Positive commandment · Mitzvat Aseh #246 of 613
To render judgment [in questions] regarding claims made by one person against another
לדון בדין טוען וכופר
The verse · Shemot 22:8
עַל־כׇּל־דְּבַר־פֶּשַׁע עַל־שׁוֹר עַל־חֲמוֹר עַל־שֶׂה עַל־שַׂלְמָה עַל־כׇּל־אֲבֵדָה אֲשֶׁר יֹאמַר כִּי־הוּא זֶה עַד הָאֱלֹהִים יָבֹא דְּבַר־שְׁנֵיהֶם אֲשֶׁר יַרְשִׁיעֻן אֱלֹהִים יְשַׁלֵּם שְׁנַיִם לְרֵעֵהוּ
“For all manner of trespass, whether it be for ox, for ass, for sheep, for a garment, or for any manner of lost thing, of which one can say, This is it, the cause of both parties shall come before the judges; and whom the judges shall condemn, he shall pay double to his neighbour.”
The Rambam’s words
To render judgment [in questions] regarding claims made by one person against another, as [Exodus 22:8] states: "For every matter of trespass, concerning an ox, concerning a donkey, or concerning a sheep...."
לדון בדין טוען וכופר, שנאמר: "על כל דבר פשע" (שמות כב,ח).
Why · Sefer HaChinuch #58
The commandment on the court to judge the case of a plaintiff and a defendant
“The root of the laws is well-known.”
Who & when
“And this commandment that we are obligated to judge is practiced by males, but not by females, as they do not judge.”
Where in the Mishneh Torah
Hilchot Plaintiff and Defendant הלכות טוען ונטען