Question: Why was Iraq in violation of U.N. Security Council Resolutions?
About the article "2003 invasion of Iraq", section "Legality of invasion".

Candidate passages:
  U.S. plan to invade Iraq: In a speech before the U.N. General Assembly, George W. Bush asserts that Iraq has defied various U.N. resolutions and is "a threat to the authority of the United Nations and a threat to peace".
He says that the US will work with the Security Council to draft the necessary resolutions for military action.  
The Authorization for Use of Military Force Against Iraq Resolution of 2002 was passed by congress with Republicans voting 98% in favor in the Senate, and 97% in favor in the House.
Democrats supported the joint resolution 58% and 39% in the Senate and House respectively.
The resolution asserts the authorization by the Constitution of the United States and the Congress for the President to fight anti-United States terrorism.
Citing the Iraq Liberation Act of 1998, the resolution reiterated that it should be the policy of the United States to remove the Saddam Hussein regime and promote a democratic replacement.
The resolution "supported" and "encouraged" diplomatic efforts by President George W. Bush to "strictly enforce through the U.N. Security Council all relevant Security Council resolutions regarding Iraq" and "obtain prompt and decisive action by the Security Council to ensure that Iraq abandons its strategy of delay, evasion, and noncompliance and promptly and strictly complies with all relevant Security Council resolutions regarding Iraq."
The resolution authorized President Bush to use the Armed Forces of the United States "as he determines to be necessary and appropriate" to "defend the national security of the United States against the continuing threat posed by Iraq; and enforce all relevant United Nations Security Council Resolutions regarding Iraq.
"The legality of the invasion of Iraq has been challenged since its inception on a number of fronts, and several prominent supporters of the invasion in all the invading nations have publicly and privately cast doubt on its legality.
It is argued that the invasion was fully legal because authorization was implied by the United Nations Security Council.
International legal experts, including the International Commission of Jurists, a group of 31 leading Canadian law professors, and the U.S.-based Lawyers Committee on Nuclear Policy, have denounced both of these rationales.
On Thursday 20 November 2003, an article published in the Guardian alleged that Richard Perle, a senior member of the administration's Defense Policy Board Advisory Committee, conceded that the invasion was illegal but still justified.
The United Nations Security Council has passed nearly 60 resolutions on Iraq and Kuwait since Iraq's invasion of Kuwait in 1990.
The most relevant to this issue is Resolution 678, passed on 29 November 1990.
It authorizes "member states co-operating with the Government of Kuwait... to use all necessary means" to (1) implement Security Council Resolution 660 and other resolutions calling for the end of Iraq's occupation of Kuwait and withdrawal of Iraqi forces from Kuwaiti territory and (2) "restore international peace and security in the area."
Resolution 678 has not been rescinded or nullified by succeeding resolutions and Iraq was not alleged after 1991 to invade Kuwait or to threaten do so.
Resolution 1441 was most prominent during the run up to the war and formed the main backdrop for Secretary of State Colin Powell's address to the Security Council one month before the invasion.
According to an independent commission of inquiry set up by the government of the Netherlands, UN resolution 1441 "cannot reasonably be interpreted (as the Dutch government did) as authorising individual member states to use military force to compel Iraq to comply with the Security Council's resolutions."
Accordingly, the Dutch commission concluded that the 2003 invasion violated international law.
At the same time, Bush Administration officials advanced a parallel legal argument using the earlier resolutions, which authorized force in response to Iraq's 1990 invasion of Kuwait.
Under this reasoning, by failing to disarm and submit to weapons inspections, Iraq was in violation of U.N. Security Council Resolutions 660 and 678, and the U.S. could legally compel Iraq's compliance through military means.
Critics and proponents of the legal rationale based on the U.N. resolutions argue that the legal right to determine how to enforce its resolutions lies with the Security Council alone, not with individual nations.
In February 2006, Luis Moreno Ocampo, the lead prosecutor for the International Criminal Court, reported that he had received 240 separate communications regarding the legality of the war, many of which concerned British participation in the invasion.
