Ambrogio Lorenzetti, Justice, Palazzo Pubblico, Siena,  ca. 1340 A.D.

Summum ius summa iniuria

Cicero, De officiis 1.10.33

"In omnibus quidem, maxime tamen in iure, aequitas spectanda est" (In everything, but particularly in ius, equity must be considered) Justinian's Digest (Paulus) 50.17.90