One does not obligate a person except in their presence
A person is not judged to their detriment or obligated with a liability unless they are present or have the right to present their position on the matter. However, one may grant a benefit to a person even in their absence.
("In the matter of joining courtyards, one may establish an eruv on someone's behalf with or without their knowledge, because one may grant a benefit to a person even in their absence, but one does not obligate them except in their presence" - Eruvin 7b)
Translation
Expression (Hebrew)
אֵין חָבִין לָאָדָם שֶׁלֹּא בְּפָנָיו
Definition (Hebrew)
אֵין דָּנִים אָדָם לְחוֹבָה אוֹ יוֹצְרִים חוֹב לְרָעָתוֹ מִבְּלִי שֶׁהוּא נוֹכֵחַ וְשֶׁיֵּשׁ לוֹ אֶת זְכוּת הַטִּעוּן לְהַבָּעַת עֶמְדָּתוֹ בְּנוֹשֵׂא. וְאוּלָם 'זַכִּין לָאָדָם שֶׁלֹּא בְּפָנָיו'.
("בְּעֵרוּבֵי חֲצֵרוֹת, מְעָרְבִין לְדַעְתּוֹ וְשֶׁלֹּא לְדַעְתּוֹ, לְפִי שֶׁזַּכְיָן לוֹ לְאָדָם שֶׁלֹּא בְּפָנָיו, וְאֵין חָבִין לוֹ אֶלָּא בְּפָנָיו"- עֵרוּבִין ז יָא)