
The president said he needed the power to eavesdrop without a court order to streamline the process of wiretapping suspected terrorists.
"We've got to be fast on our feet, quick to detect and prevent," Bush said.
But the Foreign Intelligence Surveillance Act allows investigators to wiretap before getting a warrant, as long as they request permission from a special intelligence court within 72 hours.
"Doesn't hold water," said Saltzburg. "As long as you can act in emergencies before you get a court order, then speed is irrelevant here."
The secret court has overwhelmingly done the bidding of recent administrations. Since 1979, the Justice Department has gone before the secret court 18,742 times and has only been turned down in four instances.
But for the Bush administration, court approval, at times, was not fast enough.
ABC News' Pierre Thomas filed this report for "World News Tonight."