The problem is that much of the law is poorly written. (BTW, I voted in favor of it). There are questions as to whether a EMT or rescue personal must check id before providing emergency services and other things. The basic idea is sound, but they left a lot of the finer questions open. I believe that it will be found unconstitutional based on it being too vague. However I voted becuase it was more of a message thing rather than believing it would stand up to a legal challenge.
Sad thing is, much like drugs and booze, the only way to ever stop UDA's is to cut off the demand. As long as busineses, be they corporations like Wal-Mart or small ones, can hire UDA's without any fear of having the crap fined out of them, the UDA's will come. Only by making it more expensive to hire UDA's will people quit using them. And only when there isn't a demand for their services will they stop making the dangerous trek across the border.
And neither party, despite what the Dem's say, want to piss off corporate America enough to enforce currant laws against the hiring of UDA's.
No demand, no supply.