When Senator Mitch McConnell barred Senator Elizabeth Warren from speaking during the debate over Jeff Session’s nomination for Attorney General, he invoked Rule XIX. It's safe to say many people suddenly realized how little they knew about the rules of the Senate. There are in fact 44 standing rules of the US Senate, but what are they? Where do they come from? And who can Presiding Officers turn to when they have a question? Alan Frumin spent 35 years in the Office of the Senate Parliamentarian and he gave us a primer.