The magic question: "am I being detained?", seems to stop everything.

I'm not a fan of the question "Am I free to go?"... I'm not sure if a Police Officer must say yes or make himself liable but the question suggests an uncertainty in the one asking the question and may give the Police Officer the presumption of jurisdiction as if the one asking is asking for permission to go...

For some reason - "am I being detained?" always stops the show.

The best question to ask is: I'm I a CITIZEN ofiicer ? :D

the movie robocop, he called out the name 'citizen'... never answer to being called ANYTHING but your name... except with, 'i'm sorry, you must have the wrong guy. can I be of assistance to you?

https://www.youtube.com/watch?v=yi6scLZLrMw&feature=c4-overview&list=UUzync0OG2qvKRt4U22HNyeQ