1/3 of our population is illegal? Bull$hit! You are trying to tell me we have over 100 million illegal aliens here? LOL
This law allows Law Enforcement to look at someone and say "PAPERS PLEASE!".
It violates the 4th amendment, this is the amendment that protects you from unreasonable searches and seizures. The Arizona law does not require probable cause and allows a law enforcement officer to look at someone and just ask them (require) them to prove citizenship.
This violates the 14th amendment which is the equal protection clause, guaranteeing equal rights for everyone. I can't imagine too many blue eyes, blondies are going to be stopped. If you are brown you will get stopped, but guess what, not everyone that is brown is illegal.
I have no problem if you are stopped for a traffic infraction or anything else which would be probable cause, for LE to check citizenship status if it can be done quickly. I myself have no way to prove (in person) that I am born in this country. Your driver's license or I.D. does not contain that information. I do not have a passport, and usually do not carry my birth certificate with me. Sure a full background check will provide that info but that is not really something you can do while waiting on the side of the road.
On top of that, what will it accomplish? So you detain the guy because he is illegal? You turn him over to ICE they give him a ride back to Mexico and he is back here in two days? Maybe you want to put someone in prison? Great idea! Lets house them, feed them and overcrowd our prisons even more, maybe you can bunk them with all the pot smokers that are also VERY dangerous (sarcasm).