Retired warrant officer Paul Ravensdale faces six charges, including manslaughter, in the death of Cpl. Josh Baker in Afghanistan three years ago.
Four other soldiers were injured when an anti-personnel mine misfired and sent hundreds of steel ball bearings flying the wrong way.
The military judge presiding over the case told panel members they must only consider the evidence presented at the court martial.
He says they must ignore reports in the media and comments on social media sites.
Ravensdale was leading the exercise on a weapons range near Kandahar city when the accident occurred.
The prosecution alleges he ignored safety rules and allowed soldiers to stand too close to the anti-personnel mines without protection.
But his defence lawyer has said Ravensdale was simply following plans approved by his superiors.
Two of those superiors have already been convicted in the case.
Maj. Christopher Lunney was demoted to captain and given a severe reprimand after pleading guilty to negligent performance of duty.
Maj. Darryl Watts is awaiting sentencing on negligence and unlawfully causing bodily harm.Suggest a correction