Can a cop view someone's Facebook profile and messages without the person knowing and without their permission?

[trai]

"Can a cop view someone's Facebook profile and messages without the person knowing and without their permission?" Of course. Anyone can, including the police. It is publicly accessible information, which have posted of your own volition.

"if I change my password can he still view my profile?" Your password only secures the account settings for your profile, and has nothing to do with others reading your posts. That's a simple as your account being set to "public," or merely that person having a friend in common.

"can you get introuble with the law for saying something bad on Facebook" One gets into trouble with law enforcement for violating a statute in that jurisdiction. Whether or not what you have written constitutes a violation of any statues, we cannot guess, since we don't know what you wrote or where you are.