I would want to be pretty confident with my knowledge before I started questioning what a cop was asking. At the minimum I would want to have a decent lawyer on tap to tell me the reality versus what i thought.
That's my point: we should all be very confident in our rights and responsibilities as citizens.
Should be a class in school.
Abdicating that responsibility to the cops who probably know little more than most people is a great way to get yourself even deeper in trouble.
The videos by lawyers in the States about not ever speaking to police, because this is what they do with whatever you say, are bloody scary.
Off topic though, sorry.