The unfortunate truth is the practice of questioning citizenship, screening travellers and those in businesses has been in practice for years through ICE's LEAR program. SB 1070 is simply redundant to many local law enforcement agencies. The Arizona Sheriffs Association opposed the SB 1070 because local complaintants may file lawsuits against local police departments with claims federal immigration laws are not being enforced. Protections were factored in the bill late for vindictive and frivolous lawsuits.
Laws like SB 1070 alter the role of the federal immigration enforcement officer on the ground. The range of their job description is swiftly changing due to programs like Secure Communities and E-Verify. These multiplying laws, policies and programs sustain a chorus of practices to randomly demand citizenship and identity for anyone police may approach in the line of duty.
A strange irony is that an amendment to reject national ID policies was written into SB 1070 before its passage through the Arizona Senate.