You have to see it to believe it:
I worked on Capitol Hill long enough to know that most Congressional hearings have nothing to do with gathering information; they're dog-and-pony shows intended to showcase an issue. I've never seen one actually converted into a union rally before - especially with the blessing of the Committee Chairman.
If union thugs are willing to boo, hiss, and throw things while a Senator is speaking in a Senate hearing room, with police on hand, what will they do to opponents of union organizing far from the cameras?
Update: I've heard from a Senate staffer who tells me that the the microphone failed to pick up just how loudly people were booing and hissing at Alexander when he spoke. He also says that no one had thrown anything when Harkin made his warning -- at least not yet.