/summa/FS/FSVI/FS_Q97:
We must now consider change in laws: under which head there are four points of inquiry:
(1) Whether human law is changeable?
(2) Whether it should be always changed, whenever anything better occurs?
(3) Whether it is abolished by custom, and whether custom obtains the force of law?
(4) Whether the application of human law should be changed by dispensation of those in authority?