FORT LEWIS, Wash — A judge declared a mistrial Wednesday in the court-martial of an Army lieutenant who refused to deploy to Iraq, saying the soldier did not fully understand a document he signed in which he admitted to elements of the charges.

Prosecutors said 1st Lt. Ehren Watada admitted in the document that he had a duty to go to Iraq with his fellow soldiers.

But Watada, under questioning with the military jury absent, said he had intended to admit only that he had not gone to Iraq, not that he was duty-bound to deploy to Iraq with his unit.

Military judge Lt. Col. John Head set a March 19 date for a new trial and dismissed the jurors. Watada’s lawyer objected to the mistrial and said a second one would amount to double jeopardy — more than one prosecution for the same alleged crime.

Watada, 28, of Honolulu, had been expected to testify in his own defense Wednesday.

He is the first commissioned officer to be court-martialed for refusing to go to Iraq, said Eugene Fidell, president of the National Institute of Military Justice in Washington, D.C.

In the 12-page stipulation of fact he signed last month, Watada acknowledged that he refused to deploy last June with the 3rd Brigade, 2nd Infantry Division, and that he made public statements criticizing the Iraq war. Watada has said he refused to go to Iraq because he believes the war is illegal.