Attorneys for Staff Sergeant Robert Bales say they’re unsure if they’ll pursue a mental health defense in the case.
But if they do, the judge has ordered that the soldier must undergo a so-called sanity board review.
Bales is accused of murdering 16 Afghan civilians and wounding six others in an overnight rampage last March.
He could be executed if found guilty.
Bales deferred to enter a plea at an arraignment hearing Thursday held at Joint Base Lewis-McChord.
His attorneys have suggested that the soldier, who was on his fourth deployment during the alleged murders, suffers from post-traumatic stress disorder and traumatic brain injury.
The sanity review is conducted by a panel of psychiatrists or psychologists, often with specialized training in forensic psychiatry or psychology.
So far, Bales' attorneys have refused to let him take part in the review because the Army would not allow defense to be present or appoint an expert in traumatic brain injuries to the panel. The panels are supposed to be neutral, but outside the courtroom, Bales's attorney John Henry Brown said he was skeptical. He told reporters, "Keep in mind these doctors are not independent doctors, these are doctors that work for the Army, and the Army is trying to kill my client, so we have some concerns about that."
The defense also expressed concern to judge Colonel Jeffery Nance about what kind of information from that review would be provided to the prosecution and when. They argued that it could violate Bales' right against self-incrimination under the Fifth Amendment of the Constitution.
The judge didn’t immediately rule on the conditions of the sanity review or when prosecutors can have access to the results.
Army prosecutors called for a June 10, 2013, trial date because of concerns over access to Afghan witnesses. Bales' team called that unrealistic given the volume of documents and discovery they need to review.