Quote Originally Posted by [b
Quote[/b] (Ludens @ July 24 2004,11:06)]About the pope, the rules for excommunication are the same for all catholic factions, including AI ones. The only exception is the Pope, who cannot get excommunicated for attacking. The rules are:
Quote Originally Posted by [b
Quote[/b] ]The rules for excommunication is quite simple. If a faction with twice the number of regions attacks, he gets a warning. Any aggressive action before the warning runs out leads to excommunication. Sally out of a besieged castle is not aggressive (since the patch) but retaking lost a region does count as aggressive. Attacking the papist is automatic excommunication. Blocking a crusade in conquest mode is automatic excommunication, in glorious goals mode it depends on if the crusade's object is a goal or not.

Being friendly with the pope has no effect on the rules. But he will send you cash if he has any spare.
This information comes from Eat Cold Steal, one the developers (taken from the beginner's guide).
I know how it's supposed to work by the book, but I don't understand why other catholic factions controlled by the AI can attack my shipping and hold one of provinces under siege for a few years and get away with it. I had an it is likely to last for 9 years german siege situation. So I thought I'll wait this out and they'll get excommunicated after two and then launch my crusade from wessex as a counter attack. The Italians attacked my shipping and sunk quite a few vessels but my ships managed to sink alot more of theres defensively. I retaliated and sank one of their galleys off the spanish coast:

...a warning from the pope...

I really do think that the pope favours the AI