In a letter addressed to the complainants, Mr. Moreno Ocampo explained that he could only consider issues related to conduct during the war and not to its underlying legality as a possible crime of aggression because no provision had yet been adopted which "defines the crime and sets out the conditions under which the Court may exercise jurisdiction with respect to it."
In a March 2007 interview with the Sunday Telegraph, Moreno Ocampo encouraged Iraq to sign up with the court so that it could bring cases related to alleged war crimes.
United States Ohio Congressman Dennis Kucinich held a press conference on the evening of 24 April 2007, revealing US House Resolution 333 and the three articles of impeachment against Vice President Dick Cheney.
He charged Cheney with manipulating the evidence of Iraq's weapons program, deceiving the nation about Iraq's connection to al-Qaeda, and threatening aggression against Iran in violation of the United Nations Charter.
  U.N. Security Council Resolution 2087, condemning the North Korean satellite launch as a violation of a ban on North Korean ballistic missile tests, as the rocket technology is the same, is unanimously adopted.
The agreement broadened the sanctions included in previous resolutions.  
After Iraq was driven by U.S.-led coalition forces out of Kuwait during Operation Desert Storm, Iraq and the U.N. Security Council signed a ceasefire agreement on March 3, 1991.
Throughout the 1990s, the U.N. Security Council passed 16 Resolutions calling for Iraq to disarm the WMDs program unconditionally and immediately.
Because no peace treaty was signed after the Gulf War, the war still remained in effect, such as an assassination attempt of former U.S. President George H. W. Bush by Iraqi agents while on a visit to Kuwait and Iraq was bombed in June 1993 as a response, Iraqi forces firing on coalition aircraft patrolling the Iraqi no-fly zones, U.S. President Bill Clinton's bombing of Baghdad in 1998 during Operation Desert Fox, and an earlier 1996 bombing of Iraq by the U.S. during Operation Desert Strike.
The war remained in effect until 2003 when U.S. and United Kingdom forces invaded Iraq and toppled Saddam Hussein's regime from power. 
Debate about the legality of the 2003 invasion of Iraq under international law, centers around ambiguous language in parts of U.N.
Resolution 1441 (2002).
The U.N. Charter in Article 39 states: "The Security Council shall determine the existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or decide what measures shall be taken in accordance with Articles 41 and 42, to maintain or restore international peace and security".
The position of the U.S. and U.K. is that the invasion was authorized by a series of U.N. resolutions dating back to 1990 and that since the U.N. security council has made no Article 39 finding of illegality that no illegality exists.
Resolution 1441 declared that Iraq was in "material breach" of the cease-fire under U.N.
Resolution 687 (1991), which required cooperation with weapons inspectors.
The Vienna Convention on the Law of Treaties states that under certain conditions, a party may invoke a "material breach" to suspend a multilateral treaty.
Thus, the U.S. and U.K. claim that they used their right to suspend the cease-fire in Resolution 687 and to continue hostilities against Iraq under the authority of U.N.
Resolution 678 (1990), which originally authorized the use of force after Iraq invaded Kuwait.
This is the same argument that was used for Operation Desert Fox in 1998.
They also contend that, while Resolution 1441 required the UNSC to assemble and assess reports from the weapons inspectors, it was not necessary for the UNSC to reach an agreement on the course of action.
If, at that time, it was determined that Iraq breached Resolution 1441, the resolution did not "constrain any member state from acting to defend itself against the threat posed by Iraq".
It remains unclear whether any party other than the Security Council can make the determination that Iraq breached Resolution 1441, as U.N. members commented that it is not up to one member state to interpret and enforce U.N. resolutions for the entire council.
In addition, other nations have stated that a second resolution was required to initiate hostilities.
Some have asserted that the war was an illegal war of aggression, and Kofi Annan, former United Nations Secretary-General, expressed the belief that the war in Iraq was an "illegal act that contravened the U.N.
charter."