It's fairly evident that this move is actually political positioning by Gov. Brewer.   Arizona, like some other states, is facing a deficit.    Gov. Brewer has indicated she might be open to raising some taxes.   This of course is anathema to the Right---which of course includes huge numbers of Republicans.   In order for her to win the tough Republican primary coming up soon, she had to try to win back conservatives (and reactionaries).   By signing this bill, she has in fact done this.

It's also fairly evident that this law will not stand. Court challenges will stop it. So Gov. Brewer will be able to say to the Right:   "Look, I did what I could on this issue."

It does force the President's hand to try to do something about a path to citizenship for illegal immigrants, an issue he had not planned to deal with this year. Of course this is also partly due to pressure from Sen Reid, also facing a strong challenger, this time in the fall election.

More later.