Only thing I can think off for arrests is making an FL hook command.
When a player's ship is low on health ( say 15%) a police id-ed player can type /arrest <pirate name>
unless you are a very fast typer, a pirate who still has botts will regen before you can finish the command.
this command only works on pirate id-ed ships.
The pirate's ship is then beamed to Bastille or something for 4 hours. after that it gets beamed back to its last docking point.
I have no idea if something like this is even possible. but I think it would make being a cop more fun.
and cops in general will become more dangerous to pirates if they can throw you in the slammer.
This will also allow navy to call in cops for a reason. the navy disables (damages) a pirate's ship, and teh cops come to throw him in the slammer.
hell, like stoat says, this could even work for hunters and the lsf or something.