Many cops, attorneys and others have used the classic good cop/bad cop tactic to try to force concessions or confessions. The key of course is not to admit that you are just doing good cop/bad cop. That seems to have escaped Iranian negotiators in the ongoing nuclear program talks who have been giving interviews bragging about how they are screaming at American and other diplomats in a good cop/bad cop ploy. Hmmmm. It is nothing like a man screaming like a lunatic to convince you that he and his country should have access to weapons-grade nuclear material.