Apostolic constitutions (apostolicae constitutions): solemn, formal documents on matters of highest consequence concerning doctrinal or disciplinary matters, issued by the pope in his own name.  They are published as either universal or particular law of the Church.  (Examples: the Constitution on the Liturgy, Sacrosanctum Concilium; Constitution of the Catechism of the Catholic Church)

Apostolic exhortation (apostolica exhortatio): a papal reflection on a particular topic that does not contain dogmatic definitions or policy directives, addressed to bishops, clergy and all the faithful of the entire Catholic Church.  Apostolic exhortations are not legislative documents.  (Example: Familiaris Consortio, on the Role of the Christian Family in the Modern World).

 Apostolic Letter (apostolica epistola): a formal papal teaching document, not used for dogmatic definitions of doctrine, but to give counsel to the Church on points of doctrine that require deeper explanation in the light of particular circumstances or situations in various parts of the world.

 Declaration (declamatio): may be a simple statement of the law, which must be interpreted according to the existing law; or an authoritative declaration that is retroactive and does not require further promulgation; or an extensive declaration, which modifies the law, is not retroactive and must be promulgated according to the law.

 Decree (decretum): a statement involving Church law, precepts or judicial decisions on a specific matter.  It is an ordinance given by one having the power of jurisdiction (such as a bishop within his particular diocese, the head of an office of the Roman Curia, or the pope), acting administratively to promote compliance with the law.  A decree announces that a given document or legislative text is in effect.

 Encyclical (encyclical epistola - literally "circular letter"): a formal apostolic letter issued by the pope usually addressed to the bishops, clergy and faithful of the entire Catholic Church.  Example, Humanae vitea, concerning the Church's teaching on birth control issued in 1968 by Pope Paul VI.

 Instruction (instructio): explains or amplifies a document that has legislative force, such as apostolic constitutions, and states how its precepts are to be applied.  (e.g., Liturgiam authenticam, on liturgical translation, or Instruction on the correct implementation of the Constitution of the Lirturgy, Sacrosanctum Concilium.)

 Institutio: instituted arrangement of regular method, rules (as in Institutio Generalis Missalis Romani).

 Motu proprio (literally, by one's own initiative): a legislative document or decree issued by the pope on his own initiative, not in response to a request. (Examples: Apostolos Suos; Misericordia Dei.)

Promulgation (promulgatio): the process whereby the lawmaker communicates the law to those to whom the laws has been given.  (The official effective date on which a document is promulgated may or may not coincide with the date on which a document is actually published.)

 Recognito: confirms the review of documents that are submitted by a conference of bishop to the relevant office (dicastery) of the Holy See.  Recognitio is required before provisions of documents that modify universal law may come into effect.  Recognito thus signals acceptance of a document that may have legislative force.  ( Recognitio is required for all documents that modify universal liturgical norms, for example).

  reprinted from Adoremus Bulletin, September 2002, published by the Society for the Renewal of the Sacred Liturgy.