In an open letter to President Bush, Wilton D. Gregory the President of the United States Council of Catholic Bishops stated that they, as well as the Holy See, were deeply troubled by the precedents involved with what they perceived to be the "unilateral" use of force in Iraq without international sanction by the United Nations. The Holy See (John Paul II) contended that without broad consensus and approval by the United Nations security council the use of force in Iraq lacks legitimate authorization. Dr. Jean Elshtain, an expert in the just war tradition, amongst many other Natural Law scholars disagrees.
Dr. Elshtain contends there is nothing prescribed by the Just War tradition that mandates a group of states in concert must agree upon taking military action. At the onset of military action there was broad consensus amongst the American public and support for the miltary action was overwhelmingly approved by the United States Congress and the imperatives of the United States Constitution. Each criteria for the determination of a justified war assumes that the state, in this case the United States, is the decision making entity. Dr. Eshtain argues- and I think successfully- that the concept that the United Nations is the only legitimate decision making body violates the principles of both international law and the UN Charter itself. Both assume state sovereignty and subsequently the right to self defense. With that right is the right to determine what the parameters of that defense shall be. I would add further that the international body itself lacks legitimate authority, that it is itself a poisoned body, one that is incapable of determining the moral parameters of just war.
The Security Council includes France and Russia both who have been determied to be acting upon self interest, seeking to protect their lucrative arms contracts and in other cases nefarious and illegal oil-for-food profits illegally skimmed off programs intended to feed the poor citizens of Iraq. Certain members of the United Nations themselves lack legitimate authority having assumed power not at the will of the people whom they rule but at the edge of a sword. Despotic nations states lack the legitimate authority to prescribe a moral defense for the United States when their motivation is empircally suspect and predicated upon a protection of their own power.
Furthermore, this war was a continuation of Gulf War I which was authorized by the United Nations. Iraq had continually violated the sanctions placed upon it by the 1991 cease fire agreement. Saddam had ignored 17 separate United Nations resolutions, had repeatedly attacked United States aircraft, and kicked out weapons inspectors in 1998. In violating the requirements of the ceasefire of 1991 and the subsequent 17 resolutions demading Iraq do so the determination to use force had already been legitimated.