In the United States, the lead up to war with Iraq included robust efforts to convince the United Nations Security Council and Member States that Saddam Hussein still possessed weapons of mass destruction and was therefore in violation of United Nations Security Resolution 687, passed on April 3, 1991 after the Gulf War. Security Council Resolution 687 required Iraq to destroy its nuclear, chemical and biological weapons or weapons programs and to refrain from developing others.¹ United Nations Security Resolution 1441, adopted 8 November 2002 recognized the threat Iraq’s non-compliance with Council resolutions and proliferation of weapons of mass destruction and long-range missiles poses to international peace and security and called for sites to continue to be assessed and for Iraq to comply with requests to reveal and hand over any weapons of mass destruction still in their possession. This would form the foundation of the 'case for war' made by the Bush administration. They maintained that Hussein was not compliant with these Security Council Resolutions and given his breach of such obligations, was subject to the provision that allowed for serious countermeasures.

The Security Council, and only the Security Council, is vested with the power to decide the appropriate actions in the event of non-compliance with Security Council Resolutions. The case for war was presented to the Council and it failed to receive support for collective action. Therefore, when the U.S. decided to pursue the invasion without such approval and also failing to meet any other conditions such as self-defense, it was in effect breaching its obligations under international law. This paper aims to define the obligations of states under international law to explain why the U.S. invasion of Iraq in 2003 was a breach of those laws. It further aims to take the case of Iraq as a study for how the failure of the United Nations to prevent such a breach and to hold the aggressor responsible when a breach occurs jeopardizes the legitimacy of the United Nations system.