Rice already has spoken before the commission, but in private and not under oath. The chairman of the panel, Thomas Kean, the former governor of the eastern state of New Jersey, says he wants further testimony from her, in public, to help assure the American people that their government was doing its best to protect them from terrorist attacks. Her testimony is expected as early as next week.
The issue became more urgent last week with the testimony of former White House counterterrorism official Richard Clarke, who said in a newly published book and in public testimony before the commission that the Bush administration did not take the threat of terrorism sufficiently seriously before 11 September 2001.
Rice appeared on many television and radio programs to counter Clarke's assertions. But said she could not make these same statements under oath before the commission because of an important constitutional principle. On the American television news program "60 Minutes," broadcast on 28 March, she said, "Nothing would be better from my point of view than to be able to testify. I would really like to do that, but there is an important principle involved here -- it is a long-standing principle that sitting national security advisers do not testify before the Congress."
But less than 48 hours later, she and the White House relented. Asked about the motivation, Kean told reporters yesterday, "I suspect that the president and the White House understood that it was very important for the public, as well as for the commission's work, that Dr. Rice be allowed to testify in public, and we recognize the important constitutional principal that the president was talking about, and the White House [was talking about], and we support that principle of presidential privilege very strongly as commissioners. But we also recognize the fact that this is an extraordinary event in human history."
The debate over Rice's testimony involves what is known in America as the "separation of powers."
Cabinet members must appear before Congress because their appointments are confirmed by the Senate. But a national security adviser is simply appointed by the president and not confirmed by Congress. And Bush, like other presidents before him, was at first reluctant to permit his appointee to testify without a fight.
Bush explained his change of heart yesterday to reporters at the White House.
"I've ordered this level of cooperation because I consider it necessary to gaining a complete picture of the months and years that preceded the murder of our fellow citizens on September 11, 2001," Bush said.
"Separation of powers" is a constitutional principal that seeks to ensure a balance of power in the United States, according to Alan Lichtman, a professor of history and political science at American University in Washington.
Lichtman tells RFE/RL that the framers of the U.S. Constitution -- who are commonly referred to as the "founding fathers" -- decided to divide the powers of the federal government into three parts to keep any one part of government from becoming too powerful.
There is an executive branch, in which the president can approve or veto legislation, and has the command of the armed forces. There is the legislative branch, which passes laws and can try to override presidential vetoes, and has the authority to impeach the president. And there is the judiciary, which has the power to review the validity of laws passed by Congress and executive actions taken by the president.
"It was the view of the founding fathers that there was a real danger in a republic that some faction would gain control of the government and oppress the people of the United States. One mechanism [to prevent this] was to separate powers among three branches of government. By spreading out the power in this way, the founding fathers sought to guard against tyranny in America," Lichtman said.
The Bush administration initially resisted the idea of the 11 September commission -- a 10-member panel equally divided between Democrats and Republicans -- but eventually agreed to it because of public pressure. Lichtman says the White House's reluctance to have such an investigation is understandable, given the scrutiny it would face. The administration of President Franklin Roosevelt was scrutinized by a similar commission after the Japanese attack on Pearl Harbor in 1941.
But Lichtman says Bush probably should not be concerned about the findings of the commission.
"The history of these prestigious, bipartisan commissions has been such that they're not usually inclined to go after the current administration. They're bipartisan, there has to be compromise, they're filled with establishment figures, and generally they have not been damaging to a sitting president," Lichtman said.