It's strange to hear so-called "conservatives" try to overlook the clear provision in the US Constitution that requires all searches MUST be supported by WARRANTS. Thus, a police officer cannot compel you to show ID without first obtaining a warrant.

http://www.reuters.com/article/idUSTRE66R45C20100728

The provision in the AZ law that requires residents to have the "proper ID' to obtain a legal job is also unconstitutional, because it violates the "Contract Clause", which prohibits all states from interfering in private contract.