Responsa for Bava Batra 14:3
ההוא שטרא דיתמי דנפיק עליה תברא אמר רב חמא אגבויי לא מגבינן ליה ומיקרע לא קרעינן ליה אגבויי לא מגבינן ליה דנפק תברא עליה מיקרע לא קרעינן ליה דכי גדלי יתמי דילמא מייתו ראיה ומרעי ליה
against the other, nor the right of 'ladders'<span class="x" onmousemove="('comment',' The right to rest a ladder in the other's courtyard in order to climb to his own room, or even to place the ladder in his own courtyard and let it rest against the other's room (v. Tosaf.). ');"><sup>5</sup></span> against the other, nor the right of a watercourse<span class="x" onmousemove="('comment',' The right to carry water from the river to his own field through the other's; all this notwithstanding the fact that the father was accustomed to do these things. ');"><sup>6</sup></span>
Teshuvot Maharam
A. Matters of taxation depend on local custom. It is needless to ask me the custom of our community, for you may have a different custom. Anyone who settles in a new place is bound by the custom prevailing there. But since the community has completely settled its obligations to the burghers, by consenting to pay the tax to A, before Leah settled in T, the representatives of the community must prove through witnesses who are not residents of T, that according to their custom Leah was obliged to pay the amount the community demanded, before they could deprive her of any of her property. If Leah, however, rented a house in T before the tax was levied, she is bound to pay her share of the tax, despite the fact that the community may not be able to prove any prevailing custom to that effect.
SOURCES: Pr. 995. Cf. Menahem of Merseburg, Nimmukim (8).