How is someone's constitutional rights being violated? If an officer stops you for a valid reason (the way I read the bill, they cannot just walk up and stop people for no reason, but I'm sure you'll tell me if I am mistaken) the officer has a right to ask for id. If legal id is produced, no problem. If none can be produced, you can be detained on suspicion of being in the country illegally (which is a crime you know). How is any of that a constitutional violation?
I'm still catching up on this thread, so this might already have been addressed, but:
I suspect that this will violate the equal protection clause. If a white driver is stopped, but doesn't have a valid ID for whatever reason (maybe he left his wallet at home), is he going to be detained? Probably not. If someone with brown skin is stopped, but doesn't have a valid ID, he's going to be detained.
And I have questions about the legality of detaining people over a simple failure to produce an ID. I know that in a lot of jurisdictions, the police can ask your name, but can not demand that you show ID. Having a picture ID is not a requirement to live in our country (although having a picture ID is necessary to engage in many forms of commerce).