I have seen a few instances where Judges of realms have been secretly working for / spying for another realm, and when found out have banned as many nobles as they could get their hands on before leaving the realm. Most recently this happened in Cathay on FEI, where the Judge was found to be a spy for an enemy realm and apparently banned half a dozen or more nobles before leaving.
This has always seemed rather lame and almost an abuse to me, as really, once a noble has been discovered as a traitor, who is going to listen to them, Judge or not? Who's going to enforce these bans issued by a traitor? What are other people's opinions on this?