[Suteisi]

One time in a parking lot I was meeting a friend and a man showed up and started asking me what I was doing there. I told him I was meeting a friend and when he pressed with more questions I told him I wasn't going to answer any of his questions unless he showed me a piece of ID stating he was a police officer or a member of some kind of law enforcement. He didn't and left.

You have the right to ask for ID if something like this happens to you. Police officers know and will show their ID before even asking questions.

You have the right to refuse to answer any questions and/or show anything to them. Unless the provide a valid piece of ID and it's clear why they wish to interogate you.

Police officers generally don't have the right to question or arrest anyone unless they have a valid reason to do so. That's how it works out here in Canada anyway, and Canada used to be a dominion of England sooooo yeah.