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James T. KeaneMay 15, 2024
Cardinal Mauro Gambetti, archpriest of St. Peter's Basilica, is pictured near a bull during the blessing of farm animals and Italian military horses outside St. Peter's Square at the Vatican Jan. 17, 2023. The traditional event returned after a two-year hiatus on account of the COVID-19 pandemic. (CNS photo/Paul Haring)

Last Thursday, May 9, Pope Francis promulgated “Spes Non Confundit,” a Bull of Indiction for the Jubilee Year of 2025 that he will open in St. Peter’s Basilica on Dec. 24, 2024. In the official ceremony promulgating the bull, whose title translates loosely as “Hope does not disappoint,” Francis gave copies to bishops representing the four major basilicas of Rome as part of a symbolic dissemination of the bull at a ceremony in front of the Holy Door of St. Peter’s Basilica.

What is a Jubilee Year? Instituted in 1300 and normally held every 25 years, a Jubilee Year is, in the Vatican’s words, “a year of forgiveness of sins and also the punishment due to sin, it is a year of reconciliation between adversaries, of conversion and receiving the Sacrament of Reconciliation, and consequently of solidarity, hope, justice, commitment to serve God with joy and in peace with our brothers and sisters.”

But let’s get to the real question: What on earth is a papal bull?

No, it won’t gore you for wearing red or trample you on the streets of Pamplona. But for many centuries, it has been the desired method of communication by popes. Named after the lead seals that were used on official papal documents (“bulla” in Latin), bulls can include within them all manner of decrees and appointments—even excommunications, canonizations and the promulgation of apostolic constitutions. The infallible declaration of the dogma of the Immaculate Conception in 1854, “Ineffabilis Deus,” came in a papal bull. The infallible declaration of the dogma of the Assumption of Mary in 1950, “Munificentissimus Deus,” was one, too.

For the Society of Jesus—which historically has played the role of Billy Martin opposite the papacy’s George Steinbrenner—papal bulls have often marked the rise and fall of the order’s fortunes. The Jesuit order was officially approved by Pope Paul III in 1540 with a papal bull, “Regimini Militantis Ecclesiae.” More than two centuries later, Pope Clement XIV used the bull “Dominus ac Redemptor” to dissolve the Jesuits (for the most part) in 1773. But in 1814, Pope Pius VII issued yet another bull, “Sollicitudo Omnium Ecclesiarum,” that restored the Society of Jesus. There’s even a change.org petition out there today that pleads with Pope Francis to reissue “Dominus ac Redemptor.” (No, I won't provide a link.)

Papal bulls tend to be used for announcing Jubilee Years these days, though oftentimes the term is used to describe almost anything that comes out of the Vatican. But where do papal bulls rank in the hierarchy of Vatican documents? How authoritative are they in comparison?

A hierarchy of authority

There are Catholics who never tire of reminding everyone that the church is very careful not to say anything too authoritatively and that papal infallibility has only been invoked twice in the history of the church (true). There are Catholics who claim The Catechism of the Catholic Church is infallible (false). And there are Catholics who treat every utterance of the pope as if it instantly becomes part of the deposit of faith (very, very false). In between are the rest of us, maybe more or less sure what the church teaches but never entirely clear on the levels of authority different documents and declarations have.

Because of the sheer diversity of options available to the church hierarchy around the world for communicating church teaching and the way these have sometimes changed in importance over time, history can become clouded. For example, everyone knows that Galileo was excommunicated—except he wasn’t. Everyone also knows that Popes John Paul II and Benedict XVI condemned liberation theology—except they didn’t. Another example: When Pope John Paul II visited the United States in 1987, William F. Buckley, then the editor of National Review, claimed that 25 years before, the editors of America had “tried to get me excommunicated!” It was, of course, a lot of non-papal bull: America had criticized Mr. Buckley’s flippant response to John XXIII’s 1961 encyclical “Mater et Magistra,” writing that “lines spoken to the Pope just shouldn’t sound like lines pitched at the editors of the New York Post.” Hardly an excommunication—though a pretty good line.

While the Vatican offers no hard and fast set of rules for authoritative statements (in part because different public statements often include within them declarations that themselves have varying levels of authority), what follows is a quick primer on the topic.

Infallible declarations

A fairly new arrival on the papal scene, papal infallibility was defined at the First Vatican Council and declared in 1871. It marked a significant expansion in the teaching authority of the pope—more than one historian has called Vatican I “the council of the papacy”—because the infallibility assumed to be a characteristic of the church as a whole was now officially recognized as having a Petrine dimension. But the dogma in no way means that a pope cannot err. (Remember, we once had a pope who banned trains.) Rather, an infallible declaration requires the use of specific language and circumstances: The pope must explicitly intend to speak “ex cathedra” (Latin for “from the chair,” meaning the chair of Peter) on “matters of faith and morals” to the entire church.

As mentioned above, infallibility has been invoked only twice: at the declarations of the dogma of the Immaculate Conception in 1854 and of the Assumption of Mary in 1950. Some Catholics claim that the church has infallibly declared that women cannot be priests because Pope John Paul II declared that “this judgment is to be definitively held by all the Church’s faithful” in “Ordinatio Sacerdotalis” in 1994, but it is noteworthy that he was careful not to use the aforementioned specific language invoking infallibility in that document.

Apostolic constitutions

Whether issued in the context of an ecumenical council or not, apostolic constitutions are the heavyweights of Vatican documents. Often intended to address (and sometimes to signify the importance of) serious matters of faith and morals, such constitutions can define dogmas, create new church structures, change canon law or call for sweeping changes in Catholic practice. Four of the documents of Vatican II—“Sacrosanctum Concilium,” “Gaudium et Spes,” “Dei Verbum” and “Lumen Gentium”—were apostolic constitutions.

