In the cities of the future these are the
Judge,
Jury, and
Executioner. When society is housed in enourmous cities that are powder kegs just waiting to explode then
Justice must be fast and final. The judges are bred and trained to mete out justice consistantly and preserve the peace in their society from the back of their LawMaster bikes,
LawGivers in hand.
The adventures of probably the greatest megacity judge of all, Judge Dredd, are chronicled in 2000AD and other magazines.