Of all the international criticisms of the war that broke out Thursday in Iraq, none cut more deeply into America's image of itself than the argument that the US-led attack is illegal.
International-law experts are divided on whether Washington has the right to invade Iraq in the absence of a UN Security Council resolution specifically authorizing such an assault.
But most agree that President Bush cannot justify the war with his new doctrine of preemptive military action to forestall the threat that he says Saddam Hussein poses. Preemptive force "is extremely dangerous and flat-out illegal," says Jordan Paust, professor of international law at the University of Houston. "Implying a right to take out a regime that threatens us - that is quite threatening to the international legal order."
French President Jacques Chirac said Tuesday he had opposed the war "in the name of the primacy of the law," and slammed the US administration for preferring "the use of force over compliance with the law." UN Secretary-General Kofi Annan also warned last week that war on Iraq without a new resolution endorsing it "will not be in conformity with the (UN) Charter," a cornerstone of international law.
But British Foreign Minister Jack Straw insisted yesterday that "every single thing we are doing is in compliance with (UN Security Council) Resolution 1441," which last November threatened President Hussein with "serious consequences" if he did not take a last chance to give up his weapons of mass destruction. "We are putting that resolution into effect, not avoiding it," he added.
White House counsel Alberto Gonzales and British legal authorities have concluded that UN Security Council Resolution 1441 is all the legal authority Washington needs for the war.
France and Russia have since said they did not intend the threat of "serious consequences" to mean armed force without a second resolution. When the Security Council has threatened war in the past, it has always talked of "all necessary means" as a hallowed euphemism.
Washington and London, however, argue that Resolution 1441 harked back in its preamble to Resolution 678, passed in 1990, authorizing the use of force to expel Iraqi troops from Kuwait "and to restore international peace and security in the area." That authority, British Attorney General Lord Goldsmith told Parliament this week, has been revived by Iraq's failure to observe the terms of the Gulf War ceasefire, which included a pledge to hand over all chemical, biological, and nuclear weapons within 90 days.
That reasoning is questionable, argued opposition Liberal Democratic legal affairs spokesman Lord Goodhart on BBC radio. Resolution 687, which ended the last Gulf War, "specifically authorized the use of sanctions (but) I certainly don't believe that authorizes armed intervention without a second resolution," he said.
At a more fundamental level, however, critics charge that the war breaches Article 51 of the UN Charter, which asserts "the inherent right of individual or collective self defense if an armed attack occurs against a member of the United Nations." Otherwise the use of force requires UN Security Council approval.
Iraq has not attacked the US, and "I don't think America is coming under armed attack from Iraq," Arab League Secretary-General Amr Moussa said Wednesday. "I don't think anyone could say that the armed action they (the Americans) are going to take is within the frame of the UN Charter."
President Bush seemed to stretch the interpretation of Article 51 in his speech to the nation Monday, saying that the US "has the sovereign authority to use force in assuring its own national security. "Terrorists and terror states do not reveal these threats with fair notice, in formal declarations; and responding to such enemies only after they have struck first is not self-defense, it is suicide," the president added.
International law, and the way the UN Charter is interpreted, has evolved over the years. The 1999 intervention in Kosovo, for example, was seen as legitimate by Western powers - though it had no Security Council backing - because it was cast as a humanitarian intervention.
Interpreting Article 51 to suit a changed world, argues Martti Koskenniemi, an international-law professor at the University of Helsinki, Washington could justify a preemptive strike "if it is shown that the Iraqi leadership ... is in possession of some sort of weapon, plus a means to get it to the United States, plus actually imminently intending to do that. But otherwise not."
Though US officials have argued that Hussein has ties to terrorist organizations that he might supply with weapons of mass destruction, Secretary of State Colin Powell's attempts to convince his UN colleagues of this last month were greeted with widespread skepticism.
The war could be legitimized - even though it is illegal - "if we find all the things that we say we are going to find" such as chemical and biological weapons, argues Anne Marie Slaughter, dean of the Woodrow Wilson School of Public and International affairs at Princeton University. "But it is going to require that the US and Britain truly prove their case," she adds.
At the same time, she says, the past six months of diplomatic wrangling over Iraq show paradoxically that "the regime [of international law] regarding the use of force has never been stronger than it is right now." Though Britain and the US eventually dropped their effort to get a second resolution passed, the fact that they tried so hard, and that Mr. Bush justified military action in terms of earlier UN resolutions when he spoke to the American people on Monday, show that the Security Council has become more than the talking shop of the cold war years, Professor Slaughter says. "Even now, all sides are focusing on the UN. We've made it pretty clear that the UN is indispensable [to] what happens in the future in Iraq."
• Seth Stern in Boston contributed to this report.