A Look Back: A Canonical and Theological Study of the SSPX Part 7 - Theological Study 2
II. Solution of the Problem posed by the Pope's "No"
A. The Pope's "No"
B. A Word on Epikeia
...the coming into play of epikeia is subordinate to the existence of a right. In fact, in certain cases, the law loses its power to bind -- as where its application would be contrary to the common good or to natural law -- and in such a case it is not in the power of the legislator to bind or to oblige.(19)...There is a place for epikeia because the will of the legislator either is not able or is not bound to impose the application of the law to the case in question.(20)
that in such a case the authority of the superior cannot have any effect; indeed, even if he were to will that the subject, after having had recourse to him, should observe the law, the latter would not be able to obey him because he must obey God rather than man and hence in such a case it is out of place ("impertinens") to ask for permission.(29)
C. Refutation of More False Objections
Moralists have sought to fix the criteria to be laid down for the application of epikeia. In substance, these criteria come down to the three following cases: a) when in a particular situation, the prescriptions of the positive law are in opposition to a superior law which binds one to regard higher interests [i.e., epikeia in the proper sense]; b) when, for reason of exceptional circumstances, submission to the positive law would be too burdensome, without there resulting a good proportionate to the sacrifice being demanded; c) when, without becoming evil as in the first case and without imposing an unjustified heroism as in the second case, the observance of the positive law runs into special and unforeseen difficulties which render it, as it turns out, harder than it should have been according to the intention of the legislator.(35)
It is said that the purpose of the law ceases "contraire" [through contrary custom --Ed.] when its observation is harmful. If the purpose of the law in a particular case ceases "contraire," the law ceases [to oblige]. The reason is that if the purpose of the law ceases "contraire," then one has the right to use epikeia.
In cases that happen rarely, and in which it is necessary to depart from the ordinary law...a virtue of judgment is needed based upon these higher principles, a virtue which is called gnome and which implies a particular perspicacity of judgment (ST, II-II, Q.51, A.4).
The spiritual man receives from the habit of charity the inclination to judge rightly of everything according to divine laws, arriving at his judgment by means of the gift of wisdom, even as the just man arrives at his judgment in accordance with the rules of law through the virtue of prudence (ST, II-II, Q.60, AA.1,2).