Quote Originally Posted by MattKing View Post
I've not only met police officers, I've cross-examined them under oath .

It helps to understand a bit where they are coming from.
The difference probably lies in what your relationship to the police officer is. A person accused of a crime (and I mean even a stupid thing that's not a crime, like photographing something from a public street) may find that pointing out where a police officer is wrong is just going to increase his immediate hassles, no matter how politely he points that out. The exception might be where the police officer does in fact realize (s)he is wrong and understands the legal ramifications of arresting someone for something that isn't illegal (of course they can invent all sorts of things anyway; disorderly conduct or some such crap).

I mean, if you're some kind of fellow officer (customs you said?) or other person in the legal system, you're going to have a very different experience of the police you meet - you're not going to be under their authority, dealing with the pointy end of their figurative stick.