This principle of Catholic canon law is rooted in the aequitas (“equity”) of Roman law, in biblical thinking, and in Aristotle's theory of epikeia (Epiky). The aim of the aequitas canonica (unlike that of epikeia) is to achieve a harmony between already codified law and the legal judgment required in a specific situation. The effect is a moderation of existing law; on occasion, however, the law may also be tightened (oikonomia).
E. Wohlhaupter, Aequitas canonica, 1931
G. Wingren, art.
“Billigkeit” TRE VI, 1980, 642–645
A. Hollerbach, art. “…