It does not just makes an effort to enforce the law, it (appears to me, will see how it actually gets applied) adds penalties, at least detention/arrest, even for US citizens !
B. FOR ANY LAWFUL CONTACT MADE BY A LAW ENFORCEMENT OFFICIAL OR AGENCY OF THIS STATE OR A COUNTY, CITY, TOWN OR OTHER POLITICAL SUBDIVISION OF THIS STATE WHERE REASONABLE SUSPICION EXISTS THAT THE PERSON IS AN ALIEN WHO IS UNLAWFULLY PRESENT IN THE UNITED STATES, A REASONABLE ATTEMPT SHALL BE MADE, WHEN PRACTICABLE, TO DETERMINE THE IMMIGRATION STATUS OF THE PERSON. THE PERSON'S IMMIGRATION STATUS SHALL BE VERIFIED WITH THE FEDERAL GOVERNMENT PURSUANT TO 8 UNITED STATES CODE SECTION 1373(c).
So an American could be detained for 'reasonable suspicion' unless they carry their papers (at least until the status is verified); moreover
E. A LAW ENFORCEMENT OFFICER, WITHOUT A WARRANT, MAY ARREST A PERSON IF THE OFFICER HAS PROBABLE CAUSE TO BELIEVE THAT THE PERSON HAS COMMITTED ANY PUBLIC OFFENSE THAT MAKES THE PERSON REMOVABLE FROM THE UNITED STATES.
It would seem to me that an *American* could be arrested just for not having/presenting their papers, since that could be construed as probable cause ... that hasn't been in federal law.