Father Hesse:
"... Paul IV was also the one who issued the papal bull cuм Ex Apostolatus Officio that determined that a former heretic could not become pope. What I really should, for practical reasons, not passing any judgement on anyone here, but for practical purposes, I should say the '1958 sedevacantists'--those who believe that John XXIII was not pope because before he was elected he was a heretic. ... The next pope who wrote about the laws of how to elect a pope didn't even mention cuм Ex Apostolatus Officio. And the papal practice was even worse. While Paul IV in cuм Ex Apostolatus Officio says a former heretic cannot become pope, privately he made sure that every cardinal understood that one who was formerly suspect of heresy could not become pope. Now Leo XIII beautifully contradicted that when he made the former heretic, John Henry Newman, Cardinal John Henry Newman. So Leo XIII theoretically made a former heretic, John Henry Newman, Anglican minister who converted Catholic, became a Catholic priest, John Henry Cardinal Newman, therefore he was eligible to the papacy. Out goes cuм Ex Apostolatus Officio, written by a paranoid pope anyway."