ROME (Reuters) - Cardinal George Pell, a leading Roman Catholic conservative, said the Vatican needs clear rules to govern the status of future popes who resign rather than rule for life and that such a move would help Church unity. Pell is one of the highest-ranking Church figures to speak publicly on the need for rules since 2013, when former Pope Benedict, 93, became the first pontiff in 700 years to abdicate. Church law says a pope can resign, as long as he does so willingly and not under pressure, but it lacks specific rules on his status, title, and prerogatives. “The protocols on the situation of a pope who has resigned need to be clarified, to strengthen the forces for unity,” Pell, 79, writes in his book, “Prison Journal”, which is being published this month and recounts 13 months he spent in solitary confinement. Pell, who has always maintained his innocence, was cleared of sex abuse charges in his native Australia in April and has returned to Rome. He was Vatican treasurer until 2018. Since stepping down, Benedict has occasionally allowed his views on specific subjects to be aired outside the Vatican, to the joy of some fellow conservatives who have used them as ammunition to contest his successor Pope Francis’ more open-minded and inclusive papacy. “While the retired pope could retain the title of ‘pope emeritus’, he should be re-nominated to the College of Cardinals so that he is known as ‘Cardinal X, Pope Emeritus’, he should not wear the white papal soutane (cassock) and should not teach publicly,” Pell writes. Days before Benedict abdicated on Feb. 28, 2013, he scripted his own rules, investing himself with the title pope emeritus, deciding to continue to wear white and to live in the Vatican. But his presence has caused some confusion among the faithful, with some extreme right-wing conservatives still refusing to recognise Francis as pope. “There is only one pope,” Pell said in a wide-ranging 90-minute interview with Reuters late on Monday in his Rome apartment across the street from a Vatican gate. In the book, Pell writes that “probably the measures would be best introduced by a pope who had no surviving predecessor”. That means that in the present Vatican situation, Francis would have to wait until after Benedict dies. Others have suggested that since a pope is also the bishop of Rome, a former pontiff should be called ‘bishop emeritus of Rome’. He would then be subject to the same written rules, last updated in 2004, that cover retired bishops. Those rules say any bishop emeritus “will want to avoid every attitude and relationship that could even hint at some kind of parallel authority to that of the diocesan bishop, with damaging consequences for the pastoral life and unity of the diocesan community”.