The nuns say they were exercising their right to free speech when they cut through a fence around a Minuteman III missile silo, used their own blood to paint a cross on the military structure and began swinging at it with hammers.
Prosecutors say those actions interfered with national defense -- a crime that could put the women behind bars for 20 years.
Dominican sisters Ardeth Platte, 66, Carol Gilbert, 55, and Jackie Hudson, 68, head to court today for a trial supporters say is ill-timed because of the war in Iraq.
"If it had been Iraq and these nuns had found these weapons, everyone would have praised them as heroes. And that's exactly the right response," said Anabel Dwyer, a legal advisor to Platte.
The nuns, jailed since their Oct. 6 protest near Greeley, Colo., maintain they were a "citizen weapons inspections team" that was symbolically disarming the U.S.
They had argued that their actions fell under principles established by the war crimes tribunal at Nuremberg, Germany, after World War II. The United States endorsed the principle that people are obligated to disobey laws that lead to crimes against humanity. But U.S. District Judge Robert Blackburn ruled the defense may not be used at the trial.
The women will now argue they were exercising symbolic free speech, according to Walter Gerash, who represents Hudson. Each faces one count of willful injury, interference or obstruction of national defense.