The members are part-time, and while there are dedicated professionals in the ranks, many 'weekend warriors' also signed up because they watched too many vid-slugs.

Their uniforms vary wildly from block to block (and artist to artist) and are presumably modified.

The idea of the Citi-Defs is that they will defend their blocks from disaster or attack and assist the Judges. In practice, the Citi-Defs are often inadequately trained, full of bored and belligerent citizens, and often cause problems: Citi-Defs has been involved in block wars, disastrous training exercises, secessions, and the like.

The Chief Judge only places them on active alert during emergencies for fear of what they might do otherwise. During Chaos Day, enraged Citi-Def units were a critical threat that drove the Judges out of sectors. Their most prominent positive role was in the Apocalypse War. Citi-Def soldiers fought bravely against the East Meg One invaders, working directly with the remnants of the Justice Department. They subsequently fought for the city during Judgement Day and in Nero Narcos' Second Robot War, and some loyalist groups helped the Judges secure blocks during Chaos Day.

My Def squads are from the Dan Abnett Block in Sector 102 and are known as the Bluebloods (named after a Gaunt's Ghosts regiment written by Abnett). They are incredibly proud and arrogant, believing themselves to be better than those around them, leading them on more than one occasion to take the law into their own hands. Created by the now self-titled Captain Sturm after discovering a copy of Blueblood, the squad has grown in power and resources and has influence over the Block Board, allowing them to control more of the Dan Abnett block.