A press statement released by the Texas installation said trial judge Col. Gregory Gross issued the order on Thursday.
Hasan, a Muslim, has grown a significant beard while in jail awaiting trial and his defense counsel argued that forcing him to shave would "leave him in a perilous religious state" and would violate the Religious Freedom Restoration Act. They added that Hasan had "sincere and genuine religious motives for growing a beard which were further strengthened this year."
The judge ruled that the act does apply to courts martial proceedings but Hasan's defense team had failed to meet their burden to prove that the beard should be allowed.
The defense is expected to appeal the ruling, the Fort Hood statement indicated, to the Army Court of Criminal Appeals