Is it legal for the United States to invade Iraq?
Many experts in international law question the legal basis for war, since the United Nations did not authorize the use of force to oust Saddam Hussein, either in 1990 or last fall.
But other legal scholars say they agree with U.S. and British authorities that Hussein's failure to fully comply with the agreements that ended the 1991 Persian Gulf War justifies a new war to remove him from power.
The arguments turn on what was said -- and not said -- by the U.N. Security Council, then or now.
After Hussein's invasion of Kuwait in 1990, the U.N. authorized the use of "all necessary means" to drive out the Iraqis and restore Kuwait's "independence and territorial integrity."
In April 1991, after a U.S.-led coalition liberated Kuwait, the United Nations adopted Resolution 687, which required Iraq to "unconditionally accept the destruction, removal or rendering harmless under international supervision of all chemical and biological weapons."
U.S. and European officials agree that Iraq has not fully complied. Last November, a frustrated Security Council unanimously adopted a new resolution that deplored Iraq's "failure to cooperate" with inspectors and to give a "full, final and complete disclosure" of its secret weapons.
Resolution 1441 pledged to "ensure full and immediate compliance" with the "disarmament obligations" set in 1991.
To get there, the resolution set nine "binding" steps that dealt with giving inspectors "the right to free, unrestricted access" to sites where weapons might be hidden. It ended by warning Iraq that it would face "serious consequences" if it violated those obligations.
On Monday, U.S. and British officials cited these past resolutions as authorizing war, even though the Security Council refused to take that step.
Lord Goldsmith, the British attorney general, told Parliament that the "combined effect" of the resolutions meant "military action against Iraq was legal without a second resolution."
"The authority to use force [in 1990 and 1991] has revived and so continues today," he asserted, since Iraq has not fully complied with its obligations.
Secretary of State Colin L. Powell took the same view Monday, saying Iraq's "flagrant violations of obligations that it entered into over the last 12 years" justify a war to remove Hussein.
Many legal experts dispute that analysis, since the U.N. did not authorize force to overthrow Hussein in 1990 and has not declared him in violation of the new inspections this year.
"I think most international lawyers would say the use of force against Iraq is clearly unlawful without a second resolution," said American University law professor Robert K. Goldman. "The original resolution [in 1990] never authorized military action to remove Saddam. Bush's father [President George H.W. Bush] spoke quite clearly on that and said going to Baghdad would exceed the U.N. mandate."
Tufts University law professor Michael J. Glennon agreed, saying that "this is the easiest argument to dismiss. The Security Council did not authorize the use of force against Iraq beyond removing it from Kuwait."
The recent Resolution 1441 is not clear one way or the other, Glennon added.
"That's the only legal leg they have to stand on," he said. "The resolution is vague, and it can be interpreted in different ways."
The U.S. and British officials have stressed that the November resolution speaks of Iraq's being in "material breach" of its duties. This implies that Iraqis had a duty to come clean or face "serious consequences."
But the French, Germans and other foes of a war say the resolution set up a process for inspections and disarmament, not a trigger for military action.
Had the Iraqis blocked the inspectors, "that would have given the U.S. the trigger" to undertake war without a follow-up resolution, said Duke University law professor Scott Silliman. Though chief weapons inspector Hans Blix criticized the Iraqis, he did not pronounce them in material breach of the resolution, Silliman said.
"The whole key to which side you come down on on this issue is who becomes the arbiter of what is a material breach of 1441 and who has the authority to use force," said Silliman, a former Air Force attorney. It "takes us out on thin ice" to say the U.S. or Britain can decide unilaterally who is in violation of U.N. mandates, he said.
But supporters of the Bush administration say the U.N. resolutions set out the demands that Iraq had to meet, and thus justify a military response for its failure to comply.
"Resolution 687 [calling for Iraq to rid itself of chemical and biological weapons] gives you plenty of legal authority to go into Iraq," said Yale University law professor Ruth Wedgwood.
She also said the U.S. had never taken the rigid view that it could not take military action without the approval of the Security Council. In 1999, the U.S. undertook a bombing campaign in Yugoslavia's Kosovo province with NATO, but not U.N., approval, she said.
President Bush largely sidestepped the debate over the U.N. and international law Monday and said the U.S. "has the sovereign authority to use force in assuring its own national security."
As commander in chief and with the support of Congress, Bush said, he had all the authority he needed to order an invasion of Iraq.
"This is not a question of authority. It is a question of will," he said.
But Bush also repeated the legal claim that the U.N. resolutions adopted in 1990 and 1991 are "still in effect" and authorize the United States and its allies "to use force in ridding Iraq of weapons of mass destruction."
U.N. Secretary-General Kofi Annan said Monday that an attack without a further resolution would violate the U.N. Charter.
"If the action is to take place without the support of the council, its legitimacy will be questioned and the support for it will be diminished," he said.
Silliman said it is quite possible that France or another member of the council that opposes an invasion will criticize the U.S. at the U.N. in coming days for alleged violations of the charter. There could also be "a fraying of international relations because of the U.S. and Britain taking it on themselves of when force is used."
However, he said, an attempt to condemn the U.S. in a formal resolution is unlikely, because the U.S. or Britain could veto such a resolution.