The Army accuses him of betraying his fellow soldiers.
At a court martial that began Monday at Fort Lewis, south of Seattle, the 28-year-old faces four years in prison if convicted on one count of missing movement and two counts of conduct unbecoming an officer for refusing to ship out with his unit, the 3rd Brigade, 2nd Infantry Division.
Watada, who joined the military in March 2003, has spoken out against U.S. military involvement in Iraq, calling it morally wrong and a breach of American law.
"As the order to take part in an illegal act is ultimately unlawful as well, I must as an officer of honor and integrity refuse that order," Watada said in a video statement released at a June 7 news conference.
Despite having already been charged, he spoke out again in August, at a Veterans for Peace rally in Seattle.
"Though the American soldier wants to do right, the illegitimacy of the occupation itself, the policies of this administration, and the rules of engagement of desperate field commanders will ultimately force them to be party to war crime," Watada said then.
Watada and his Honolulu attorney, Eric Seitz, contend his comments are protected speech, but Army prosecutors argued his behavior was dangerous to the mission and morale of other soldiers.
"He betrayed his fellow soldiers who are now serving in Iraq," Capt. Dan Kuecker said at one hearing. Kuecker has not commented on the case outside of court.
Seitz unsuccessfully sought an opportunity to argue the legality of the war, saying it violated Army regulations that specify wars are to be waged in accordance with the United Nations charter. His final attempt was quashed last month when the military judge, Lt. Col. John Head, ruled Watada cannot base his defense on the war's legality. Head also rejected claims that Watada's statements were protected by the First Amendment.
The Army had subpoenaed two journalists who interviewed Watada, drawing criticism from free-press advocates, but that fell by the wayside as prosecutors dropped two of the four counts of misconduct in exchange for Watada admitting he made statements to freelance journalist Sarah Olson and Greg Kakesako of the Honolulu Star-Bulletin.
Military law experts said that, by confining themselves to the missing movement charge, prosecutors might have saved themselves from arguing some of the legal issues relating to free speech.
"It's desirable that they're abandoning the path of using reporters as witnesses," said Eugene Fidell, president of the National Institute of Military Justice in Washington, D.C. "It's a very toxic strategy."
Fidell wasn't surprised the government rejected a deal offered by Seitz that would have had Watada serve only three months confinement with a dishonorable discharge.
"Why should they? He missed a movement of his unit," he said. "No army can tolerate officers refusing to move with their unit."