During the vacancy of the Apostolic See, laws issued by the Roman Pontiffs can in no way be corrected or modified.
All heads of departments (including the Secretary of State and Prefects of Congregations) cease to exercise their office and the day-to-day running of the church is done by the College of Cardinals, called together by the Dean.
The routine business of departments is looked after by their Secretaries. Important decisions are taken by the College of Cardinals, but they have no power to take decisions that would normally be left to the Pope himself. One of the most important priorities is preparation for the election of the new Pope.