The monarchia Sicula (Sicilian monarchy) was a historical but unduly inflated right exercised from the beginning of the sixteenth century by the secular authorities of Sicily (presently in Italy), according to which they claimed final jurisdiction in Catholic matters, independent of the Holy See.
They premised this right on an old Papal privilege. The oldest document advanced in support of their claim was a Papal Bull of 5 July 1098 by Pope Urban II to Count Roger I of Sicily. The Pope agreed not to appoint a Papal legate to Sicily against the will of the Count and declared his intention of permitting the Count to execute ecclesiastical acts in Sicily that were ordinarily executed by a legate (quinimmo quae per legatum acturi sumus, per vestram industriam legati vice exhiberi volumus). Pope Paschal II, in a Bull of 1 October 1117 addressed to Count Roger II of Sicily, confirmed and clarified this privilege. He gave Roger II the same power "in the sense that if a Papal legate be sent thither, that is a representative of the Pope, you in your zeal shall secure the execution of what the legate is to perform" (ea videlicet ratione, ut si quando illuc ex latere nostro legatus dirigitur, quem profecto vicarium intelligimus, quae ab eo gerenda sunt, per tuam industriam effectui mancipentur).
Pope Urban II thus had granted Apostolic legatine authority to the secular authority of Sicily; according to the Bull of Pope Paschal II this meant that, when a Papal legate was appointed to Sicily to exercise jurisdiction in certain ecclesiastical matters as the Papal representative, he was required to communicate the nature of his commission to the secular authority, which then would execute the Papal acts so commissioned in place of the legate (legati vice). In both instances it was a question not of a jurisdiction of the Prince of Sicily independent of the Holy See, but only of the privilege of the secular authority to execute ecclesiastical acts as a deputy of the Catholic Church; in other words, the sovereign of Sicily was privileged, but also obligated, to execute Papal regulations in his jurisdiction (of Sicily).
As a result of the feudal relation between the Princes of Sicily and the Pope, ecclesiastical matters there were more political in character than elsewhere, and the Catholic Church in Sicily was reduced to the greatest dependence upon secular authority. However, up to the beginning of the sixteenth century, the privilege bestowed by Pope Urban II was never invoked or even mentioned. When Ferdinand II of Aragon became King of Sicily, his secretary, Giovanni Luca Barberi of Noto, Sicily, undertook to collect the documents by which the rights of the Kings of Sicily, both in ecclesiastical and secular matters, were determined. To this collection, denominated the Capibrevio, was joined a collection of documents titled the Liber Monarchiae (Book of the Monarchy), meant to prove that the Sicilian monarchs always had exercised spiritual authority. The Liber Monarchiae first published the legatine privilege conferred by Pope Urban II.
The Kings promoted it as a legal basis of the purported authority that they had long exercised over the local Catholic Church. They also used it to extend their pretensions that, by virtue of an old Papal privilege, they possessed ecclesiastical authority in spiritual matters independent of the Pope. Despite doubts expressed concerning the authenticity of the document, Ferdinand declared on 22 January 1515: "As for the Kingdom of Sicily, where we exercise the supervision of spiritual as well as of secular affairs, we have made sure that we do so legitimately". In consequence of such an exorbitant claim, disputes arose between the Popes and the Sicilian monarchs. Pope Clement VII negotiated with Charles V, Holy Roman Emperor concerning the "monarchia Sicula" ("Sicilian monarchy"), but without success. In 1578 Philip II of Spain tried vainly to obtain a formal confirmation of the right from Pope Pius V. In 1597 the King appointed a special permanent judge ("Judex Monarchiae Siculae") to give final decisions in the highest ecclesiastical causes, an appeal from his judgment to that of the Pope being forbidden. The Judex Monarchiae Siculae claimed the general right to visit convents, supreme jurisdiction over the Sicilian Bishops and the Clergy, and the exercise of a number of episcopal rights, such that Papal authority was almost wholly excluded.