Actually Durka, you are already obligated to identify yourself to the authorities. If they have reasonable grounds to believe you match a description, believe you are committing or have committed a crime. Or the Police are looking for someone in particular.
In this case, they are looking for someone in particular, illegal immigrants. It just so happens that the issue pertains to a specific group of immigrants. Thus visual appearance is a factor.
If you are a legal immigrant in Arizona, get some ID and you'll be fine. Given the severity of the problem, this is a reasonable course of action.
This is what happens when civil rights trumps commonsense for to long. Just as the US has to expect blowback for erroneous foreign policy. Immigrants and civil liberty groups, have to expect blowback when there actions create intolerable situations.
Bear, obviously one will have to identify one's self if you are pulled over (required) or if you are a criminal suspect.
So legal citizens of a country can have their civil rights violated on the pretense of them looking "mexican"?
I would assume Arizona residents have state issued ID, the point is they shouldn't have to prove that on demand due to them looking "mexican".
Rounding up illegal immigrants is one thing but when legitimate citizens get caught up in this snare is where it becomes intrusive & unlawful.