There's a really classic cliche every time you switch the TV on - you see cops arguing. I have spent a day a week for many years in the presence of police and I have never seen them argue. It's a military hierarchy. They do what they're told. There's no bickering.
“You want to try and bring a character to life in an honest a way as you possibly can. It doesn't matter whether he's a doctor, an actor, a car salesman or a captain of a starship. If you can bring truth and honesty to that character, then your audience will believe you.”