The Corascant Security Force or CSF was composed of a bunch of lazy idiots who sat around all day smoking death sticks and watching stormtroopers brutalize innocent bystanders. Way back in the prehistoric days before the founding of the jedi there were ounconfirmed reports of th CSF actualu doing somthing, but historians remain skeptical.
After the Rebels took over Coruscant, they fired the majority of the orrigional CSF and replaced them with their own bunch of loosers. According to eyewitness reports, the new CSF crew actualy did some work, but it was all useless, They did random seccurity sweeps through the palace while missing an imperial spy systmen that was literally under their noses. The new cheif of the CSF was an obnoxios fat guy who thought that killing over 12 imperials is a sure sign you are an imperial spy, and as such he unseccsesfully tried to detain the majority of the rebel alliance, but settled for arresting Mara Jade after She saved the day without his permission.