Updated

The first civilian convicted by a military court in more than 40 years is arguing that the Constitution forbids military justice for civilians.

A lawyer for former Army translator Alaa "Alex" Mohammad Ali told an Army appeals court Wednesday that upholding Ali's conviction would be a "slippery slope" that would lead to increased use of military courts for civilians.

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.

The case is the first under a 2006 law making it easier to bring criminal charges against civilians working for the U.S. military. Defendants have fewer rights in military than in U.S. civilian courts.

The 2006 provision was intended to close a legal loophole that made military prosecution of civilians very difficult without a formal declaration of war by Congress. The fighting in Afghanistan and Iraq has occurred without a congressional war declaration.

In a series of rulings dating back to the 1950s, the Supreme Court has greatly narrowed the use of courts-martial for civilians.

Army Capt. Tiffany Dewell, Ali's lawyer, said Congress overstepped its authority when it changed the law in 2006 and left open the possibility that almost anyone accompanying U.S. forces in combat could be tried by a court-martial for crimes committed in the field. Dewell said reporters embedded with military units potentially could be affected.

Defense Department regulations put in place after the law took effect prohibit military trials for U.S. citizens. But the presiding judge at Wednesday's hearing, Col. Kenneth Tozzi, wondered if an American civilian serving as a cook could be tried by a court-martial if he were accused of murder.

Maj. Adam Kazin, representing the government, acknowledged that the law allows such trials for American civilians. Courts-martial lack some constitutional protections, including the right to a jury of one's peers.

Since 2000, a separate federal law has allowed for the prosecution in U.S. civilian courts of military contractors. But the law excludes people like Ali who are citizens of the country in which the alleged crime takes place.

So he would have escaped American justice altogether without the court-martial, a point raised by Tozzi and the other two judges on the panel.

In addition, Ali was attached to a unit of military police who were training their Iraqi counterparts. While Ali was not a U.S. soldier, he "wore the uniform of our country," Kazin said. "It even said U.S. Army on it."

Tozzi gave no timetable for a ruling.