Fort Hood released the decision late Tuesday from the Army Court of Criminal Appeals.
Maj. Nidal Hasan says he grew a beard because his Muslim faith requires it, despite the Army's ban on beards.
He is appealing the trial judge's order that he be forcibly shaved, which his attorneys say violates his right to practice his religion without substantial government intrusion.
The appeals court, which is on Fort Belvoir in northern Virginia, will hear from prosecutors and defense attorneys Oct. 11.
Hasan faces the death penalty if convicted in the 2009 shootings that killed 13 people at the Texas post.