That last extremely influential constitution—known in English as “The Dogmatic Constitution on the Church”—offered a take on infallibility that feels simpatico with the historian’s notion that Vatican II was “the council of the bishops”:

Although the individual bishops do not enjoy the prerogative of infallibility, they nevertheless proclaim Christ’s doctrine infallibly whenever, even though dispersed through the world, but still maintaining the bond of communion among themselves and with the successor of Peter, and authentically teaching matters of faith and morals, they are in agreement on one position as definitively to be held. This is even more clearly verified when, gathered together in an ecumenical council, they are teachers and judges of faith and morals for the universal Church, whose definitions must be adhered to with the submission of faith (No. 25).

Outside the context of an ecumenical council, the three most recent popes have been big fans of apostolic constitutions as regular tools for governance, but they typically used them for less weighty matters than the famous examples above. This has included everything from announcing the creation of new dioceses to reforming the church’s bureaucracy to altering the way papal elections are held. However, every now and then an apostolic constitution appears that causes more of a stir, like John Paul II’s 1990 “Ex Corde Ecclesiae” on the mission and identity of Catholic colleges and universities.


Letters addressed to the bishops of the worldwide church (but almost always intended for universal consumption), encyclicals usually engage on a social issue of concern to the church at that time. They typically don’t have the doctrinal weight of an apostolic constitution, but they are its flashier cousins. In the past two centuries, these “circular letters” have become prominent vehicles by which popes not only offer guidance to Catholics but also advance Catholic teaching in areas pertinent to contemporary life. For example, the great “social encyclicals” of the church, which often served to identify the causes of (and offer remedies for) injustice in the modern world, have all been published since 1891, beginning with Pope Leo XIII’s clarion call for worker justice in “Rerum Novarum” and running through to Pope Francis’ “Fratelli Tutti” amid the Covid-19 pandemic in 2020.

The church’s concerns about Modernism and dissent in the 19th and early 20th centuries prompted some of its most polemical encyclicals, including Gregory XVI’s 1832 “Mirari Vos” and 1834 “Singulari Nos” (which condemned freedom of the press and the separation of church and state), Pope Pius IX’s 1864 “Quanta Cura” (which was accompanied by the original “Syllabus of Errors”) and Pope Pius X’s 1907 “Pascendi Dominici Gregis.”

Perhaps the most well-known encyclical of the last two centuries is Pope Paul VI’s 1968 “Humanae Vitae,” which upheld the church’s prohibition on artificial birth control. Hailed as prophetic by its defenders, the encyclical was also met with consternation from a number of bishops of the world. More significantly, it encountered widespread resistance from the laity—a 2023 study estimated that more than 90 percent of U.S. Catholics have used artificial birth control at some point. In this sense, the encyclical raised a question that has long lurked beneath church declarations: If the sense of the faithful (“sensus fidelium”) runs counter to the teaching of the Vatican, can that teaching be considered to be “received”? And if it is not received, is it a valid teaching at all?

A step down from encyclicals tends to drop one more into the weeds when it comes to the level of authority the remaining kinds of Vatican documents have—and how they relate to one another. But at the top of the heap in this grouping are apostolic exhortations.

Apostolic exhortations

An apostolic exhortation does not typically attempt to define doctrine but instead serves as an encouragement of a specific community toward a certain goal or practice. Probably the most influential in the post-Vatican II era was Paul VI’s 1975 exhortation on evangelization, “Evangelii Nuntiandi.” Pope Francis has also used apostolic exhortations as vehicles to advance some of the central themes of his papacy, including 2013’s “Evangelii Gaudium,” 2016’s “Amoris Laetitia,” 2020’s post-synodal exhortation “Querida Amazonia” and the follow-up to “Laudato Si’,” 2023’s “Laudate Deum.”

Apostolic letters

Apostolic letters are normally used to address important issues of governance and administration that don’t rise to the level of needing an apostolic constitution. Many “motu proprio” decrees (defined below) are promulgated in apostolic letters.


A declaration is typically used by popes and Vatican dicasteries to clarify or modify existing church law. This can sometimes entail the study of particular church practices, such as the 2023 declaration “Fiducia Supplicans,” in which the Dicastery for the Doctrine of the Faith laid out particular circumstances in which pastoral blessings could be offered to people in irregular marital situations.

Note that while declarations are usually released by a Vatican dicastery, they are still signed by the pope.

‘Motu proprio’ decrees and letters

A decree (or apostolic letter) issued “motu proprio” is one issued by the pope on his own authority and initiative. Usually more concerned with church law and practice than with doctrine, they are often used by popes to tweak church law or extend privileges to a particular person or group. The two most famous “motu proprio” examples in recent years were Pope Benedict XVI’s 2007 “Summorum Pontificum,” loosening restrictions on the celebration of the Traditional Latin Mass, and Pope Francis’ 2021 “Traditionis Custodes,” which placed new restrictions on such celebrations and affirmed the current post-1970 liturgy as normative for the church.

The rest

What lies beneath this second grouping of authoritative documents? Allocutions. Decretal letters. Responses to dubia. Notifications. Monita. Notes. Apostolic briefs. What lies beneath that? Papal audiences, both formal and informal. Books about Jesus. Homilies. Interviews. Off-the-cuff remarks on airplanes.

Except, that is, when the pope offers praise and encouragement to journalists. Then he is most certainly speaking ex cathedra.

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