[quote="Msecc27, post:1, topic:329599"]
What's the difference between Papal Encyicals, Apostolic Constitutions, motu proprios and Papal Bulls?
I'm sure I'm missing other kinds of Papal documents, but when is each one used what difference circumstances are they used under?
Modern Catholic Dictionary:
ENCYCLICAL. A papal document treating of matters related to the general welfare of the Church, sent by the Pope to the bishops. Used especially in modern times to express the mind of the Pope to the people. Although of themselves not infallible documents, encyclicals may (and generally do) contain pronouncements on faith and morals that are de facto infallible because they express the ordinary teaching of the Church. In any case, the faithful are to give the papal encyclicals their interior assent and external respect as statements of the Vicar of Christ. (Etym. Latin encyclicus; Greek enkyklios, circular, general.)
An encyclical epistle is like an encyclical letter but addressed to part of the Church, that is, to the bishops and faithful of a particular area. Its contents may be doctrinal, moral, or disciplinary matters of universal significance, but may also commemorate some historical event or treat of conditions in a certain country or locality.
APOSTOLIC CONSTITUTIONS. Collection of ecclesiastical laws from the fourth century. Their most important part is the set of eighty-five canons, attributed to the Apostles, dealing with ordinations, official responsibilities, and the moral behavior of bishops and priests. They eventually became the basis for canon law in the West.
MOTU PROPRIO. Words used in rescripts drawn up and issued by a pope on his own initiative, and not conditioned by any petitionary requests. The documents are always signed personally by a pope.
BULL, PAPAL. The most solemn and weighty form of papal letter. The name is derived from the Latin bulla, the disklike leaden seal attached to such a document. It is used by the Pope in appointing a bishop. Formerly all papal letters of major importance, including canonization decrees, were called bulls, but the current Acta Apostolicae Sedis gives some of these papal letters various names.