Three Army judges are weighing a question that hasn't cropped up in decades: whether a civilian contractor working for the U.S. military can be tried in a military court. The issue eventually could end up at the Supreme Court.

The case of Alaa "Alex" Mohammad Ali, a former Army translator in Iraq, challenges the notion that courts-martial only have authority over members of the armed forces. But it also runs up against complaints that using U.S. civilian courts to prosecute contractors working with U.S. forces in Afghanistan and Iraq has been largely ineffective, and trying them in local courts often has not been possible.

Ali, an Iraqi-Canadian, was prosecuted by the military after an altercation in Iraq during which he allegedly stole a U.S. soldier's knife and used it to stab another translator. He pleaded guilty to lesser charges.

Ali's appeal is before the Army Court of Criminal Appeals. He was convicted under rules issued after Congress amended the Uniform Code of Military Justice in 2006 to allow courts-martial of civilians in Iraq and Afghanistan.

At a hearing Wednesday, the three Army colonels serving as judges wondered how far the military's authority could extend when civilians are involved. "Does citizenship matter?" Col. Theresa Gallagher asked.

Maj. Adam Kazin, representing the Army, said the rules would apply equally to Americans and foreigners.

Capt. Tiffany Dewell, Ali's lawyer, said that almost anyone accompanying troops in the field, including embedded reporters and Red Cross workers, potentially could be affected. The new rules have not been applied to U.S. citizens.

Could a contractor be hauled before a court-martial "if he didn't show up for work?" Col. Kenneth Tozzi, the presiding judge, asked.

In some circumstances, Kazin said.

Until recently, such an exchange was inconceivable, said Geoffrey Corn, a professor at the South Texas College of Law in Houston. Corn said that when he was an instructor for Army lawyers in the late 1990s, he told his students he could not "imagine the day when a civilian would be court martialed again."

At one time, the military asserted broad power to prosecute people accused of wrongdoing who were not part of the armed forces themselves, but were accompanying soldiers or working with them.

Soldiers' wives, and even ex-servicemen who had returned to civilian life, were held accountable in military courts until Supreme Court decisions in the 1950s said otherwise.

By 1970, even the top military appeals court agreed that civilians could not be brought to justice in a military court. The only exception would be when Congress has formally declared war on another country, something that hasn't happened since World War II.

U.S. civilian courts give defendants more rights, including trial by a jury of one's peers. The life-tenured judges who preside over federal trials have more independence than the military officers who serve as judges in courts-martial.

But U.S. intervention in Afghanistan and Iraq brought with it a huge increase in the number of private contractors accompanying U.S. forces.

In 2006, amid complaints that contractors were beyond the reach of U.S. law, Sen. Lindsey Graham, R-S.C., inserted a change in the rules to allow for civilian prosecutions in military courts in Afghanistan, Iraq and other "contingency operations" where there was no formal declaration of war.

At the time, Graham said the change would "give military commanders a more fair and efficient means of discipline on the battlefield" and hold civilian contractors accountable.

There was no debate on the provision, which took even lawyers for the military by surprise, said Victor Hansen, a former Army lawyer who teaches at New England Law in Boston.

But the measure seemed to be trying to deal with the problems that resulted from contracting with private companies to perform a lot of work that used to be done by the military itself, Hansen said. "How do you have accountability over them?" he asked.

A law passed in 2000, the Military Extraterritorial Jurisdiction Act, was intended to allow for civilian prosecution of contractors and civilian Defense Department workers accused of serious crimes overseas. But it was only infrequently used. More recent changes have improved its effectiveness, Assistant Attorney General Lanny Breuer recently told Congress.

That law still applies only to people attached to the Defense Department, and the Obama administration is asking congress to extend it to other government employees and contractors.

Ali's situation is unusual in that both Dewell and Kazin said he could not have been prosecuted under the 2000 law because it does not apply to people who are citizens of the country where their alleged crimes took place.

He also worked directly with U.S. troops, a unit of military police officers, at a combat outpost in western Iraq.

Eugene Fidell, president of the National Institute of Military Justice, said he is not surprised that Ali turned out to be the first case to go forward "rather than the civilian employee or embedded journalist."

Ali's case is a good one for the government, Fidell said, because he probably would not otherwise have been punished.