ABDICAZIONE. - This word, which in ancient Roman law served to indicate every kind of renunciation, and later took on the specific meaning of renunciation of a public office, and also of expulsion

According to the most widespread opinion, a formal acceptance by parliament is not necessary for its validity, it being sufficient that the sovereign's will is clearly expressed in an authentic act. This does not preclude, however, that particular provisions, to be issued by means of a special law, may prove opportune, especially for the purpose of declaring the legal consequences of abdication with regard to the future descendants of the abdicating king. Furthermore, it is universally admitted that abdication cannot be subjected to a condition or a term and that it exerts no influence upon the order of succession to the throne.
The institution of abdication is not unknown to canon law; indeed, during the Middle Ages, the question of whether or not the Pope could renounce the exercise of his authority was the subject of lively dispute (v. SOMMO PONTEFICE).