From the Four Reasons (to Impeach) website:
1. The invasion of Iraq has been planned for many years by the Project for the New American Century (PNAC), an organization founded by a small group of right wing political ideologues and corporate elite dedicated to promoting American global leadership. The PNAC signatories hold the most powerful positions in the current administration and other highly influential political offices. Read their Statement of Principles and note the signatories. Read the PNAC's "Rebuilding America's Defenses" for a detail of their military strategy for American global hegemony. The Downing Street Memo and other key documents unambiguously indicate that the policy of regime change in Iraq was planned as early as July 2002 and "the intelligence and facts were being fixed around the policy."
2. Many members of the Bush Administration are convicted criminals. The World Tribunal on Iraq held it's culminating session in Istanbul in June 2005 and declared the Bush Administration guilty of starting a War of Aggression, War Crimes and Crimes against Humanity as indicated in their Declaration of the Jury of Conscience. A War Crimes Tribunal held in NYC on August 26, 2004 found many members of the Bush Administration guilty of war crimes, crimes against humanity, and high crimes and misdemeanors for which they are impeachable (audio of Ramsey Clark). The International Criminal Tribunal for Afghanistan convened in Tokyo, 2003 found the Bush Administration guilty of war crimes and crimes against humanity for the invasion of Afghanistan. The Brussels Tribunal has conducted "A Hearing on the Project for the New American Century" to discuss the nature of a premeditated, preemptive wars - a "war of aggression" being the highest international crime. In 1992, an International War Crimes Tribunal found the senior officers in the first Bush administration guilty on 19 counts of Crimes Against Peace, War Crimes, Crimes Against Humanity and other criminal acts in Violation of the Charter of the United Nations, International Law, The Constitution of the United States and Laws made in Pursuance thereof, for crimes committed during "Operation Desert Storm". View a list of our `elected' officials, their appointees, and their criminal offenses.
3. There is no degree of separation between the current administration and those who control the means of production, the means of communication, and the military-industrial complex. Those individuals will benefit unfathomably from this and many future wars already planned by the PNAC. View information on who is making the money from the "War on Terrorism".
4. "We the People" pay for "Operation Iraqi Freedom", the staging of "multiple theatre wars", and the killing of the innocent peoples of foreign lands in the name of Freedom and Democracy, while 'elected' officials pass radical legislation taking away our rights and controlling the flow of information.