Catholic Encyclopedia (1913)/Motu Proprio
The name given to certain papal rescripts on account of the clause motu proprio (of his own accord) used in the document. The words signify that the provisions of the rescript were decided on by the pope personally, that is, not on the advice of the cardinals or others, but for reasons which he himself deemed sufficient. The document has generally the form of a decree: in style it resembles a Brief rather than a Bull, but differs from both especially in not being sealed or countersigned. It issues from the Dataria Apostolica, and is usually written in Italian or Latin. It begins by stating the reason inducing the sovereign pontiff to act, after which is stated the law or regulation made, or the favour granted, It is signed, personally by the pope, his name and the date being always in Latin. A Motu Proprio was first issued by Innocent VIII in 1484. It was always unpopular in France, where it was regarded as an infringement of Gallican liberties, for it implied that the sovereign pontiff had an immediate jurisdiction in the affairs of the French Church. The best-known recent example of a Motu Proprio is the instructions issued by Pius X on 22 November, 1903, for the reform of church music.
The phrase motu proprio is frequently employed in papal documents. One characteristic result of its use is that a rescript containing it is valid and produces its effect even in cases where fraud would ordinarily have vitiated the document, for the words signify that the pope in granting the favour does not rely on the reasons alleged. When the clause is used in dispensations, the latter are given a broad interpretation; a favour granted motu proprio is valid even when counter to ecclesiastical law, or the decisions of the pope himself. Consequently, canonists call the clause the "mother of repose": "sicut papaver gignit somnum et quietem, ita et hæc clausula habenti eam." (See RESCRIPTS.)
REBUF, Tract. concordatorum: De forma mandati apostol. (Paris, 1538), s.v.; RIGANTI, Comment, in regul. cancellariæ apost. (Rome, 1744), , s.v. Gratia moto proprio; GIRAUD, Bibl. sacra (Milan, 1535).
A. A. MacErlean.