Declassify Mission: Use Cleavers only
You'll be in a heavy firefight at the start of the section. Take cover and take out enemies without exposing yourself too much. You may want to concentrate your fire on the reaver first to lessen the threat in the area. You'll find the declassify mission marker near the stairs. It's okay to kill the reavers and other locusts first using ranged weapons before activating the declassify mission.
Before moving upstairs, look around in the courtroom to find a COG tag skull in one of the raised platforms there. You'll find the COG tag on top of the same tribunal platform where the skull is painted.
Head to the exit and take out the enemies using your cleavers. Your allies will most likely rush themselves so just join the fray and slice and dice enemies from the sides. Just remember to roll out of the way when you're wounded.