Unless you have a problem with potential enforcement abuse, ie racial profiling, your criticism of the new AZ law must mean you are for open borders.
If you have a problem with potential enforcement abuse, Hacker, Flash, spekio, etc, how the hell do you live with the awesome power of deadly force and arrest police already have? If you feel this law is more prone to abuse, then how can you possible support any immigration law? Are the Border Patrol less likely to racially profile in there enforcement of the federal law, almost verbatim the AZ law, then a Phoenix or Tucson police officer? Do you really believe that it is safe to trust the judgment of cops when deciding whether it is legal to enter a private house w/o a warrant due to exigent circumstances, but not trust their judgment when enforcing this law? Mistakes are made by the police all the time. Sometimes, very rarely, they even knowingly disregard policy and even more rare break the law. But when a cop uses bad judgment in a shooting, we don't take their guns away or change the law to require they be shot at before shooting back, thereby clearly establishing deadly intent and removing judgment from the officer. So why the hell are we so concerned about a POTENTIAL abuse in such a relative way? This potential abuse would result in someone being questioned for mere minutes and sent on their way. Face it, the down side is minimal. If abuse is on purpose and based SOLELY on race, then it is a constitutional abuse, I will give you that. But getting shot by the police for the wrong reasons is a fourth amendment abuse of the highest order, and we trust out police with the continued option to enforce the law and protect the public with guns.
The AZ law specifically prohibits racial profiling and the governor ordered new training specific to enforcement of this law. We trust cops with far more power then require to enforce this law, and no complains about that. I see no reason we can not go forward and simply watch for abuse just as we do in every arrest and public contact made by police. The courts will deal with the very rare abuses just as they do now. I personally believe that most people screaming about the fear of profiling are simply open border people, or at the least, very sympathetic to illegal immigrants and can't bear to enforce our laws again them.