I have already played in argonath server for 3 days as officer altrough for you is to little, and i came with following ideas
that police could enter any house and garage to investigate that player doesn,t have a controband or narcotics etc.
second idea is to add comand to police /ticket so police could give a player ticket fo reckless driving,driving without a license.
and third idea when like suspect is surendered the police could do comand /arest [id] and when suspect is arested he will lose control of walking and shooting and will follow police oficer like a gang member in single player of san andreas when you press g on your gang member, so he can follow you, and then you can easily put him in jail. thats all. and sorry for my english i am from Lithuania