May 4, 2006 — -- For decades, the Catholic Church has preached that the use of any contraception, including condoms, is a sin.
Now, Pope Benedict has asked Vatican officials to study whether condoning condoms among married couples where one of the members has HIV is consistent with the church's pro-life stance.
The debate reaches back to a centuries-old church principle -- that of the "lesser evil."
"Ever since the AIDS epidemic came on the scene, we recognize that what's at issue in this case is not simply preventing conception but actually saving life," said Jon Fuller, a Jesuit AIDS physician.
In Africa, home to 137 million Catholics and 60 percent of the world's HIV population, the church's stance against condoms has been criticized.
Some church moderates say Benedict -- known as a tough enforcer of church doctrine for his predecessor, Pope John Paul II -- is perhaps the only pope who could force this change.
Catholic conservatives say this is wishful thinking.
"According to the church, contraception is always wrong," said Joseph Capizzi, professor of theology at Catholic University. "It can never be made right. There'll be no changing that teaching as far as I can tell."
ABC's Dan Harris reported this story for "Good Morning America."