Like many patriotic Americans Lt. Ehren Watada enlisted after September 11, desiring to serve his country and fight our enemies. Like many patriotic Americans Lt. Watada was betrayed by an administration that was never interested in fighting our real enemies, but rather in pursuing its own aggressive war of choice. He is currently refusing to serve in Iraq because it is an illegal war. He had a hearing on August 17, which resulted in a recommendation for court martial. At the hearing he had an impressive group of defense witnesses:

Approximately three hours of the four-hour hearing were devoted to testimony by former United Nations Undersecretary Denis Halliday, Army Colonel Ann Wright (ret.), who resigned in March 2003 to protest the invasion of Iraq, and University of Illinois Professor Francis Boyle, an international law expert.

The defense submitted documents into evidence including an amicus brief filled by the American Civil Liberties Union, the Charter of the United Nations, The War Crimes Act, a German high court ruling in favor of a soldier who refused to participate in the Iraq war, and letters of support from organizations and prominent individuals, including Representative Neil Abercrombie of Hawaii.

There is an interview with Lt. Watada here, in which he says:

Despite conflicting loyalties, I am fighting for the allegiance to which I swore an oath to uphold and defend — the Constitutional laws and principles of democracy. My decision brings honor to veteran JAs (Japanese Americans.) Instead of perpetuating war crimes and a war of aggression, I am actively trying to put a stop to it. Instead of being the “quiet, obedient Japanese,” I am fulfilling my oath to protect my soldiers and this country from our government. This is all at great expense — when the easier, safer path would have been to do my tour in Iraq.
. . .
When I volunteered after 9/11 to serve my country I knew I would have to follow orders — sometimes without rhyme or reason. I would have to be obedient and respectful to authority. Never did I believe I would have to follow orders that were contrary to my moral beliefs and illegal. Moreover, never could I have conceived that my trust in leadership would be shattered because of their deception used to wage this war.
. . .
I knew joining the Army, whether it was fighting in a foreign war or now fighting for the rights of soldiers, meant sacrifice. In combat, you may lose a limb, bodily functions, or your life. Speaking out against an authoritarian government and refusing to obey their unlawful orders may mean loss of liberty and other less than pleasant things. These are both sacrifices and commitments made to the American people as an American soldier. I gave my life to protect freedom and democracy — a sacrifice I am willing to make by doing the right thing.

In a way I’m already free. Physically they can lock me up, throw away the key, leave me to rot and contemplate my “crimes.” For a long time I was in turmoil. I felt compelled to fulfill the terms of my contract despite what I knew to be utterly wrong. Only when I realized that I served not men and institutions but the people of this country, did I believe there was another answer. That choice was to do what is right and just.

Supporters of Lt. Watada have a page with information and opportunities to support his stand here.