As a reminder that this is not an issue on which people on the left are all lined up on one side, here's a link to a powerful piece by Nat Hentoff a couple of days ago in the Village Voice.

And I've just been listening to George Galloway, about the most left-wing MP, expelled from the Labour Party for opposiong the war in Iraq making the same points on BBC Question Time - there's a video link of it here for the next week.

My point is, treating this as a purely partisan political issue is unworthy, whoever does it.