In some areas (like Sunnyvale CA) you become an Emergency Responder and can alternate from police work to fireman (or EMT) every few years. I heard it described (by someone who was a policeman at the time) as going from hero to villain and back.

http://sunnyvale.ca.gov/Departments/PublicSafety/Recruiting....

I agree. I think it helps them see the people they "serve and protect" as better humans, and themselves as something other than the most righteous thug.