/summa/XP/XPII/XP_Q27:
We must now consider those whom indulgences avail: under which head there are four points of inquiry:
(1) Whether indulgences avail those who are in mortal sin?
(2) Whether they avail religious?
(3) Whether they avail a person who does not fulfill the conditions for which the indulgence is given?
(4) Whether they avail him who grants them?