A scholar of global Catholicism writes how Francis has opened the church to the outside world in ways no pope had done before.

The Vatican has detailed laws and rituals to ensure the transfer of power when a pope dies or resigns, but not when he is sick.

What happens when a pope is incapacitated? Is he still pope? Pope Francis' age and prolonged illness have raised questions about whether he might resign, and revived interest about how papal power is exercised.