If you want a realistic police game. Look no further than GTA V. You can download the RAGE Plugin Hook and play single player as a police officer (patrol cop). You can write tickets, answer calls, write parking tickets, run license plates and ID's, etc. It's the best thing I've seen in a while. There is also one that I played for GTA IV, it currently has multiplayer support (the V version does not), and it has a plethora of mods to download also. To get the Liberty City or Los Santos first response mods, you can go to (http://www.lspdfr.com).
If you'd like to see the mods in action, then you can check out my Twitch page (http://www.twitch.tv/fadedcalicojack), and see what mods I am using and how they look in game as I play almost every day. You can PM me here or through Twitch, and I will even help you set it up via teamspeak.
FadedCalicoJack
Just here to help others have an enjoyable gaming experience!