In 1967, Pope Paul VI, who charted the Catholic Church through the difficult shoals of the cultural upheavals of the 1960s, published an encyclical, or open letter to the church, entitled Sacerdotalis Caelibatus (Latin for "Of the celibate priesthood").
In it, he outlined the reasons for keeping the tradition of celibacy a part of church teaching: it was a superior way of achieving grace, it freed priests from familial obligations in order to devote themselves to God, it mirrored heaven as a place without marriage.
"In any case, the church of the West cannot weaken her faithful observance of her own tradition," Pope Paul VI wrote at the time.
Britain's most senior Roman Catholic, Cardinal Keith O'Brien, told the BBC in February that many priests struggle to cope with celibacy and should be able to marry and have a family. Just three days later he was forced to resign over allegations of a 30-year-old sex scandal with seminarians in his charge. O'Brien later admitted his conduct had "fallen below the standards" expected of a priest.
"I'd be very happy if others had the opportunity of considering whether or not they could or should be married. It's a free world and I realize many priests have found it very difficult to cope with celibacy as they lived out their priesthood, and felt the need of a companion, of a woman, to whom they could get married and raise a family," he told the British news agency.
O'Brien is not the first or the highest ranked Catholic to question the tradition of priestly celibacy. In 1993, at a weekly audience, even Pope John Paul II said celibacy did "not belong to the essence of the priesthood." Even so, he qualified this, saying there was "no doubt about its suitability and indeed its appropriateness to the demands of sacred orders."
Celibacy in the Catholic Church is a law, not a doctrine, and can be changed by the pope at any time. Despite this, Pope Benedict XVI made it clear during his tenure that the traditional practice was unlikely to change.
The Rev. Joseph Fessio, founder and editor of the U.S.-based conservative Catholic publishing house Ignatius Press, told Boston's The Good Catholic Life radio in February that while celibacy is a discipline and not a dogma, it made it no less an important part of the Catholic Church.
"People say celibacy is only a discipline, but it's not only a discipline," he told the radio program. "It's something the church in its wisdom for 2000 years has recognized as a closer, more exact, more profound following of the example Jesus set us."
In the meantime, the arguments against celibacy have been mounting.