By Peter Gould
Religious affairs analyst
The Vatican's new policy on homosexuality and the priesthood seems certain to cause further controversy within the Catholic Church.
Some fear the policy will discourage new applicants for the priesthood
Due to be officially released on Tuesday, the 1,300-word document was leaked a week ago, when an Italian news agency posted details on its website.
Having had time to digest the new ruling, some Catholics say they are confused about what it really means.
The issue has provoked a fierce debate in the United States, where revelations about paedophile priests led to a scandal that reverberated around the Catholic world.
Faced with the question of whether to ordain gay men, the Vatican seems to have stopped short of an outright ban.
It says anyone who is actively gay, or has "deep-seated" homosexual tendencies, or who supports the "gay culture", should not in future be ordained.
But it says that such tendencies might be a manifestation of a "transitory problem". This has to be overcome at least three years before the man is ordained as a deacon - the step before priesthood.
John Allen, Vatican correspondent of the National Catholic Reporter, says the document does not define "deep-seated homosexual tendencies", leaving it unclear how exactly they differ from "transitory" impulses.
"The instruction never uses the word 'orientation' or 'condition' with respect to homosexuality," he says. "Instead it refers to 'tendencies', a seemingly deliberate choice, suggesting that homosexuality is an impulse or inclination which can be reversed."
The Vatican's choice of language is puzzling some of the Church's own experts.
Father Thomas Reese, a Jesuit scholar based in California, also questions the use of the word "tendencies".
"Is 'tendencies' the equivalent of 'orientation' or does it mean something else?" he asks. "The document never uses the 'O' word, which has left many people scratching their heads."
Father Reese says it can be inferred from the Church's previous teaching that "deep-seated homosexual tendencies" are not chosen but are some kind of innate instinct, or an incurable pathological constitution.
"Is this the Vatican definition of homosexual orientation?" he asks.
"Some canon lawyers and theologians will undoubtedly argue that even under this new instruction a bishop could still ordain to the priesthood a mature, celibate homosexual."
John Allen: The Vatican's definitions are left unclear
With the decision on individual cases being left to bishops and religious superiors, the Vatican is urging candidates for the priesthood to be honest about their sexuality.
The number of homosexual priests already in the Catholic Church is a matter for speculation; there are no definitive figures.
"The US bishops have discouraged researchers from asking questions about sexual orientation because they know that the results would make front-page news across the country," says Father Reese.
"They don't know because they don't want anyone else to know. As a result, the Vatican is making decisions about the appropriateness of ordaining homosexuals in total ignorance of how many current priests are homosexuals, how well they observe celibacy, and how well they do ministry."
There has been talk of a "homosexual subculture" in the priesthood, and a "Lavender Mafia" that operates within the American church. This hidden network, it is claimed, promotes a gay agenda and seeks to cover up scandals.
Concern has been expressed that this subculture may deter young men from training for the priesthood, at a time when there is a serious shortage of new recruits for the ministry in the United States and Western Europe.
Michael Rose, the author of a study of American seminary life called "Goodbye, Good Men", believes the teachings of the Church are being undermined.
"One aspect of this gay subculture of both priests and seminarians is that too many men who want to be chaste, whether gay or straight, are propositioned, harassed or even molested," he wrote in a recent article for the Dallas Morning News.
"This is not simply about homosexuality or homosexual acts. It is about an agenda and subculture that systematically undermine celibacy."
Some Catholics believe homosexual orientation should be an automatic disqualification for the priesthood. But for others, the key issue is whether the man - no matter what his sexual orientation - can remain celibate and become a good priest.
While the Vatican's new policy document was prompted by the sex-abuse scandal within the United States, it is intended for the worldwide Church.
"Sad to say, reports from more and more countries are now showing that sexual abuse is not a uniquely American problem," says Father Reese.
"Although there is still a great deal of homophobia in the United States, it pales by comparison with Africa and Latin America, where many both inside and outside the church would deny there are any homosexuals.
"Bishops in Africa and Latin America would certainly not welcome a document that indicated any openness to homosexuals in the clergy.
"In Africa, such a document would open the church to attacks from Muslim clerics and in Latin America it would open the church to attacks from fundamentalists. Only in the United States is this issue even being discussed."