VATICAN CITY: Pope John Paul's latest illness has raised the question of what the Church would do if he were permanently incapacitated - and reopened debate over whether Popes should retire instead of reigning for life.

Like that of any large international organization, the Vatican's bureaucracy hums away even between the election of leaders or when a leader is sick. But unlike the leaders of those institutions, the head of the world's Roman Catholics is a monarch who traditionally rules for life. No Pope has abdicated since before Columbus reached America.

Modern medicine has created a quandary for an institution that changes only reluctantly. In the past, nature took its course, Popes died earlier, and the problem rarely arose.

"Without the advances of modern medicine, this Pope would not have survived all his various illnesses and brushes with death," said Alberto Melloni, a Church historian.

Church law says a Pope can resign of his own free will, but there are no clear regulations in Church law for the very real possibility that a Pope may be alive but incapacitated for a long time or even the rest of his life.

"The ability of modern medicine to keep the body alive while the mind is deteriorating will eventually present the Church with a constitutional crisis," wrote Father Thomas Reese, author and editor of the weekly US Jesuit journal America.

The late James Provost, a specialist on Church law, wrote that the lack of clear guidelines on what to do if the Pope became severely or permanently disabled was "a rather serious vacuum in the Church's constitutional law".

In the future, perhaps as soon as the conclave to elect the next Pope, Church historians expect that the subject of papal retirement will break out of the taboo. "I'm convinced the subject of the duration of the papacy is something that will come up in the next conclave," Melloni said.

"It's a question of time. The change will be slow and the perception of retirement will change. When the bishop of Milan resigns, no-one says he is a traitor or a weakling." Bishops normally retire at 75 and cardinals over 80 cannot enter conclaves to elect Popes. -Reuters