mid-14c., "public officer appointed to administer the law" (early 13c. as a surname), also judge-man; from Old French juge, from Latin iudex "one who declares the law" (source also of Spanish juez, Italian giudice), a compound of ius "right, law" (see just (adj.)) + root of dicere "to say" (from PIE root *deik- "to show," also "pronounce solemnly").
Extended from late 14c. to persons to decide any sort of contest; from 1550s as "one qualified to pronounce opinion." In Jewish history, it refers to a war leader vested with temporary power (as in Book of Judges), from Latin iudex being used to translate Hebrew shophet.
word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).
<a href="https://www.etymonline.com/word/judicative">Etymology of judicative by etymonline</a>
Harper, D. (n.d.). Etymology of judicative. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/judicative