"Levis" has a juridical pedigree. In Roman law its most famous use is with the word "culpa" in the Lex Aquilia. Every student of Roman law learns that "culpa levissima" still obligates a person who has committed a delict.   The jurists also used the adjective to describe a mild or minor crimes and punishments. To the jurists it never meant no fault, crime, or punishment; it meant a lesser fault, crime, or punishment.

Infertur ergo quod in hac actione legis Aquiliae venit levissima culpa de iure canonico sicut de iure ciuili, ut in l. Aquilia, ff. ad leg. Aquil. et dicitur levissima culpa quod diligentissimus homo sciuisset praecavere. 

Panormitanus, Commentaria to X 5.36.9 (1582) vol. 7, fol. 235r