Motu proprio is the name given to a certain type of Papal rescript , where the clause motu proprio (of his own accord) is used, signifying that the provisions of the rescript were decided by the pope personally and not by a cardinal or other advisors. It is normally in the form of a decree, resembling a Papal Brief except that it is not sealed and countersigned. The first Motu proprio was issued by Pope Innocent VIII in 1484. It continues to be a common form of rescript, especially when establishing institutions, making minor changes to law or procedure and when granting favours to persons or institutions.

A motu proprio rescript begins by giving the reasons for issuing it, and continues to describe the law or regulation being made or the favour granted. The Pope personally signs it, with his name and the date in Latin. It is then issued from the Dataria Apostolica , with the original text normally in Italian or Latin. A rescript containing the clause is valid even when counter to Canon law or previous instructions from the Pope.