Doug, from what I've read of the AZ law, the language isn't that clear. I believe it says something like "any lawful contact" by the police, and that term is too vague to suit me.

We already have hundreds of unarmed people being shot and killed by police because the police officer "thought his life was in danger" or "thought he might be armed."    It is very easy to find some "lawful" reason to stop and question someone.   They spit on the sidewalk or maybe were sitting on it, or they "appeared intoxicated" or they "fit the description" of a suspect or they were jaywalking, etc., etc.   

And if I understand the law correctly, if someone calls the police and says "I think those people in Apt. 2-B at such and such address are illegal," some cops may think that's sufficient reason to ask them to show proof of legal residence.   

Anyway, as I said before, a major intent of this law (not officially, of course) is to make Hispanic US citizens fear harassment (or worse) by the police -- e.g., if and when they try to vote.

Until the AZ officials really start cracking down on the businesses that employ illegals, and making the penalties for them very stiff, I won't be convinced that this law is primarily about deterring illegal immigration.