This topic is a doozy.
I read the NY Times article by the UMKC guy who helped write the bill, and he makes some seemingly reasonable points about this thing. Then I read the NPR interview, where he had to respond to critics of his bill.
http://www.npr.org/templates/story/story.php?storyId=126390888Basically, I came away believing that the objective merits of the main argument against the bill are weak....which is "Dude, you know fracking cops are going to abuse the crap out of this." And, simultaneously, the most persuasive subjective argument against the bill are dead on. Cops ARE going to abuse the crap out this. No reasonable person can argue this point given the great weight of history on these types of things.
However, it seems pretty air tight. Can't due much to fight it, IMO.
I'm against it, but just because I'd rather see them handle it differently......more secure border, etc.