excommunication

This [Magna Carta] has been forced from the King. It constitutes an insult to the Holy See, a serious weakening of the royal power, a disgrace to the English nation, a danger to all Christendom, since this civil war obstructs the crusade. Therefore†we condemn the charter and forbid the King to keep it, or the barons and their supporters to make him do so, on pain of excommunication.

—Pope Innocent III originally Lotario de' Conti di Segni