Catholicism’s commemoration of the 60th anniversary of the Second Vatican Council this week has prompted a fresh reflection on the changes that came out of the historic event and the years immediately after, including the proposal of a mandatory papal retirement age.

The council was formally opened by Pope Saint John XXIII on Oct. 11, 1962, and it was closed by Pope Saint Paul VI on Dec. 8, 1965.

In the 1965 Vatican II decree Christus Dominus, “Concerning the Pastoral Office of Bishops in the Church,” it was stated that, “Since the pastoral office of bishops is so important and weighty, diocesan bishops and others regarded in law as their equals, who have become less capable of fulfilling their duties properly because of the increasing burden of age or some other serious reason, are earnestly requested to offer their resignation from office either at their own initiative or upon the invitation of the competent authority.”

“If the competent authority should accept the resignation, it will make provision both for the suitable support of those who have resigned and for special rights to be accorded them,” the decree said.

The rule of a mandatory retirement age for bishops was first imposed in 1966, a year later and a year after the council formally, when Paul VI issued his apostolic letter Ecclesiae Sanctae, or “[Governing] of the Holy Church,” which established a retirement age of 75 for Catholic bishops around the world.

Although the decree, easily among the most consequential papal edicts of the past century, was issued after the council was over, it is still considered part of the “reforming spirit” of Vatican II, and of Paul VI’s own papal tenure.

Four years later, in 1970, Paul VI issued a similar decree titled, Ingravescentem Aetatem, or “Advancing Age,” applying the mandatory retirement age of 75 to cardinals and establishing the rule that only cardinals who have not reached the age of 80 can participate in a conclave.

These rules still stand to this day, however, Pope Francis in 2014 made some of his own adjustments, stipulating in a 2014 papal rescript that rather than “inviting” prelates to tender their resignations, which was the language used by Paul VI, cardinal heads of all Roman Curia offices “are required” to present their resignation on reaching the age of 75.

He also reinforced the encouragement for diocesan bishops who feel incapable with carrying out the demands of the job to ask for early retirement, and he imposed the norm that “the competent authority,” when it considers it necessary, can ask a bishop to retire.

Pope Francis issued some modifications to the rescript rules in a 2018 motu proprio, Imparare a congedarsi, meaning “Learning to take your leave,” in which he clarified that non-Cardinal dicastery Heads in the Roman Curia, superiors of the Roman Curia and bishops holding other offices of the Holy See “do not ipso facto cede their office,” nor do papal representatives abroad, but they must await the pope’s decision.

Despite these rules, in recent decades many bishops and cardinals have tended to stay in office for several years beyond 75, as have bishops and archbishops of major dioceses and archdioceses, however, the rules generally still apply, and with Pope Francis’s pledge to be stricter about the 5-year term limits for curial department heads, the mandatory retirement age could be more closely observed.

Notably, there is no mandatory retirement age for popes, as they hold the position for life once they are elected.

In the wake of Vatican II and Paul VI’s imposition of a mandatory retirement age for bishops and cardinals, there was some discussion about whether a similar decree might be issued limiting a pope’s time in office.

With Tuesday’s 60th anniversary of the opening of the Second Vatican Council, which comes just nine years after Pope Benedict XVI’s own resignation from the papacy, for reasons of age and failing strength, there is fresh buzz about the possibility of a mandatory papal retirement, and whether it is a reasonable proposal.

Asked about the possibility of setting a papal retirement age of 80, when cardinals lose their conclave voting rights, during a 2015 interview with Valentina Alazraki of the Mexican television station Televisa, Pope Francis voiced skepticism.

“One could imagine it, but the idea of setting an age limit does not appeal to me, because I believe that the papacy has an element of being the final authority. It is a special grace,” he said, noting that some theologians go so far as to hold the papacy as “a sacrament.”

Francis said he does not share that specific view, but insisted that when it comes to the papacy, “there’s something special. So, saying ‘OK, this fellow is 80 years old,’ creates the sensation of the ending of a pontificate which would not be good.”

Yet while he did not support setting a papal age limit, Francis did say he was in favor of Benedict’s decision to retire after coming to the spontaneous conclusion that he could no longer fulfill the obligations of his office.

Even in John Paul II’s day, some thought the aging pontiff ought to resign, including a 25-year-old art student named Luca Mastroserio who was quoted by the Wall Street Journal in 2000 during John Paul II’s visit to the Holy Land as saying, “like all people, when they’re old, they retire.”

John Paul II never did retire but died in office in 2005 at the age of 84 due to complications from Parkinson’s Disease.

When Benedict XVI stepped down in 2013, he cited not only age, but also energy and capacity, stating that he no longer had the strength to carry out the demands of his office, which has been an increased concern for popes, as people generally are living longer thanks to modern medical advancements.

Given all this, some have argued that a mandatory papal retirement age is something worth discussing since a longer life doesn’t necessarily mean a stable mental and physical capacity.

In the wake of Benedict XVI’s retirement, some observers have questioned whether his decision was motivated, in addition to his own physical limitations, by having witnessed John Paul II’s decline and consequent inability to effectively govern, with close aides making many of the major decisions toward the end.

All those could be arguments in favor of a mandatory papal retirement age, however, the arguments against it would be more on a practical level, in that no one can mandate popes to do anything.

If Pope Francis were to issue legislation tomorrow imposing a papal retirement age of 80, there’s nothing that would stop his successor from repealing that edict five minutes after taking office, as the pope is both the supreme civil and judicial authority of the Holy See and is legally beholden to no one other than himself.

Pope Francis himself has said he is willing to resign if he ever believes the time is right, but that until now he hasn’t considered it, and he has shown no indication that he is slowing down, despite ongoing knee pains and problems with sciatica.

Whether this proposal is one worthy of serious discussion is for theologians and, ultimately, the pope to decide, but it doesn’t seem that Pope Francis will be the one to do it.

Follow Elise Ann Allen on Twitter: @eliseannallen