From: Rabbi Moshe Sofer
To: Rabbi Elyakim Getz Konigsberg
The Chasam Sofer rejects Rabbi Getz's specific proofs against the Noda BiYehudah but agrees with his conclusion. He argues that the Rosh's principle—that one cannot appoint an agent to cause detriment to others—applies only to strangers with whom the sender has no legal relationship, not to a wife whom the Torah explicitly authorizes a husband to divorce through an agent. Since the Torah's section on divorce addresses cases against the wife's will and simultaneously derives the institution of agency from the word "v'shilchah," it would be untenable to limit agency only to consensual divorces.
Source: Shu"t Chasam Sofer EH II §6