1. Constabulary of the Lord: clerics of state religion use detection magic, blunt instruments to maintain adherence to byzantine regulations, raid establishments offering forbidden bills of fare, come through windows at night to enforce sexual mores, it's horrible
2. Law enforcement province of single noble family, once-honorable lineage degraded into rabble of hoodlums, corruption/graft old and deep, arrest aristocrats in showy fashion from time to time just to send a message
3.Biggest jerks in town spend months training for annual brawl to determine who wears the badge of station, losers form posse, arbitrary justice-by-mob, beat-downs/summary executions issued as mood takes them
4. Trial by Democracy: all citizens authorized to make arrests, do so enthusiastically, entire population must participate in grueling schedule of rigidly timed weekly trials in Colosseum of Law, no one eats until docket is cleared
5. Money changers/lenders hire private armies, everybody else hires bodyguards, disputes settled by proxy fights or at gaming tables
6. Masked crime-fighter w/incredible fighting skills/selection of magic items patrols rooftops, frequently silhouetted against moon, empowered to enforce quirky personal interpretation of law
7. Children on patrol: according to city constitution, only those who haven't yet reached their majority may adjudicate disputes, operate outside of law
8. Hired monsters from nearby dungeon environment patrol streets, ensure close to 100% compliance with curfew, otherwise its a free-for-all, city council has appointed special commission to look at alternatives
9. Seer-detectives levitate in lotus position, monitor events w/clairvoyance, dispatch troops as needed from central Dome of Contemplation (the one with the giant rotating eyeball on top)
10. Highly trained justice hounds sniff out wrong-doing unerringly, bay at criminals in their lairs like treed raccoons, handler goons do the rest
11. Ancient sage hobbles around adjudicating disputes Hammurabi-like, citizens heed unquestioningly all wisdom dispensed even when completely bizarre
12. Tribunal of Idiots: cultural quirk passed down from time immemorial that everyone just accepts, tries cases by instinct alone, non-evidential hearings involve much staring into eyes to know intent, idiotic utterances interpreted by highly influential class of fool-augurs