Heads of State generally enjoy the greatest inviolability, although some States allow impeachment or similar constitutional proceedings, in which the highest legislative or judicial authorities are empowered to revoke the mandate of the Head of State for exceptional reasons. It may be an ordinary crime, a political sin, or an act by which he or she violates such provisions, such as an established religion, binding on the monarch. Under a similar procedure, an initial mandate may be invalidated. In parliamentary constitutional monarchies, the legitimacy of the unelected head of state typically derives from the tacit agreement of the people on the elected representatives. Only a very small minority of all executive agreements concluded rested exclusively on the powers of the President as Commander-in-Chief and organ of external relations; The rest has been approved in advance by Congress by law or by contractual provisions ratified by the Senate.440 Therefore, consideration of the constitutional importance of executive agreements must begin with a distinction between the types of agreements grouped under this title alone.441 In Roman Catholicism, the pope was once sovereign pontiff and head of state. First, the politically important ecclesiastical state. After Italian unification, the pope remained head of state of Vatican City. In addition, the Bishop of Urgell is ex officio one of the two co-princes of Andorra. .