The invasion phase began on 19 March 2003 (air) and 20 March 2003 (ground) and lasted just over one month, including 26 days of major combat operations, in which a combined force of troops from the United States, the United Kingdom, Australia, and Poland invaded Iraq.

As evidence supporting U.S. and British charges about Iraqi Weapons of mass destruction and links to terrorism weakened, some supporters of the invasion have increasingly shifted their justification to the human rights violations of the Saddam government.

Leading human rights groups such as Human Rights Watch have argued, however, that they believe human rights concerns were never a central justification for the invasion, nor do they believe that military intervention was justifiable on humanitarian grounds, most significantly because "the killing in Iraq at the time was not of the exceptional nature that would justify such intervention."

“The successive US Administrations are committing war crimes and other serious violations of international law in Iraq as a matter of routine policy,” said the Office of the United Nations High Commissioner for Human Rights (OHCHR).

“Beyond the now-infamous examples of torture, rape, and murder at Abu Ghraib prison, the United States has ignored international law governing military occupation and violated the full range of Iraqis’ national and human rights—economic, social, civil, and political rights. The systematic nature of these violations provides compelling evidence of a policy that is rotten at its core and requires fundamental change. The occupation of Iraq is not leading to greater respect for rights and democracy, as promised by the Bush Administration, but rather entrenching a climate of lawlessness and feeding an increasing spiral of violent conflict that will not end until the occupation ends and underlying issues of justice are addressed,” (OHCHR) added.

Human Rights Watch underlined that “in the lead up to the US-led invasion of Iraq on March 20, 2003, proponents of the war spoke of the Iraqi people as helpless victims of a dictatorial regime. Yet the Iraqi people paid the heaviest price of the invasion. Almost half a million people lost their lives, millions lost homes, and countless civilians suffered abuses by all parties to the conflict.” (ILKHA)