Watching the action in the House of Representatives last week, it was easy to imagine that immigration was a strictly partisan issue. The bill under discussion, mostly the brainchild of Judiciary Chairman James Sensenbrenner, was about as tough as it gets: not just 700 miles of border fence and stiffer penalties for employers who hire illegal immigrants but also a provision that turns illegal presence in this country from a civil violation into a federal crime -- subject to an entirely different kind of policing and punishable by much stiffer penalties. Over two days of emotional debate on the floor,...