The papal conclave of 2005 was convened to elect a pope, the leader of the Catholic Church, to succeed Pope John Paul II following his death on . According to the apostolic constitution "Universi Dominici gregis", which governed the vacancy of the Holy See, only cardinals who had not passed their 80th birthday on the day on which the Holy See fell vacant (i.e. cardinals who were born on or after ) were eligible to participate in the conclave. Although not a formal requirement, the cardinal electors invariably elect the pope from among their number. The election is carried out by secret ballot ().