On chapter 8 (your third trip to Hell's Kitchen), you must knock out or kill every UNATCO and MJ12 trooper plus any cops that are around after talking to Dowd or Smuggler. This must be done on Realistic difficulty.
Keep an eye out for a sniper on the rooftops; He needs to be taken out as well.
The name of the achievement is a shout-out to the Malkavian Mod for Deus Ex.