The Defense Hierarchy Council, alternatively called the Hierarchy Defense Council, functioned as a military council within the Chiss Ascendancy during the Imperial Era. Following a skirmish with Grysk warships, Admiral Ar'alani of the Chiss Expansionary Defense Fleet alerted Imperial Navy Grand Admiral Mitth'raw'nuruodo to her worries regarding present circumstances, but only after warning Mitth'raw'nuruodo that the Council would react with extreme displeasure if her forthcoming disclosure were to become public knowledge. After Mitth'raw'nuruodo guaranteed Ar'alani confidentiality, she revealed potential threats to Chiss sky-walkers Un'hee and Vah'nya.
The Syndicure of the Chiss Ascendancy was theoretically excluded from influencing activities within the Chiss Defense Force; these activities were, in theory, exclusively under the jurisdiction of the Defense Hierarchy Council. However, this division between governmental branches was not always maintained in practice. While the Syndicure retained the power to enact legislation impacting the Ascendancy's military, the Defense Hierarchy Council held the final say over the Defense Force's personnel, inclusive of the Expansionary Defense Fleet. Despite this, the Aristocra frequently attempted to meddle in Fleet operations. This rivalry between the Syndicure and the Council frequently resulted in Council members endeavoring to "reiterate" to the civilian leadership that the military fell under the Council's authority.