Also: My perspective as a police officer on this Arizona law.
I don't want to come down *too* hard on the law simply based upon the fact that I'm a police officer in Canada, and I don't know the environment of policing in southern states with a high hispanic population. I don't know the community, I don't know the dynamics.
But my instinct is simply that I don't see what "reasonable" suspicion might entail to lead an officer to think that someone is an illegal OTHER than that which leads to unacceptable racial profiling.
MAYBE situations through talking with witnesses where they can provide evidence that someone is an illegal, or through talking with an individual in the course of regular duties where they make statements that provide the officer with "reasonable suspicion" but other than that....
It's not even like, for example, a drug investigation, where you can profile someone based upon their actions, gestures, clothing, smell, or behaviour to articulate a reasonable suspicion or belief of criminal activity. As someone who supports and defends the law enforcement community generally, this is a bad law that will almost certainly lead to the potential for unacceptable racial profiling, even by good officers.
edit: and to drunkenly paraphrase someone else I read on this subject in the past couple days: Any law that might result in the regular demand by law enforcement in the United States of America of "papers, please" is an awful, horrible law.