Halakhah к Бава меци'а́ 2:12

The Gemara (Bava Metzia 24b) relates that Mar Shmuel ruled that one “must” return a lost object if one positively knows the owner’s identity. Mar Shmuel based his ruling on lifnim mishurat hadin, whereas the strict letter of Torah law often entitles the finder to keep a lost item.⁶The Gemara devotes the second chapter of Bava Metzia to discussing when one may keep a lost item, when one should leave the item where it is, and when one must attempt to return it to its owner. The Rishonim debate the nature of Mar Shmuel’s insistence that one “must” act lifnim mishurat hadin.⁷The possibility of coercing to act lifnim mishurat hadin raises the question of how precisely lifnim mishurat hadin differs from the letter of the law if a Jew must comply with both. Rav Aharon Lichtenstein (Leaves of Faith 2:46-48) grapples with this question at length and argues, “Lifnim mishurat hadin is the sphere of contextual morality…. Guided by his polestar(s), the contextualist employs his moral sense to evaluate and intuit the best way of eliciting maximal good from the existential predicament confronting him.” The Mordechai (Bava Metzia 257) cites the Ra’avan and Ra’avyah, who assert that a beit din may coerce a litigant to act lifnim mishurat hadin provided that he can afford to do so. However, the Beit Yosef (Choshen Mishpat 12) notes that the Rosh (Bava Metzia 2:7) writes, “We do not coerce him to act this way, as we cannot coerce to act lifnim mishurat hadin.”