Arizona, although Constitutionally barred under Article 1 Section 8 Paragraph 4, is 'Fed'-up with this mess.
I was recently made aware of a California law that was struck down a few years ago. It was very similar to the recently signed Arizona law. California, already short on dinero, felt it needed to defend it's law in court and spent lots of that quickly diminishing dinero to do so.
I can't recall the details but some law enforcement agency in the Midwest decided to enforce immigration law. The federal government responded by no longer answering the phone. That left them unable to deal with the illegal aliens they already caught.
You don't tug on Superman's cape, you don't spit in the wind, don't pull the mask off the Lone Ranger and don't mess with the federal government on immigration.
Arizona can't go around asking people for "papers". Arizona cannot enforce immigration law without getting the federal government's permission and cooperation. Arizona cannot take that permission through legislation, it must be given.
I sympathize with Arizona's plight but they must act within the rules. The rules say they cannot take on immigration law themselves. If these illegal aliens are breaking state laws then enforce state laws. Trespass, murder, kidnapping, vandalism, theft, and so on are state law and can be enforced against even illegal aliens. Find them, charge them, send them to court. Even illegal aliens deserve a fair trial. If found guilty then send them to prison for a very long time.